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Evaluating kraft pulp mill fiber wastes as feedstuffs for beef cattle Bilawchuk, Maureen 1989

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EVALUATING KRAFT PULP MILL FIBER WASTES AS FEEDSTUFFS FOR BEEF CATTLE BY MAUREEN BILAWCHUK B . S c , The University of Saskatchewan, 1984 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF ANIMAL SCIENCE We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA MAY 1989 © Maureen Sandra Bilawchuk, 1989 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department The University of British Columbia Vancouver, Canada DE-6 (2/88) i i A B S T R A C T Pulp mill fiber wastes (PFW) are cellulosic byproducts from the processing of pulp. PFWs from two pulp mills, Prince George (PG) and Kamloops (K), were examined in a series of experiments to determine their suitability as ruminant feedstuffs. Initially, PFW, a high moisture substrate, was ensiled with a combination of barley (c. 16%-27%), hay (c.15%-26%), whey (c. 1.8%-3%) and urea (c. 0.8%-3%). Ensiling was shown to be an effective storage and preservation technique based on the chemical composition of the silages. In the f i r s t animal t r i a l , 20% ensiled PFW was fed to sheep. Based on intake, acid detergent fiber (ADF) content and ADF digestibility, animals were predicted to perform best on PFW silages ensiled with barley (c. 29%), whey (c. 5%) and urea (c. 1.5%). The respective dry matter digestibility (SDMD), neutral detergent fiber digestibility (SNDFD) and acid detergent fiber digestibility (SADFD) coefficients of the PFW silages ranged from 42.01-71.89%, 69.71-118.11%, and 69.45-103.41%. In the second t r i a l , on a dry matter basis 0-10% whey, barley (c. 21%) and urea (c. 1%) was ensiled with PG PFW. Hay based rations containing 20-23% ensiled PFWs were fed to sheep. No significant difference in silage dry matter or fiber digestibility was measured. However, the digestibilities tended to be highest, intake greatest and fermentation better with the 2.7% level of whey. The SDMD and SADFS coefficients for the 2.7% whey silage were respectively 82.09% and 97.74%. In the third experiment, 45% ensiled PFW was fed to four 65-87 day dairy heifers. The PG barley-whey-urea PFW silage-hay ration was acceptable and readily consumed. There was minimal sorting by heifers of PFW from the rations. i i i In the final arriirial t r i a l , 22.2% and 44.4% ensiled PFWs combined with alfalfa/grass hay, barley, canola and a vitamin-mineral premix were fed to 45 Hereford-cross steers. Over the 63 day feeding period, the average daily gain (ADG) of the test animals ranged from 1.5-1.9 kg. The ADG of the barley/hay control and 22% ensiled PG PFW fed groups were significantly higher than the ADG of 44% ensiled PFW and the K PFW fed groups. No significant differences in voluntary intake or feed conversion were detected between treatments. However, the PFWs fed were found to contain macro- and trace minerals, resin acids, chlorinated guaiacols and di-benzofurans. Beef steers which were fed rations containing 44.4% PFW did not exhibit any clinical symptoms of toxicity or illness over the 63-day period feeding period, nor were any detectable residues found in liver tissues biopsied from these animals. When water soluble and organic soluble extracts of the two PFWs were tested with in the Ames-Salmonella test, no mutagenicity was detected. The high digestibilities, intakes, average daily gains and feed conversions suggest that both the PFWs examined are cheap, high energy sources for beef cattle. Regardless, the presence of potentially mutagenic and toxic compounds identified in the PFWs prohibits i t s use as a feedstuff. Until these chemical contaminants are eliminated, or until the biological significance of such compounds is determined, the use of PFW as a cattle feed can not be recommended. iv TABLE OF CONTENTS Chapter. section Page Abstract i i List of Tables v i i List of Figures x i Acknowledgernents x i i 1.0 INTRODUCTION 1 LITERATURE REVIEW 2.0 Wood composition 4 2.1 Cellulose 4 2.2 Hemicellulose 5 2.3 Lignin 5 2.4 Extractives 6 3.0 The feeding of pulp mill fiber wastes 8 3.1 Historical perspective 8 3.2 Wood products as roughage substitutes 9 3.3 Chemical composition 10 3.4 Digestibilities of paper and pulp mill fiber wastes 12 3.5 Animal performance tria l s 13 3.6 Waste production and utilization 15 4.0 Kraft pulp process 24 4.1 The digestion process 24 4.2 The bleaching process 26 4.3 Waste management systems 27 4.3.1 The formation of pulp fiber waste 27 4.3.2 Detoxification of pulp mill wastes and effluents 30 5.0 Toxicants in the effluent and solid streams of Kraft mills 33 5.1 Volatile compounds 34 5.2 Caustic extraction products 34 5.3 Acidic compounds 35 5.3.1 Resin acids 35 5.4 Chlorinated organics 36 5.4.1 Dioxins and furans 37 5.4.1.1 Structure 37 5.4.1.2 Dioxins and the pulp industry 38 5.4.1.3 Properties 39 5.4.1.4 Dioxins and Cattle 40 5.5 Mutagenicity 41 V EXPERIMENTAL SECTION 6.0 Objectives . 47 7.0 A preliminary survey on the ensiling pulp mill fiber waste with various additives: the chemical composition of the pulp fiber waste silage and i t s effluent 49 7.1 Introduction 49 7.2 Materials and methods 50 7.3.1 Results: silages 52 7.3.2 Results: effluents 57 7.4.1 Discussion: silages — 60 7.4.2 Discussion: effluents 69 7.5 Summary 72 8.0 Measuring the apparent digestibility of pulp mill fiber waste silage using wether sheep . — 74 8.1 Introduction 74 8.2 Materials and methods 74 8.2.1 Silage preparation 74 8.2.2 Ration preparation 76 8.2.3 Sheep digestibility t r i a l 77 8.2.4 Measurement of gas production in PFW silage-hay rations .... 78 8.2.5 Statistical analyses 79 8.3 Results 79 8.4 Discussion 86 9.0 Effect of whey on preservation and digestibility of pulp mill fiber waste silage — 96 9.1 Introduction 96 9.2 Materials and methods — 96 9.2.1 Silage preparation 96 9.2.2 Ration preparation 97 9.2.3 Animal digestibility t r i a l 98 9.3 Results 99 9.4 Discussion 106 10.0 A preliminary survey of the palatability of ensiled pulp mill fiber waste as determined by dairy heifers 116 10.1 Introduction 116 10.2 Materials and methods 116 10.3 Results 117 10.4 Discussion 119 11.0 Evaluation of kraft pulp mill waste as a feedstuff for beef cattle 122 11.1 Introduction 122 11.2 Materials and methods 122 11.2.1 Experimental design and statistical analyses 122 11.2.2 Silage preparation 123 11.2.3 Experimental animals 123 11.2.4 Test rations 124 11.2.5 Digestibility coefficients of the test rations 125 11.3 Results ... 126 11.4 Discussion 134 v i 12.0 Macro and trace mineral content of pulp mill fiber waste in relation to the mineral tolerance levels for beef cattle 141 12.1 Introduction 141 12.2 Materials and methods 141 12.3 Results 141 12.4 Discussion 143 13.0 Chemical characterization and toxicological assessment of kraft pulp mill fiber waste as a feedstuff for beef cattle 145 13.1 Introduction 145 13.2 Materials and methods 145 13.2.1 Identifying and quantifying compounds 145 13.2.2 Salmonella/mammalian microsome test 147 13.2.3 Animal study 147 13.3 Results 148 13.4 Discussion 152 14.0 General Discussion 156 14.1 Economic evaluation of feeding pulp mill waste silage 156 14.2 Feasibility of pulp mill fiber wastes as ruminant feedstuff 161 14.3 Environmental considerations 163 14.4 Recommendations 165 15.0 Conclusions 168 16.0 Bibliography 171 17.0 Appendices 182 Appendix Al Volatile fatty acid analysis 182 Appendix A2 Comparison of the recovery of volatile fatty acid in samples using steam distillation with the Markham s t i l l and direct injection through Sep-pak fil t e r s onto the gas chramatograph 183 Appendix B The use of acid insoluble ash as a marker to predict dry matter digestibility of pulp mill fiber waste silage rations 186 V l l L I S T OF T A B L E S Chapter, table Page 3.1 Summary of the literature on the nutritional aspects of paper and pulp mill fiber wastes 17 5.1 The relative toxicity of identified substances in kraft pulp and paper wastes as indicated by the lethal concentration value (LC50) (adapted from Leach and Thakore, 1974b) 43 5.2 Mutagenic compounds in the spent chlorination liquor identified with three strains of Salmonella typhimurium by the SalnKDnella/mammalian-iidc3X)scmie test (taken from Kringstad and Lindstrom, 1984) 44 7.1 Proportions of ingredients on a dry matter basis of the pulp fiber waste silages 51 7.2 Chemical composition (on a dry matter basis) of the ingredients in the pulp fiber waste silage mixtures before ensiling 52 7.3 Miriimum, maximum and Day 20 temperatures (degrees C) for pulp fiber waste (PFW) ensiled mixtxires 53 7.4 Chemical composition (on a dry matter basis) of pulp fiber waste mixtures before and after ensilage, and the percentage recovery of the original nutritive components 54 7.5 Concentrations of volatile fatty acids in pulp mill fiber waste (PFW) silages 57 7.6 Chemical composition of Prince George pulp fiber waste silage effluents 58 7.7 Volatile fatty acids in the effluents produced by the Prince George pulp mill fiber waste silage treatments 58 7.8 Comparisons between the Prince George pulp mill fiber waste silages and the effluents emitted from these silages 59 8.1 Dry matter proportions (%) of the ingredients used in the pulp mill waste (PFW) treatments 75 8.2 Chemical composition of ingredients used in the pulp mill fiber (PFW) treatanents (dry matter basis) 80 8.3 Temperatures (degrees C) of the pulp mill fiber waste (PFW) treatments over a 49 day ensilage period 80 8.4 Chemical composition (on a dry matter basis) of pulp mill fiber waste mixtures after ensiling 81 8.5 Chemical composition (on a dry matter basis) of pulp mill fiber rations fed to wether sheep 81 V11X LIST OF TABLES (cont'd) 8.6 Chemical composition (on a dry matter basis) of orts (refused feed) 82 8.7 Average daily gain (ADG) and ad libutum intake of sheep fed test rations, and apparent dry matter digestibilities (DMD) of the complete rations 83 8.8 Apparent dry matter digestibilities (SDMD), apparent neutral detergent fiber digestibilities (SNDFD) and apparent acid detergent fiber digestibilities (SADFD) of pulp mill waste silages .... 83 8.9 Predicted digestible energy (DE) intake of rations containing 100% of pulp mill waste (PFW) silages (on a dry matter basis) 94 9.1 Dry matter proportions (%) of the ingredients used in the Prince George pulp mill waste (PG PFW) barley-^whey silage treatments ... 97 9.2 Chemical composition of ingredients (on a dry matter basis) used in Prince George pulp mill waste (PG PFW) barley-whey-urea silages and in the complete rations fed to ewe sheep 101 9.3 Chemical composition of pulp mill waste silage effluent 101 9.4 Concentration (molar percentage) of volatile fatty acids in pulp mill silage effluent 102 9.5 Chemical composition of pulp mill waste silages after ensiling (on a dry matter basis) 102 9.6 Chemical composition of Prince George barley-whey pulp mill silage rations fed (on dry matter basis) 103 9.7 Voluntary intake (on a dry matter basis) of sheep fed PG PFW barley-whey-urea silages 104 9.8 Average daily gain (ADG) and apparent dry matter digestibilities (DMD) of test rations 105 9.9 Apparent digestibility of dry matter (SDMD) and acid detergent fiber (SADFD) of barley-whey-urea PFW silage 105 10.1 Dry matter proportions of ingredients in pulp mill fiber waste (PFW) silage rations fed to dairy heifers 117 10.2 Average daily gain (ADG) and ad libitum intake of dairy heifers consuming rations containing pulp fiber waste (PFW) silage 119 11.1 Proportions on a dry matter basis of ingredients in rations fed to beef steers 125 ix L I S T OF T A B L E S ( c o n t ' d ) 11.2 Dry matter composition (%) of Prince George and Kamloops pulp mill fiber wastes 126 11.3 Composition of the Prince George pulp mill waste (PG PFW) and Kamloops pulp mill waste (PG PFW) mixtures before and after ensiling (on a dry matter basis) 128 11.4 Concentration of individual volatile fatty acids in the Prince George and Kamloops pulp mill waste silages 128 11.5 Dry matter composition of test rations 129 11.6 Total dry matter digestibility coefficients of test rations .... 130 11.7 Average daily gain (ADG), ad libutum dry matter intake (FI) and feed conversion (F/G) of beef steers during 63 days 130 11.8 Average weekly weights (kg) and standard deviations of beef steers fed control and rations containing pulp fiber waste silage . 132 11.9 Linear models and coefficient of determination (r 2) for average animal weights for a control ration and rations containing pulp mill waste silages during a 63 day feeding period 132 11.10 Estimated digestible energy intakes of the rations fed to beef cattle 140 12.1 Mineral profiles of pulp mill fiber waste 142 13.1 Concentration of resin acids and chlorinated compounds in the Prince George and Kamloops pulp fiber wastes 148 13.2 Dioxin and furan detection levels and concentrations in the pulp mill fiber wastes (PFW) 149 13.3 Number of revertant colonies 1 of Salmonella typhimurium induced by pulp fiber waste extracts '. 150 13.4 Method detection levels of analyses of dioxins and furans in beef livers 151 14.1 Assumptions pertaining to the cost of PFW and whey 158 14.2 Cost of ingredients and total ingredient cost of pulp mill fiber waste (PFW) barley-whey-urea silage 158 14.3 Costs of ensiling pulp mill fiber waste, other than ingredient costs 159 14.4 Total cost of pulp mill fiber silage 159 14.5 Cost of a pulp mill fiber (PFW) ration containing 22% PFW, an equivalent of 30% PFW silage for a herd of 50 beef steers for 75 days 160 LIST OF TABLES (cont'd) X 14.6 Cost of a pulp mill fiber (PFW) ration containing 44% PFW, an equivalent of 60% PFW silage for a herd of 50 beef steers for 75 days 160 14.7 Cost of a barley-alfalfa hay ration for a herd of 50 beef steers for 75 days 161 14.8 Summary of total cost of feed for a herd of 50 beef steers for 75 days using Ag Bags or bunker silos for ensiling 161 Al Recoveries (%) of volatile fatty acids after steam distillation using the Markham s t i l l 184 A2 Direct injection of a sample via a Sep-Pak f i l t e r onto the gas chromatcigraph 184 Bl Mean dry matter digestibility coefficients (DMD) of pulp mill fiber waste silage as determined by total fecal collection (FC) and by acid insoluble ash (AIA) as a natural internal marker 187 XI LIST OF FIGURES Chapter, figure Page 2.1 The linear structure of cellulose 4 2.2 Prominent structures in softwood lignin 6 2.3 Structural formulae of some resin acids and chlorinated guaiacols 7 4.1 Flowchart of the kraft pulping process 25 4.2 Flowchart of the solid waste disposal route at Weyerhaeuser Canada Ltd., Kamloops, B.C 28 4.3 Flowchart of the waste disposal system at Canfor Ltd., Prince George, B.C 29 5.1 The structural formulae of (a) polychlorinated dibenzodioxins and (b) polychlorinated dibenzofurans where x and y refer to the number of attached chlorine molecules 39 7.1 Possible schematic model of the breakdown of the carbohydrate fractions in pulp mill waste silages during fermentation 70 7.2 Water soluble carbohydrate (SCHO) content (as percentages of the total dry matter) in pulp mill fiber waste mijctures before and after ensiling for 70 days 71 8.1 Gas production rates by 100 grams of Kamloops barley-whey pulp fiber waste silage-alfalfa hay substrate at various temperatures over a 206 hour incubation period 86 9.1 Average daily silages tenperatures of barley-urea Prince George pulp mill fiber waste silages ensiled different levels of whey . 100 10.1 Dry matter intakes of the 30% and 60% pulp fiber waste (PFW) silages consumed by 77-90 kg dairy heifers during a 17 day feeding period 118 11.1 Air, Prince George pulp mill waste silage (PG PFW silage), Kamloops pulp mill waste silage (K PFW silage) temperatures taken over a 80 day period 127 11.2 Average weekly weights of long yearling beef steers over a twelve week feeding period on control and pulp mill fiber waste silage rations 133 11.3 Comparison of feed conversion (feed/gain) between treatment groups, and the differences in average daily gain (ADG) and ad libitum intake between the control and pulp mill fiber waste rations fed to Hereford-cross long yearling beef steers 137 14.1 Distribution of kraft pulp mills in relation to cattle grazing areas in British Columbia 157 x i i ACKNOWLEDGMENTS The idea behind and beginning of this project belong to Mr. David Croy and Dr. Lyle Rode, who passed onto me a unique and exciting opportunity. To them and to the many friends and colleagues who made invaluable contributions to this project, I am grateful. In particular, I would like to thank the managers and staff at Prince George Pulp and Paper, Division of Canfor, Ltd., Prince George, B.C. and Weyerhaeuser Canada Ltd., Kamloops, B.C. for supplying the mountains of pulp mill fiber waste, Mr. Mike Yusko and Fraser Valley Milk Producers for supplying the whey, and Mr. and Mrs. Fred Hopcott of Pitt Meadow Feedlot for graciously providing the beef steers. Thank you to the staff at Agriculture Canada, Prince George Research Station for the use of the fac i l i t i e s , for their help and their direction during the early phases of the project, and to Mr. Ted Cathcart and Mr. Paul Willing for their contributions towards the beef cattle t r i a l conducted at South Campus at U.B.C.. Also, thank you to Drs. Eldon Reynolds, Tim Munshaw, Jim McKinley, Ernie Lee, Mr. John Zagar and Mrs. Kathy Buckley for their technical expertise, and to Mr. Harold Johnson, Mr. Marcus Janzen, Mr. Shenton Tan and Mr. Shane Gumprich who provided the necessary sweat and technical assistance to complete a project without which would have been impossible. I would also like to extend a sincere thank you to Mr. Neil McDonald for his wonderful insight, Dr. Heinrich Binder for his patient assistance in the statistical analyses, Dr. Alejandro Vera for his wealth of ideas, and Dr. Murray Drew for his cooperation, understanding and numerous peptalks. Also I would.like to thank Mrs. Merry Carol Scholberg and Ms. Myrna Bilawchuk, who kindly proof read this manuscript. I am indebted to the members of my cranmittee, Drs. Jim Shelford, David Kitts, Malcolm Tait, CR. Krishnamurti, Lome Fisher, and my advisor, Bruce Owen for their expertise, enthusiasm, and patience to see the project through to i t s end. Finally, I am grateful to God for His constant provision of strength and grace. This study was supported by a grant from the British Columbia Science Council. x i i i This thesis i s dedicated to Ms. Irene Schuurman and Ms. Karen Stever who laughed and made me laugh even when while enveloped by the distinct odor of pulp mill fiber waste. Their skilled analytical assistance and loyal friendships made the work easier and at times, even fun. 1 CHAPTER ONE 1.0 INTRODUCTION With shortages and rising prices of raw materials, i t i s necessary to use existing resources with more efficiency and conservation. In British Columbia the kraft process is the most common method of producing pulp. Compared to other pulping methods, kraft pulping maximizes fiber quality and minimizes cost by recycling chemicals (Sjostrom, 1977). In 1986, British Columbia produced 6.2 million tonnes of pulp, while simultaneously discharging billions of cubic meters of waste water and than 62,000 - 124,000 tonnes in dry matter of residual pulp mill fiber waste (PFW). Alternative routes to the mere disposal of PFW have been investigated. PFW has been identified as a possible cheap substitute for conventional feedstuffs. In particular, Cray and Rode (1988) have shown cellulosic PFW from kraft pulp mills in British Columbia to be potential ruminant feedstuff. PFW, a byproduct of pulping and bleaching processes, has been partially exposed to various treatments within the mill. The potential energy contained in the original raw wood i s then made available to both the rumen microflora and the host. However, this treatment can not leave any residues or inhibitors in the PFW which would be toxic or have deletirous effects on the microflora of the host or the host itself, which would defeat the usefulness of the PFW as a feed. Aside from heavy metals contamination (Baker et al . , 1975; Cray and Rode, 1988; Nicholson, 1981), the presence of residual chemicals from the bleach kraft process present in the PFW or paper related products has not been investigated. However, to date no clinical 2 symptoms or indications of deleterious substances have been associated with the feeding of PFW. In this study, the suitability of PFW as a feed in terms of i t s handling and storage properties, i t s nutritional value, and i t s effect on animal production were examined. In addition, in order to assess the suitability of PFW as a feed for beef cattle, PFW was examined for potential toxic compounds, and the economic merit of PFW as a feedstuff was evaluated. 3 LITERATURE REVIEW CHAPTER TWO 4 2.0 WOOD COMPOSITION A fundamental understanding of the composition of wood and i t s degradation products in the manufacture of pulp i s c r i t i c a l in understanding the nutritive cuiipunents as well as the contaminants present in pulp mill fiber waste (PFW). Cellulose, hemicellulose, lignin and various extractives are the main components of wood. Composition varies with species. The kraft pulping process i s nonselective in the removal of lignin, resulting in high carbohydrate losses (Sjostrom, 1977). More than 20% of the total wood polysaccharides are lost during the kraft process (Sjostrom, 1977). During the kraft pulping of pine wood when 5% of the total lignin is removed, more than 15% of the roilignin material i s lost from the original wood (Sjostrom, 1977). 2.1 CELLULOSE On a dry matter basis, forty percent of most wood i s cellulose (Kringstad and Lindsfcram, 1984). Cellulose, a linear unbranched polysaccharide which consists of (1,4) -glucosidic linked fl-D-glucopyranose units (Figure 2.1). These units repeat so that the molecular weight of Figure 2.1 The linear structure of cellulose 5 cellulose i s greater than 10,000. Cellulose molecules form microfibrils which make up the f i b r i l s that comprise cellulose fibers. In ruminants, the 6 1-4 linkages in cellulose are broken, so the glucose monomers can be utilized by the microflora and ultimately by the host. 2.2 HEMICELLULOSE Unlike cellulose, hemicelluloses are lower molecular weight branched pentoses. Hemicelluloses are amorphous polysaccharides which include short chain glucans, polymers of xylose, arbinose, mannose, galactose and uronic acid polymers (Pigden and Heaney, 1969). The types and proportions of hemicelluloses differ between softwoods and hardwoods (Kringstad and Lirristram, 1984). Glucamannons found in softwoods and xylans found in hardwoods are the dominant hemicelluloses (Elgee, 1975). 2.3 LIGNIN Ldgnin is generally resistant to enzyme action and i s therefore poorly digested. Lignin, present in the fiber walls and the middle lamella, binds the cellulose fibers together providing strength and rigidity to plant walls. Lignin, a noncarbohydrate material, is a branched aromatic polymer formed by the enzyme-initiated dehydrogenative polymerization of three different 4-hydroxyarylpropeny1 alcohols (Figure 2.2) (Kringstad and Lindstrom, 1984). The basic monomeric unit is phenyl propane (Elgee, 1975). The proportions of the precurser alcohols vary with the wood species. Coniferyl alcohol is the primary precursor of softwood lignin. A variety of water soluble substances, phenolic in nature, can result from lignin degradation (McKean, 1980). 6 2.4 E X T R A C T I V E S Compounds which can be extracted from the wood with an organic solvent are termed "extractives". The aliphatic extractives include fats and waxes. Terpenoid compounds are unique to softwoods and include terpenes and resin acids (Figure 2.3). Phenolic extractives include hydrolyzable tannins, flavonoids, lignans, stilbenes and tropolines. The total content of extractives (1.5-5% of the wood) (Kringstad and Lindstrom, 1984) and the proportion of specific chemicals in the wood varies with species, location, age and section of the tree. 0EHYDROABIET1C A8IET1C NE0A8IET1C 4A6-TTRlCHLCflC<3UAlflCOL 3,4,5-TTRlCHLOROGUAlACOL TETRACHLOROGUAIACOL Figure 2.3 Structural formulae of some resin acids and chlorinated guaiacols CHAPTER THREE 8 3.0 THE FEEDING OF PULP MILL FIBER WASTE 3.1 H i s t o r i a l perspective Forests are a storehouse of carbohydrates, although as ratural feed resources the cellulose and hemicellulose have limitations. Although cellulose and hemicellulose make up about 70% of the dry matter of most shrubs and trees, wood and wood products are virtually indigestible (Pigden and Heaney, 1969; Baker 1973). Of the carbohydrates present in whole wood, only a minor fraction are accessible to rumen microorganisms (Millett et al. , 1973). The limited digestion of the wood in the rumen has been attributed to the molecular structure and the association of lignin with cellulose and hemicellulose (Van Soest, 1969; Mellenberger et al . , 1970). Substitutes for animal feeds become more important when traditional forages and roughages are expensive or in short supply. Interest in wood and associated products as feed sources was sparked by World War I when feed grain prices were high. Since that time, various methods of treating wood to increase the accessability of carbohydrates have been proposed. Kitts et a l . (1969), Pigden and Bender (1972), Baker et al . , (1975) and Nicholson (1981) have reviewed possible methods of increasing the energy digestibility of low quality forages and lignocellulosic wastes. Such methods included mechanical (chopping, grinding, compressing), physical (irradiation, heat extrusion, steam processing), chemical (alkali and acid treatments) and microbiological treatments. However, in most cases the costs of processing the wastes prevented any practical application. Softwoods have 25-50% more lignin than hardwood. In vitro rumen studies have shown that a l l softwoods were essentially nondigestible, while hardwoods were partially digestible. The respective dry matter 9 digestibilities of raw softwood and hardwood generally range from 0-5%, and from 2-37% (Mellenberger et al., 1970; Millett et al., 1973). Further changes in the digestibility of wood and wood products depend on the quantity of lignin removed and not on the method of removal (Baker, 1973; Baker et al . , 1975). Although wood and wood products have been incorporated into beef cattle rations, preliminary physical and/or chemical treatments appeared necessary to enhance the wood's digestibility (Kitts et al. , 1969). In the case of wood pulp and paper wastes, the lignocellulose wastes have been subjected to physical and chemical treatment during the pulping process which acts as a "ratural pretreatment". The conversion of wood to pulp causes partial delignification. The remaining cellulosic products or wastes can then be exploited as a ruminant feed with minimal additional processing or cost. The accessibility of wood carbohydrates to rumen microorganisms and their associated enzyme systems was shown to increase after delignification (Mellenberger et al. , 1970; Baker, 1973; Millett et al., 1973). The incorporation of pulp fiber waste (PFW), a byproduct from the production of bleached and unbleached kraft pulp, into cattle rations is not a new idea. In 1920, hydrolyzed sawdust was fed to animals at the University of Wisconsin and at the US Department of Agriculture in Beltsville, Md. (NRC, 1983). During World Wars I and II, sulfate and sulfite wood pulps were consumed by cows and horses due to high feed prices and feed shortages (NRC, 1983). 3.2 Wood products as roughage substitutes Much research has gone into utilizing the vast quantities of residue from logging, lumber and plywood manufacturing, and the pulp and paper irxlustry. These residues as well as pulp sludges, sawdusts and raw wood 10 products have generally been incorporated at low levels i n experimental rations as roughage substitutes. Ruminants need same fibrous feed i n their rations. Indigestible fibrous wood plays a non-nutritive role by providing t a c t i l e stimulation necessary for rumen function (Baker et a l . , 1975; Dinius et a l . , 1970). However, when raw sawdust was incorporated i n ruminant rations at more than 15%, intake and weight gain were depressed (Anthony et a l . , 1969; K i t t s et a l . , 1969). Yet, roughage substitutes including sawdust, wood shavings, karolin clays and sugarcane bagasse, when incorporated at 10% i n sheep rations, tended to increase the d i g e s t i b i l i t y of the concentrate fraction (Dinius et a l . , 1970). Anthony et a l . (1969) concluded that waste wood i t s e l f added l i t t l e or no energy i n steer finishing rations. However, paper products, when incorporated i n small amounts i n sheep rations, had beneficial effects on intake and weight gain (Coombe and Briggs, 1974). Thus, Coombe and'Briggs suggested that paper did not act i n the same way as conventional roughage i n the rumen despite s i m i l a r i t i e s i n chemical composition and rumen fermentation products. Animals fed a ration of 75% aspen pulp m i l l fines (similar to PFW but rejected i n the pulp process due to small p a r t i c l e length) exhibited a craving for roughage. Wood shavings had to be used to prevent consumption of bedding material (Fritchel et a l . , 1976). Lemieux and Wilson (1978) also suggested that pulp m i l l f i b e r waste had l i t t l e or no value as a roughage. Both Fritschel et a l . (1976), and Lemieux and Wilson (1978) recommended pulp residue rations be supplemented with 10-12% of a "standard roughage11. 3.3 Chemical composition The composition of pulp fiber wastes from various pulping processes represents a substantial loss i n l i g n i n and hemicellulose from the content of 11 the original raw wood. On a dry matter basis, pulp mill fiber wastes consist primarily of cellulose and complex hemicelluloses (Lemieux and Wilson, 1979; Cray and Rode, 1988). Chemical compositions and energy digestibilities of pulp mill wastes were variable (Mertens and Van Soest, 1971; Millett et al . , 1973). Very small amounts of crude protein (< 2%) were reported in PFW (Clark and Dyer, 1973; Fritschel et a l . , 1976; Lemieux and Wilson, 1979; Cray and Rode, 1988). Since PFW i s low in nitrogen and other essential nutrients required by livestock, same form of protein and mineral supplementation is required in any PFW ration (Lemieux and Wilson, 1978; Cray and Rode, 1988). The ash constituents of pulp residues were also variable (Lemieux and Wilson, 1979). The mineral content of the pulp residues reflected their exposures to chemical processing (NRC, 1983). Millett et a l . (1973) reported 1.8-17.4% ash in different hardwood sulfite pulp residues. Cray and Rode (1988) indicated that wide variations in chemical composition of kraft pulp mill fiber wastes from different pulp mills in British Columbia was similar to that reported for American kraft pulp mill fiber residues (Baker, 1973; Millett et al . , 1973; Croy and Rode, 1988). Pulp mill fiber wastes are high moisture materials (Croy and Rode, 1988). The dry matter content ranged from 15.6-35.2%, the organic matter from 42.5-96.3%, and the lignin content from 2.2-50.7%. Several PFW samples also contained sufficiently high levels of calcium, sodium, aluminum, cadmium and lead to be of concern i f PFW was used as a feedstuff. The possibility of toxicity exists that levels of minerals such as aluminum and cadmium could restrict the use of pulp mill fiber waste in ruminant diets (Croy and Rode, 1988). 12 3.4 D i g e s t i b i l i t i e s of paper and pulp m i l l f i b e r wastes Because o f t h e s i m i l a r i t i e s i n chemical c o m p o s i t i o n and p r o c e s s i n g o f PFW and paper, t h e v a l u e o f paper as a f e e d s t u f f , p a r t i c u l a r l y i t s d i g e s t i b i l i t y , i s b r i e f l y reviewed. Wide v a r i a t i o n s e x i s t e d i n t h e i n v i t r o d i g e s t i b i l i t i e s o f newspapers, t y p i n g papers and computer papers (Coombe and B r i g g s , 1974). D i g e s t i b i l i t y appeared t o be n e g a t i v e l y c o r r e l a t e d w i t h l i g n i n c o n tent and p o s i t i v e l y c o r r e l a t e d w i t h c e l l u l o s e c o n t e n t , a l t h o u g h t h e d i f f e r e n c e s were not s i g n i f i c a n t . T h i s was p r o b a b l y due t o t h e s u b s t a n t i a l v a r i a t i o n o f t h e d i g e s t i b i l i t i e s o f t h e d i f f e r e n t k i n d s o f paper (Coombe and B r i g g s , 1974). V a r i a b i l i t y i n paper, e s p e c i a l l y n ewsprint, was p a r t i a l l y e x p l a i n e d by t h e p r o p o r t i o n s o f ground wood and chemical t r e a t e d p u l p p r e s e n t (N i c h o l s o n , 1981). However, i n v i t r o d i g e s t i b i l i t y v a l u e s i n d i c a t e h i g h - q u a l i t y papers and,brown paper c o u l d be v a l u a b l e energy sources (Mertens and Van Soest, 1971; Coombe and B r i g g s , 1974). Other -types o f newspaper were l e s s d i g e s t i b l e , and were suggested t o be used i n low energy maintenance r a t i o n s (Coombe and B r i g g s , 1974). Other s o l i d c e l l u l o s i c wastes c o n t a i n i n g o n e - t h i r d paper, d e s p i t e t h e h i g h n e u t r a l d e t e r g e n t f i b e r c o n tent (76.8-95.2%), had i n v i t r o d i g e s t i b i l i t i e s r a n g i n g from 28.6-45.5% (Belyea e t a l . , 1979). I n r a t i o n s where paper was i n c o r p o r a t e d , t h e r e was a s i g n i f i c a n t n e g a t i v e c o r r e l a t i o n between c e l l u l o s e i n t a k e and d i g e s t i b i l i t y ( r = -0.68) (Coombe and B r i g g , 1974). The d r y m a t t e r d i g e s t i b i l i t i e s o f t h e p a r t i a l l y d e l i g n i f ed pulp' m i l l f i b e r wastes, although o f t e n q u i t e h i g h , were v a r i a b l e (Baker e t a l . , 1975; Mertens e t a l . , 1971; C l a r k e t a l . , 1971; D i n i u s e t a l . , 1975). PFW had i n v i t r o d r y m a t t e r d i g e s t i b i l i t i e s o f 45-60% up t o a maximum o f 96% ( M i l l e t t e t a l . , 1973; Baker, 1973; D i n i u s and Bond, 1975). Cray and Rode (1988) assessed t h e n u t r i t i o n a l v a l u e o f p u l p m i l l f i b e r wastes from B r i t i s h Columbia p u l p m i l l s i n s i t u and i n v i v o , and concluded t h a t spruce/pine PFW 13 produced in the interior of BC had positive effects on digestibility when mixed with grass-legume silage. Rations with 48% PFW had a maximum digestibility compared to rations with lower levels of PFW. As well, increasing levels of PFW in rations were positively correlated with increasing digestibilities in dry matter, nitrogen and acid detergent fiber (Croy and Rode, 1988). These results contradicted Lemieux and Wilson's findings which showed when increasing amounts of PFW were fed to sheep, the dry matter digestibility decreased. Other in vivo studies with sheep, goats and cattle showed the digestibilities of same wood and pulp residues were comparable to that of good quality hay (Millett et al. , 1973). In general, wood pulp had a high digestibility when acid detergent fiber levels were high (Dinius and Bond, 1970) and the lignin content was below 5% (Baker, 1973). 3.5 Animal performance t r i a l s When steers consumed 50-70% of their total ration as PFW, their average daily gain (ADG) varied between 0.5-0.74 kg/day (Baker et al. , 1975; Dinius and Bond, 1975; Clark et al. , 1971). Millett et a l . (1973) reported forage fed controls gained significantly more weight than growing steers fed 50-70% PFW. Dinius and Bond (1975) also showed that growing beef heifers fed 50% sulfite pulp fines had higher gains than heifers fed a control ration. The performance of growing animals was poorer when wood residues were substituted for alfalfa or grain in the ration (Fritschel et al. , 1976). The NRC (1983) recommended PFW as a feed for animals with low nutrient and energy requirements. This reconmendation was based on the chemical composition of PFW and the satisfactory average daily gains of the animals consuming PFW. The NRC (1983) recommended that treated wood residues were best suited for overwintering beef cows, ewes, "dry" dairy cows and 14 replacement heifers. Cray and Rode (1988) indicated that PFW could be a potential forage substitute based on digestible dry matter intake. Performance data from Riquelme et al . (1975) indicated that the energy obtained from cellulose fiber was about 85% that of barley, and could be used successfully as an energy source in lamb fattening rations. When PFW was fed to pregnant beef heifers, no difference in ADG, calf birth weights or calving problems were observed compared to hay fed heifers (Dinius and Bond, 1975). Variations in rumen pH, volatile fatty acid concentrations (Millett et al. , 1973) and microbe populations (Clarke et al., 1971) were not significantly different between PFW and hay fed steers. However, the rumen pH tended to decrease and the volatile fatty acids (especially propionate) increased (Millett et al., 1973). The amount of change in VFA concentrations in the rumen depended on the amount of PFW in the ration and the chemical processes to which the pulp had previously been exposed (Baker et al . , 1975; Dinius and Bond, 1975). Dinius and Bond (1975) showed that VFA concentrations differed significantly between PFW and hay fed animals with the PFW fed animals having a lower acetate to propionate ratio compared to the hay fed animals. Clark and Dyer (1973) showed that animals fed 70% sulfite processed Douglas f i r had larger proportions of acetate and a lower percentage of propionate in their rumens than the control barley fed animals. PFWs had no adverse affects on carcass merit (Clark et al . , 1971; Riquelme et al., 1975; Lemieux and Wilson, 1979), or on rumen or liver histology (Millett et al., 1973; Lemieux and Wilson, 1979). Rations containing 50-75% PFW have been readily consumed by steers and sheep without any unusual digestive or metabolic disorders. In the cases reported, animals eating PFW rations were not observed to bloat or to go off feed except when PFW was incorporated at very high levels. Sheep fed 84% newspaper rejected their ration almost completely and were taken off that 15 particular ration after two weeks (Coombe and Briggs, 1974). Lemieux and Wilson (1979) removed five lambs (four were on PFW diets) from their digestibility t r i a l . One lamb, in particular, fed 40% PFW was removed because of loss of appetite, substantial feed refusal and sorting of diet ingredients (Lemieux and Wilson, 1979). In other feeding t r i a l s the animals i n i t i a l l y found PFW unpalatable but after a short adjustment period, the ration was readily consumed (Croy and Rode, 1988). Growth rates were acceptable. Levels of essential nutrients were maintained so that normal reproduction and growth of nursing offspring occurred (Baker et a l . , 1975). 3.6 Production and u t i l i z a t i o n Wood pulp and paper wastes are attractive sources of feed because of their localized concentration. The kraft process is the most common method of producing softwood pulp in British Columbia (Mies, 1981). On a wet matter basis, more than 15 million tonnes of pulp mill fiber wastes from kraft pulped softwood are produced each year in British Columbia (Croy and Rode, 1988). In the US, for each metric ton of wood pulp produced, an average of 40 kg of fiber residues are produced (Millett et al. , 1973). Of the eleven pulp mills in BC, none recycle a l l their pulp residue. A direct and urgent need for conversion of pulp waste into other useful products exists. The pulp waste residue is commonly burned or used as landfill as a main disposal method. However, this practice is costly, ecologically unsatisfactory and a waste of potentially valuable carbohydrates. Table 3.1 summarizes the work done with respect to the nutritional aspects of pulp mill fiber wastes. Much of the research in this area has been done in the southeastern United States. As a result, this data pertained to sulfite versus kraft mills, unbleached versus bleached pulp, and hardwood, in particular, aspen, versus softwood. When softwood pulp was 16 evaluated, the source was either Douglas f i r or southern pine. Large variations existed in the composition of PFW depending on the wood species, the pulping process and the purification (extent of bleaching) of the pulp. A l l these factors varied with the mill itse l f (Dinius and Bond, 1970). Lignin, carbohydrate and ash content were common parameters used for comparison. Most studies were conducted in short term periods. Studies utilizing a large number of animals over a prolonged feeding period need to be conducted to determine any nutritional deficiencies or problems associated with residues. In the past sheep or goats have been used as indicators of palatability and digestibility for pulp mill waste. Sheep and goats tend to be selective browsers. Cattle are more capable of digesting low quality fibrous feeds (Van Soest, 1982). In the central interior of British Columbia where grain prices are high and hay making weather unpredictable, pulp mill waste is abundant, and a large cattle population exists. Here, PFWs have the potential to be a viable feedstuff for beef cattle. Generally raw forest product wastes have limited potential as energy sources in spite of high carbohydrates levels. However, the high digestibilities of PFWs from pulp mills in the interior of British Columbia indicated that these PFWs may be a potential energy source for beef cattle (Cray and Rode, 1988). Given the number of varying factors in composition and pulping procedures, and the potential contamination of extraneous chemicals from the pulping process and mineral imbalances (Chapter 5.0), recommendations on the suitability of the specific PFW in question is dif f i c u l t without more complete chemical analyses and animal performance tr i a l s . Table 3.1 Summary of the literature on the nutritional aspects of paper and pulp mill fiber wastes PRODUCT COMPOSITION NUMBER OF ANIMALS, SPECIES FORM FED RESULTS REFERENCE 11 piper sources, 3 coiplete feeds -brown wrapping piper and brown cardboard had an in vitro dry utter disappearances of 83.il and 71.81. -waste papers with the lowest dry litter digestibility had high lignin (<20X) and low cellulose U55X). Mertens et il. 1971 38 paper sup l i t brown paper newsprint wood pulp froi Douglas Fir -ash 0-201; lignin 0-301 -ash <2Zj lignin 10X -ash IX; lignin 20-251 N»24, 332 kg Hereford cattle -82.SX barley control -50X wood pulp ration -70X wood pulp ration bleached spruce sulphite pulp -in vitro digestibility 21-98X Mertens and -in vitro digestibility 8S-95X Van Soest -in vitro digestibility 25-40X 1971 -dry latter intakes 7.86-9.40 kg, Clark average daily gain 1.34-1.75 kd/D, et il. feed efficiency 3.30-7.IS. 1971 -control carcasses graded 'choice*; pulp carcasses graded 'high good' -in vitro dry latter digestibility wast Pigden and 8.0X at 12 hrs., 31.SX at 24 hrs., 72X at Bender 36 hrs., 91.OX at 48 hrs., 100X at 72 hrs. 1972 continued. PRODUCT COHPOSITION NUMBER OF FORM FED AN!HALS, SPECIES RESULTS REFERENCE Douglas fir wood ihridded to 1-2 inchu in length, pulped with auonia sulfite. aspen sulfite l i l l screen rejects ispen unbleichid sulfite sill fines •ixed hardwood, bleached kraft pulp unbleached kraft southern pine N'12, Hereford steers -781 barley control, 701 wood pulp ration •126 days -Net pulp stored in uncovered concrete pits -No significant difference in average daily Clark and gain: 0.S9 kg/D for wood ration and 1.07 kg/D Dyer for the control. 1973 -feed conversion: 3.89 for the control, and 10.38 for the nood ration. -intake: 6.29 kg/D on the control rations, and 6.20 kg/D on the wood ration. -hexose energy in the 701 nood ration Mas converted to volatile fatty acids uith 91 less efficiency than that of the barley diet. N»3, -chroiic oxide larker -dry latter, acid detergent fiber and gross energy Hereford steers in 70Z wood ration digestibilities: 33.311, 62.871, 54.38Z NM, 40-50 kg Saanin goats NM, yearling Herefords -fed at 21 of body Might -0-631 of ration -in vitro digestibility 661; lignin 191} CHO 771 Hillett -in vitro digestibility 731; lignin 201; CHO 731 et tl. •in vitro digestibility 951; lignin <1Z; CHO 11 1973 -in vivo digestibility 431; lignin 221; CHO 731 -concentrations of auonia and volatile fatty acids increased uith level of PFW in diet NMO, 226 kg Hereford cattle -0 or 301 PFa -38 day trial -ad Jioutui intake -control aniials gained tore weight (0.77 versus 0.34 kg/D); control aniials consuied lore feed (2.84 versus 2.481 of body weight); control aniials had had better feed conversion ratios (9.44 versus 11.69); differences in intake and feed conversion were not significant. continued. PRODUCT COMPOSITION NUMBER OF FORM FED RESULTS ANIMALS, SPECIES REFERENCE unbleached aspen sulfite till parenchyia cells 10 cheiical pulps 2 iichanical pulps 6overnaent Mists piper N-30, nonpregnant ewes N«9, 2 yr old crossbred •ethers -77.41 PFW -77 diy trill -id lisutui intake -pelleted ritions containing 451 mite piper -intike 1.5-1.8 kg/D -21 anietli gained Might; 9 anieals lost weight overall Might change 0.056 kg. -in vitro digestibility 67-981 -in vitro digestibility 0-71 -fungus, fapirgillut fu»igitu$ grew on pulps with low lignin content -average daily gaim 0.177 kg -in vitro digestibility: 52.51 Baker tt il. 1973 Caoibe and Brigg 1974 N»1B, 7 eonth old crossbred ewes -ad libitui intake of pelleted 6overneent waste paper, paper/newsprint, or lucerne fed control -pellets contained 841 paper -organic latter and cellulose digestibilities were higher in paper diets than in the control rations. -sheep on the 84X newsprint ration rejected diet completely, and were taken off ration after 2 weeks continued. PRODUCT COMPOSITION NUMBER OF ANIMALS, SPECIES FORM FED RESULTS REFERENCE unbleached hardwood fiber fragients froa auonia bated sulfite aill bleached kraft hardwood, and bleached sulfite aixed wood cellulose fibers N«3, ruien fistulated steers NM5, 264 kg Angus beef heifers N«9, pregnant beef heifers N'30, 42 kg white face wethers -651 PFN -fed at 1.5X of body weight -2B days trial -461 PFN -99 day trial -73.11 PFN -209 day trial -921 NDFj 80.71 ADF; 3.31 acid detergent lignin} Dinius and 1.6Z crude protein) 2.31 ash Bond -cellulose was 92.81 digestible. 1975 -ruien pH was significantly lower, and VFA concentration higher than orchardgrass fed control aniials. -PFN fed aniials gained significantly tore weight than control aniials (0.74 versus 0.47 kg/D); no significant difference in intake (3.211 versus 2.811 of body weight); no significant difference in feed conversion ratios existed (16.99 versus 12.93). -no significant difference in weight gain, calf birth weight, or calving probleis between PFN including parturition control fed aniials. -601 alfalfa/401 concentrate control -2 rations containing 661 of the 2 types of fibers -76 day feeding trial -no difference in average daily gain 0.15-0.18 kg. -the intake on the fiber rations was less than on control rations (1.33-1.78 kg), -the fiber rations had a better feed conversion the control rations (8.37-9.88) -control laibi exhibited higher dressing percentages and backfat thicknesses than fiber fed laibs. -no statistical difference in carcass grades Riquelie tt il. 1975 continued. PRODUCT COMPOSITION NUMBER OF ANIMALS, SPECIES FORM FED RESULTS REFERENCE bleached lixed wood sulfite N«40, 32 kg -701 barley control -laibs consuming the control ration had a higher Riquelie cellulose fibers white face -3 test rations average daily gain than those consuling the ft al. wethers containing sulfite fiber rations (0.16-0.23 kg). 1975 fiber and different -feed efficiency was best in the fiber-soybean nitrogen sources •eal ration, and lowest in the fiber-roughage -70 day trial ration (6.73-8.23). -control laibs had a higher dressing percentage, greater aaounts of backfat, kidney and pelvic fat, and lower carcass grades and yield grades than fiber fed laibs. aspen bark and aspen pulp aill N«45, 3-6 yr -alfalfa hay control -ewe perforianci siiilar and satisfactory in Fritschel fines froi an auonia-based old western -pelleted test all groups it al. sulfite tissue t i l l white face rational 72.51 pulp 1976 ewes fines, and 72.31 aspen bark N>4, -rutin ingesta fro* iwn fid pulp fines and fistulated ewes bark had a pH « 6.3. -ruiinal ular percentages for acetate, propionate, and butyrati were 71.0, 18.8, 7.2. N-20, 223 kg -alfalfa haylage -average daily gain (kg)t control 1.09, Angus-Hereford and hay control pulp 0.45. steers -731 pulp fines in -intake (kg): control 8.50, pulp 7.68 test ration -feed convarsioni control 7.8, pulp 17.1 -101 day feeding trial N»9, Angus -a ration of 831 -cows consuaed pulp ration readily beef cows pulp fines and -perforaance of tested aniaalt expected alfalfa hay to equal that on conventional feed rations. -7 aonth trial continued... PRODUCT COMPOSITION NUMBER OF FORM FED RESULTS REFERENCE ANIMALS, SPECIES ispen bark and atpen pulp t i l l fines froi an auonia-based sulfite tissue eill unbleached fiber residue froi a hardwood anonia based sulfite tissue eill NMO, 383 kg Hereford steers N«19, 34 kg Western white face x Dorset or Suffolk wethers -pelleted ration containing either oat hulls or pulp was coepared to corn silage during the 3 first weeks of a high grain finishing ration. -hay/corn control -3 test rations containing 20, 23, 40, 60, 671 pulp -weight changes were lowest with the pulp fed aniials but varied between 0.63-1.38 kg/D. -anieals readily consuisd all rations -crude protein 1.21) neutral detergent fiber 93.41; acid detergent fiber 86.41; acid detergent lignin 4.11; ash 1.3X. -no difference in intake. -apparent dry latter digestibility was highest (P < 0.01) in the 231 pulp diet, and lowest in the 671 pulp diet. -neutral detergent and acid detergent fiber digestibility was highest (P < 0.01) in the 601 pulp diet and lowest in the control diet. -nitrogen retention was highest in the control laibs and lowest (P < 0.03) in the 671 pulp fed laibs. Leiieux and Wilson 1979 continued. PRODUCT COMPOSITION NUMBER OF FORM FED ANIMALS, SPECIES RESULTS REFERENCE unbleached fiber residue froa a hardwood auonia based s u l f i t e tissue a i l l pulp n i l fiber wastes froa 10 s i l l s in B r i t i s h Coluibia pulp t i l l fiber waste froa B r i t i s h Coluabian kraft softwood NM8, 36 kg crossbred ewes and laabs N=6, yearling Hereford steers -54 day finishing t r i a l -nylon bags placed in 3 ruaen fi s t u l a t e d steers for 8, 12, 24 hr fed ttaothy hay -PFW was substituted for tmothy clover silage at 0, 12, 24 36, m of the total dry natter. -96 day d i g e s t i b i l i t y t r i a l -crude protein d i g e s t i b i l i t y was not s i g n i f i c a n t l y different between treatment groups, - f i n a l weight and average daily gain were lowest for laabs fed 60X pulp but no difference in the reaaining groups. -carcass t r a i t s were not affected by levels of pulp in ration. -no adverse effects of rations on blood urea nitrogen, protein and aineral levels, or ruaen and l i v e r histopathy. -dry aatter: 15.6-35. Croy and -organic aatter: 42.5-96.3! Rode - l i g n i n content: 2.2-50.77. 1988 -5 of the 10 saaples had in sacco d i g e s t i b i l i t i e s greater than 50L - D i g e s t i b i l i t y of the dry aatter (62.5-70.5X1, organic aatter (64.2-80.07.), acid detergent fiber (40.1-80.OX), and neutral detergent fiber (64.8-79.21) increased l i n e a r l y (P < 0.01) with increasing levels fo PFW in the diet. C H A P T E R P O U R 24 4 . 0 T H E K R A F T P U L P P R O C E S S The pulp process determines the composition of the PFW. Pulping separates the wood into discrete fibers, removes the lignin and improves the paper making qualities of the wood. The kraft process refers to the method of wood digestion. The manufacture of pulp via the kraft process i s outlined in Figure 4.1. Within the process, pulp washing practices and bleach plant operating conditions may differ widely between kraft mills (Leach et al. , 1978b). The final pulp product i s also influenced by the species of wood used (Leach et al., 1978b). In this study, the two pulp mills where the PFW was obtained used predanrinately different wood species in the manufacture of pulp. Weyerhaeuser Canada in Kamloops used a combination of sawdust and wood chips from pine, spruce, Douglas f i r , hemlock and cedar. Canfor in Prince George used white spruce, lodgepole pine, balsam f i r and Douglas f i r . 4 . 1 T H E D I G E S T I O N P R O C E S S A combination of heat (160°-180°C), pressure (500 psi) and white liquor (a solution of sodium hydroxide, sodium sulfide, sodium carbonate and sodium sulfate) cleaves the ether bonds in the lignin of the wood chips removing 90-95 percent of the lignin in the original wood (Kringstad and Lindstrom, 1984). The digestion process dissolves protein, extractives and more than 30% of the polysaccharides in the wood in the kraft pulp liquor (Kringstad and Lindstrom, 1984). Of the polysaccharides, mainly hemicellulose, other soluble sugars, and to a lesser extent cellulose are removed from the wood 25 | GRE f N LIQUOR \ | STEAM \ SCREENED WOODCHIPS 1Z3E j R E C O V E R Y B O l - E R S ] | CHEMICAL MAKEUP | E V A P O R A T O R S 1  j aiAOT LIQUOR **)• D I G E S T E R K N O T T E R S ' I < [ WHITE LIQUOR A 5 S T A G E B L E A C H M C BLEACH EFFLUENT nGK-oeerrv STOCK STORAGE B L O W T A N K B R O W N S T O C K W A S H E R S B R O W N S C R E E N S B R O W N D E C K E R 2 - 3 S T A G E S C R E E N S C E N T R I F U G A L C L E A N E R CHLORINE FIRST CAUSTIC CHLORINE DIOXIDE SECOND CAUSTIC CHLORINE DIOXIDE P U L P M A C H I N E C U T T M G P A G K A G X G S H P M E N T F t i S H E D P R O D U C T Figure 4.1 Flowchart of the kraft pulping process 26 during this digestion process (Sjostrum, 1981). A fibrous solid and liquid termed "black liquor" are left. Mechanical force in the blow tank fiberizes the predigested woody solid. The fiber is cleaned and screened. Evaporating and condensing the inorganics in the black liquor produces "green liquor". The remaining portion of the black liquor is burned to generate steam and power for the mill. Calcium carbonate and sodium hydroxide added to the green liquor produce a "white liquor" which recycles within the system. "Brown stock", the end product of the kraft process, i s a strong, brown product which serves as the base of many types of paper. Residual lignin makes the pulp dark colored and i f l e f t in the fiber causes paper to yellow easily with age or with sunlight (Van Strum and Merrell, 1987). The remaining 5-10% of the original lignin can not be removed with the kraft process without damaging the remaining cellulose fibers (Kringstad and Lindstrom, 1984) so a multistage bleaching system provides further delignification. 4 . 2 THE BLEACHING PROCESS Bleaching produces a strong, white pulp. The bleaching process involves a series of treatments beginning with chlorine (C), alkali (El), chlorine dioxide (DI), alkali (E2) and ending with chlorine dioxide (D2). Spent chlorination liquor or acidic liquor results from the f i r s t stage, CI, while the remaining stages produce an alkali liquor. Depending on the mill these effluents may be sewered separately or together. A water wash follows each stage. A hypochlorite stage (H) may be inserted between the El and DI stages. In the C stage elemental chlorine is added at 60-70 kg/tonne pulp at 27 15-30°C resulting in a pH 1.5-2.0 (Kringstad and Lindstrom, 1984). Then at 70°C and a pH 11 during the f i r s t alkali stage, El, a sodium hydroxide 55-solution is added to the chlorinated pulp at 35-40 kg/tonne (Kringstad and Lindstrom, 1984). The chlorine treatment promotes lignin degradation while the alkaline extraction neutralizes acids formed during chlorination and dissolves some of the degradation products. The remaining bleaching stages remove less organic material and produce less toxicity than the f i r s t two bleaching stages (McKean, 1980). The DI, E2, and D2 stages conclude the bleaching sequence to achieve maximum brightness and purity. The final stages of production include screening, pressing, cutting and packaging the product for market. 4.3 WASTE MANAGEMENT SYSTEMS 4.3.1 FORMATION OF PULP FIBER WASTE Counterf low washing minimizes waste water and concentrates dissolved substances. Acid waste is handled separately while waste from the brown stock and any later bleaching stages i s directed to the mill's main sewer (Figures 4.2 and 4.3). Black liquor or i t s condensates normally do not enter the raw waste sewer. Solid wastes are directed to a large settling pond which i s the primary clarifier. Solid waste at the Prince George mill also includes waste from a nearby paper mill. Inorganic and organic additives added in the processing of the paper may be present in this waste and may increase the toxicity of the raw waste (McKean, 1980). Collected solid material thickens in a second smaller clarifier. Water is squeezed from the slurry. Depending on the type of press, the end-product, pulp fiber waste (PFW), ranges from 64.8 -84.4% moisture (Croy and Rode, 1988). The PFW i s stockpiled and burned 28 cc UJ CO • co < cr UJ UJ CO z UJ 0 cc UJ UJ CO Figure 4.2 Flowchart of the solid waste disposal route at Weyerhaeuser Canada Ltd., Kamloops, B.C. 29 CHEM U DRAIN SPILL LAGOON BLEACH PLANT -} C STAGE | E1 S T A G E | h l HBER RECOVERY" PGP&P SLUDGE CLARIFIER SLUDGE DEWATER1NG STORAGE \ T O AERATION STABILIZATION A T PRINCE GEORGE P&P I T O RIVER Figure 4.3 Flowchart of the waste disposal system at Canfor Ltd., Prince George, B.C. 30 within the mill to generate steam or used as lan d f i l l . The pulp fiber waste (PFW) i s a combination of the spillage and overflow from the kraft process, rejects from the brownstock and bleaching sequence, and rejected fiber due to dirt, wood dirt or color. The amount of this solid waste is approximately 1% of the total production of pulp (J. Zagar, personal ccmmunication). 4.3.2 DETOXIFICATION KRAFT PULP MILL WASTE AND EFFLUENTS Detoxification mechanisms in the pulp and paper industry include biological and physiochemical treatments. Toxic, wood-derived compounds are variable in their biodegradability. Certain chemical wastes and byproducts are unstable and may be detoxified by one or a combination of the following conditions: pH control, lime precipitation, foam fractionation, activated carbon treatment, aeration, ultrafiltration, reverse osmosis, or primary clarification (Leach et al . , 1978b). Monitoring and buffering of the pH provide an essential reduction in the toxicity of the outgoing effluents (Leach et a l . , 1978a; McKean, 1980). Kraft chlorination effluents were less toxic at pH 7-9 than at more acidic pHs (Mueller et al . , 1977; Walden and Howard, 1981). The mutagenicity of chlorinated bleach effluents decreased by adjusting the pH to 10 or greater (Leach, 1980). The pH of a solution has no effect on the rate of resin acid degradation (Hemingway and Greaves, 1973). Volatile reduced sulfur compounds are believed to be stripped by aeration (Leach et al . , 1978b). Other non-volatile toxicants such as palustric acid, epoxystearic acid and unsaturated fatty acids are not stable in aqueous solutions even under mild conditions of aeration and are unlikely to survive microbiological oxidation (Leach et al . , 1978b). 31 Aerated lagoons (5 day retention period) and extended air-activated sludge systems (8-16 hr retention period) remove 80-100% of the fatty and resin acids, and bleach toxicants from kraft and sulfite mill effluents as determined by difference before and after biological treatment (Easty et al. , 1978). However, these removal rates may be misleading since 100% removal was assumed i f the concentration of the compound in the final effluent was below detection limits of the analysis. Normally, resin and fatty acids are removed with a 90% or greater efficiency except during shock loads (McKean, 1980). Resin acids are readily broken down in the biotreatment systems or by the flora in the receiving waters (Hemingway and Greaves, 1973). However, chlorinated analogs are less removable and more difficult to decompose than naturally occurring wood extractives (Easty et al., 1978; Mueller et al . , 1977; Walden and Howard, 19.81; Leach et al., 1977, 1978b). The decrease in chlorinated phenols ranged between 0-40% of the original total when exposed to microbiological treatment in aerated lagoons (Oikari and Holmbom, 1986). Chlorinated resin acids such as cUctilorodehydroabietic acid and tri<^oroguaiacol are poorly biodegradable (Leach et al . , 1977, 1978b). Biodegradability decreased with increasing chlorine substitutions (Lee et al. , 1978a). Biological treatment detoxified unsaturated fatty acids > resin acids > chlorinated resin acids > chlorinated guaiacols (Chung et al., 1979). In declining order the relative biodegradabilities of the following chlorinated organic compounds are: dehydroabietic acid > pimaric acid > tetrachloroguaiacol (after microbial adaptation) > pimarol > monochlorodehvdroabietic acid > dichlorodehydroabietic acid > trichloroguaiacol (Mueller et al., 1977; Lee et al . , 1978a). When'the chlorinated phenols are biodegradable, depending on the treatment 32 conditions, the rate i s slow (Kringstad and Tiindstrom, 1984). Chlorinated phenols, chlorinated guaiacols and various chlorinated resin acids have been detected in the receiving waters of the treated mill's discharged into the effluents (Kringstad and Lindstrom, 1984). Any chlorinated organic receiving waters thus may persist in the environment (Walden and Howard, 1981). The treatment systems previously discussed apply to the effluent emissions alone. Primary clarification alone has l i t t l e effect on the raw waste toxicity (McKean, 1980). Thus, any chemical contamination from the process in the PFW is not likely to be affected by the clarifier. It i s possible that i f chemical contamination exists in either the pulp products or liquid discharges from the processing system, then the associated PFW likely i s conteminated. Although the need for chemical characterization of PFW from different sites has been emphasized (Croy and Rode, 1988; Baker et al. , 1975), no specific hazardous chemicals in PFWs have been reported. CHAPTER FIVE 33 5.0 TOXICANTS IN THE EFFLUENT AND SOLID STREAMS OF KRAFT MILLS Pulp and paper effluents are a complex mixture of dissolved lignin, cellulose degradation products and wood extractives (Nestmann et al. , 1980). If toxicants can be identified in the pulp mill effluent, because of the high moisture content of PFW, likely similar compounds will be present in the PFW. Over the past fifteen years much effort has been directed toward isolating and identifying the chemical contaminants and toxicants in pulp and paper effluents. Identifiable toxic compounds in effluents include resin acids, chlorinated resin acids, unsaturated fatty acids and chlorinated phenols (Mueller et al. , 1977). The concentration and type of these substances varied depending on: 1) the pulping process (kraft, sulfite, mechanical or senu.-mecharri.cal), 2) the process streams with the mill (unbleached white water, acid sewer, caustic sewer, general sewer, or cla r i f i e r influent), 3) the wood source, 4) disruptions in the system, and 5) a number of unidentified factors (Walden and Howard, 1977; McKean, 1980). Naturally occurring compounds such as resin acids, chemical contaminants, and compounds formed during the bleaching process have been identified as the major pollutants in the untreated acid effluent sewer waste from kraft pulp mills (McKean, 1980). The distribution of total raw waste toxicity in pulp mills was: 40% from the f i r s t caustic (El) filtrate; 30% from the kraft pulp recovery-related operations; 15% from the chlorine (C) stage filtrate; 5% from the other remaining bleach stages; and 10% from the paper mill and other sources (McKean, 1980). Approximately one tonne of bleached softwood pulp produces 4 kg of organically bound chlorine (Kringstad and Lirxistrom, 1984). Each day 34 Canadian pulps produce an estimated 30,000-100,000 kg of chlorinated hydrocarbons from the bleaching of pulp (Kroesa, personal communication). The bleaching liquors dissolve 5%, 1.9% and 1% of any reitaining lignin, polysaccharides and extractives respectively from the "pulp" that enters the bleaching (Kringstad and Lindstrom, 1984). Seventy-five percent of the material which is dissolved after digestion occurs during the f i r s t two bleaching stages (C and El) of the bleaching process (Kringstad and Lindstrom, 1984). 5.1 VOLATILE COMPOUNDS Hydrogen sulfide, methyl mercaptan, methyl sulfide and dimethyl sulfide found primarily in the recovery area waste (ie. black liquor) (Walden and Howard, 1977; McKean, 1980; Mueller et al. , 1977) were volatile toxic constituents in kraft effluent. Predominate volatile neutral chlorinated compounds in the acidic and alkaline spent liquors include chlorinated acetones, 1,1-dicMoramethylsulfone, chloroform and dichloromethane. 5.2 CAUSTIC EXTRACTION PRODUCTS Effluent from the f i r s t caustic (El) stage followed by the chlorine (C) stage were the most toxic of the effluents derived from the bleaching sequence (McKean, 1980). Alkali treatment in the E l stage ionized any previously formed acidic groups and caused a loss of organically bound chlorine (Kringstad and Lindstrom, 1984). Mono- and dicMorodehydroabietic acid, 9,10-epoxystearic acid, 3,4,5-trichloroguaiacol, 4,5-dichloroguaiacol, and 3,4,5,6-tetrachloroguaiacol contributed to the toxicity of the kraft caustic extraction effluent (Leach and Thakore, 1975, 1976; Walden and Howard, 1977; Mueller et al. , 1977; McKague, 1981a, 1981b). The amount of chlorinated guaiacols in the caustic 35 extraction effluent was related to the kappa number of the brown stock (measurement of the lignin content of the unbleached pulp) and amount of chlorine applied (Leach and Thakore, 1975). Of the chlorinated catechols and chlorinated guaiacols produced from the chlorination of the lignin, tetrachloroguaiacol was the most toxic (McKean, 1980). 5.3 ACIDIC COMPOUNDS Acidic compounds identified in the pulp mill effluents included fatty, hydroxy, dibasic, aromatic and resin acids. The higher fatty acids and resin acids were found in the unbleached white water from kraft pulping of the wood chips. Resin acid soaps accounted for 82% of this toxicity when Douglas f i r and western hemlock was pulped (Leach and Thakore, 1974a). Formic and acetic acids were quantitatively the most important fatty acids in the total mill effluent (Kringstad and Lirx3strom, 1984). Glyceric acid and other hydroxy acids resulted from oxidized carbohydrates (Kringstad and Lindstrom, 1984). Abundant dibasic acids derived from residual lignified carbohydrates included oxalic, malonic, succinic and malic acids. These acids were found in both the acidic and caustic spent liquor (Kringstad and Lindstrom, 1984). 5.3.1 RESIN ACIDS About 80% of the toxicity of the total mill effluent is attributed to the resin acids (Figure 2.3) (McKean, 1980). Pimaric-type resin acid soaps tended to be more toxic than abietic-type soaps (Leach and Thakore, 1974a; 1974b). The brown stock wash from kraft pulping of pine wood contained resin acid salts as high as 100-400 ppm (Heiruixjway and Greaves, 1973). Yet resin acids insects and animals (Hemingway and Greaves, 1973; McKean, 1980). and resin acid salts from 1 to 5 ppm can be hazardous to fish, and aquatic 36 The resin and fatty acids which were not removed in earlier washings in the process may be chlorinated, and may form mono- and dic±ilorodehydroabietic acid, epoxy stearic and dichlorostearic acid in the bleaching stages (Leach and Thakore, 1975 and 1976; McKean, 1980). The presence of resin acids was spectulated to cause embryonic resorptions in mice ingesting hexane extracts of Pinus ponderosa needles (Chung et al . , 1979). Reproductive disorders in cattle including weak or stillborn calves, retained placenta, maternal toxicity and maternal death have been associated with the ingestion of Pinus ponderosa needles (Kubik and Jackson, 1981). However, whether the effects were due to the synergistic affect of the resin acids or to the particular concentrated mixture of resin acids was unknown (Kubik and Jackson, 1981). 5 . 4 CHLORINATED ORGANICS Chlorine, either as the molecular species or as a radical, reacts with organic matter. As a radical, chlorine may react with the carbohydrate fraction of the wood while molecular chlorine reacts with residual lignin (Kringstad and Tiindstrcm, 1984). Lignin, depolymerized by the chlorine and hydrogen chloride, dissolved in the chlorination liquor. Wood species, lignin content of the unbleached pulp (kappa no.), amount of chlorine applied, chlorine temperature, pulp washing efficiency and water recycling practices influenced the generation of chlorinated organics (Leach, 1980). Lignin degradation in the kraft bleach process also resulted in chlorinated and non-chlorinated monomeric phenols (McKague, 1981a). A variety of chlorinated organic materials existed in the effluent although many compounds which were present were unidentified. Of chlorinated organic cxaxpounds with a molecular weight less than 1000, 30% were found in the 37 spent chlorination liquor and 5% of these compounds were found in the spent alkali extraction (Kringstad and Lindstrom, 1984). Higher molecular weight chlorinated organics which were not completely characterized, were believed to be biologically inactive (Kringstad and Lindstrom, 1984). Whether or not these compounds can be further broken down to biologically and chemically active substances i s unknown (Kringstad and Lindstrom, 1984). Chlorinated residual lignin produced chlorinated phenols, chlorinated vanillins, catechols, and chlorinated guaiacols (Figure 2.3). A l l were identifiable in the spent liquors (Kringstad and IirKtetrom, 1984; McKean 1980). The acidic spent liquor from the f i r s t chlorination stage contained a high proportion of toxic organochlorides including t r i - and tetrachlorccatechol, 2,6-cUchlorohydroquinone and a group of poly-ctLlorodihydroxybenzenes (Walden and Howard, 1981; McKague, 1981b). Most chlorinated guaiacols and vanillins were found in the spent alkali extraction (Kringstad and Lirdstrom, 1984). 5.4.1 DIOXINS AND FURANS 5.4.1.1 STRUCTURE Dioxin, polychlorinated dibenzoparadioxin or PCDD, is a hydrocarbon molecule consisting of two benzene rings joined by an oxygen bridge (Figure 5.1a). One or more chlorine molecules may be attached to any of eight possible positions. Furan, polychlorinated dibenzofuran or PCDF, similar in chemical and physical properties to PCDD, have one less oxygen between the two benzene rings (Figure 5.1b). Any one of the 210 isomers in the dioxin-furan family i s commonly referred to as "dioxin". Only a few of the 75 different PCDDs and 135 different PCDFs have been extensively studied to determine their chemical and physical properties (McConnell and Moore, 1978; Stalling et al . , 1982). 38 The most toxic dioxin known i s 2,3,7,8-tetracMorooUberizoparadioxin (2,3,7,8-TCDD) (Nygren et al., 1986) which is often used as the prototype for a large group of halogenated aromatic hydrocarbons (Al-Bayati et al . , 1987). 5.4.1.2 DIOXTNS AND THE PULP AND PAPER INDUSTRY Dioxins may be formed during the bleaching sequence, or in unbleached pulp may come from contaminated chemical treated wood. In 1985 American studies found dioxins in the sludges of kraft pulp mills in Wisconsin, Maine and Minnesota (Van Strum and Merrell, 1987; Kroesa, personal communication). In 1988, Weyerhaueser Canada confirmed dioxin contamination in their primary cla r i f i e r sludge and in their final paper products (Zagar, personal communication). Dioxin contaminated fish and crabs have been found downstream from kraft mills (Van Strum and Merrell, 1987). Recent press releases also cited dioxin contamination in crabs, fish and birds 7 eggs near Canadian mills. Between 7 and 13 ppt TCDD was been found in finished paper products such as paper towels and writing paper (Gray, 1987). The highest dioxin levels were associated with kraft mills using chlorine bleaching (Van Strum and Merrell, 1987). In December 1984, Maine kraft mills voluntarily halted the application of pulp and paper sludges to their own land and to acjricultural acreage. Dioxins are well known contaminants of polychlorinated byphenyls (PCBs). Belyea et a l . (1979) have reported PCB contamination as well as a wide range of organic chemical contaminants in solid cellulosic waste from the St. Louis solid waste stream. PCB levels were estimated to be 0.5 ppm (Belyea et al . , 1979). Farr et al . (1974) reported PCB concentrations in brown cardboard (0.047 ppm), newspaper (0.120 ppm), computer paper (0.320 ppm), and grey cardboard (0.610 ppm). Since PCB levels were very lew in paper 39 products, likely any contamination from dioxins would be present at extremely low levels. a) CI b) Figure 5.1 The structural formulae of (a) polychlorinated clibenzodioxins and (b) polychlorinated dibenzofurans where x and y refer to the number of attached chlorine molecules. 5.4.1.3 PROPERTIES The threat of dioxins stems from their resistance to breakdown, their potential for bioaccumulation, and their biological activity (McConnell and Moore, 1978; Hague et al. , 1977; Kenaga, 1980; Matsumura, 1977). Dioxins are hydrophobic and lipophilic. In water 2,3,7,8-TCDD is soluble at 200 ppt. As well 2,3,7,8-TCDD is highly volatile (2.02 xlO" 4 Pa at 25°C) (Freeman and Schroy, 1985; Schrcy et al., 1985) so aerosols are easily created (Cattabeni et al., 1978). Dioxins melt at 302°C (Cattabeni et al., 1978) but are not thermally degraded below 800°C (Cattabeni et al. , 1978; Liberti and Brocco, 1982). Under normal conditions, dioxins resist photochemical, biological, chemical and bacterial degradation (Cattabeni et al., 1978; Schroy et al., 1985). Dioxins are poorly excreted once absorbed by living organisms (Nygren et al., 1986) and accumulate in the body, concentrating in the fatty tissues (Bickel and Muhlebach, 1982). The half-life of 2,3,7,8-TCDD was 58 days in 40 juvenile rainbow trout and 109-317 days in echo salmon (Muir et al. , 1985). In small rodents the half-life of 2,3,7,8-TCDD was 10-43 days while in the female rhesus monkey the half-life was about 1 year (Nygren et al. , 1986). In animals 2,3,7,8-TCDD is a toxicant, mutagen, carcinogen and teratogen (Al-Bayati et al. , 1987; Cattabeni et al., 1978; Nygren et al. , 1986; Van den Berg et al., 1986; Whitlock, 1987). Laboratory animals exposed to 2,3,7,8-TCDD suffered from a variety of general symptoms including: loss of weight, skin disorders, a suppressed immune system, impaired liver function, altered blood function and l i p i d metabolism, impaired reproduction including birth defects, and an increase in tumors (CCREM, 1987). The only specific human health sign associated with dioxin exposure is chloroacne (Cattabeni et a l . , 1978). The toxicity of a particular dioxin varies with the position and number of chlorine molecules (McConnell and Moore, 1978; Whitlock, 1987; Parker et al., 1980). The sensitivity to dioxin exposure varies with the animal species, the potency of the particular dioxin isomer, the exposure level, the age and sex of the individual and many other undefined factors (Whitlock, 1987; Cattabeni et al. , 1978). The World Health Organization suggested that man probably is less sensitive to PCDDs and PCDFs than other mammals (Nygren et al., 1986). 5.4.1.4 DIOXINS AND CATTLE Much of the dioxin research in cattle originated because of pentachlorophenol (PCP) contamination problems in bedding ingested by cattle. Dioxins and furans are contaminants of PCP (Parker, 1980). Where mature Holstein cows were fed 0.2 mg PCP/kg BW for 75 days and 2.0 mg PCP/kg BW for 60 days, octa-, hepta- and hexachlorodibenzodioxins (OCDD, HpCDD, HCDD respectively) was present in liver and muscle tissue (Zabik and Zabik, 41 1980). The liver acxnjmulated higher levels of a l l isomers ranging up to 183 ppb of OCDD in the wet tissue (Zabik and Zabik, 1980). In 1979-1984 in the USA, in a survey of various foods of animal origin were collected and were measured for dioxin contamination. Low levels (< 300 ppt) of OCDD and HpCDD in bacon, chicken and porkchops were identified. Beef livers contained up to 3830 ppt OCDD and 428 ppt of HpCDD (Firestone et al. , 1986). Abortions and stillbirths in cattle associated with dioxin poisoning were implicated in the spraying of the dioxin contaminated herbicide 2,4,5-trichloroacetic acid (2,4,5-T). Adult cattle, seemingly healthy, had focal skin lesions, patchy depigmentation and hair loss (Davies et al . , 1985). The US Environmental Protection Agency (EPA) found dioxins in beef fat of cattle grazing on rangeland sprayed with 2,4,5-T (Westing, 1978). Postnatal mortality in mouse pups fed TCDD contaminated milk increased but surviving animals exhibited no signs of abnormal development (Nau et al. , 1986). Postnatal weight gain in surviving mice was within the range of the controls or slightly higher (Nau et al . , 1986). Milk production, body weight, or feed consumption were not affected when Holstein dairy cows were fed rations containing 0.5 ppm 2,3,7,8-TCDD (Jensen and Hummel, 1982). Lack of visual signs in cases of dioxin poisoning i s not unusual. 5.5 TOXICITY AND MUTAGENICITY A dose response curve assumes that the higher the concentration, the shorter the exposure time required to produce a specific effect. Where survival i s the measured parameter, i f the concentration exceeds the lethal threshold, death results. The concentration which k i l l s 50% of a test population is the LC50 value. LC50 value for various compounds found in pulp mill effluents are listed in Table 5.1. Resin acids, chlorinated resin 42 acids and chlorinated guaiacols show values less than 1.0. The smaller LC50 values corresponded to greater relative toxicities. Acute toxicity in pulp mill effluents is cxammonly measured with fish bioassays where the fish (rainbow trout, stickleback, and chum salmon) are subjected to a known concentration for 96 hours (Van Aggelen, personal ccOTttunication). The most stringent provincial zoning requires that 100% of the fish survive for 96 hr in a 100% v/v effluent concentration for freshwater mills, and that 30% survive in 100% v/v in coastal mill effluents (Braybook, personal cximniunication). The 96 hr LC50 values for untreated neutralized bleach kraft effluents ranged from 15-50% v/v (Walden and Howard, 1981). Chronic toxicity i s rarely tested in effluents unless there is a noticeable problem in the receiving waters. At times the biological oxygen demand (BOD) can be correlated to toxicity. Although toxicity can be correlated to oxygen depletion in the water, the inverse i s not true. Under conditions of sufficiently high oxygen levels, toxicity may s t i l l result. Pulp and paper effluents can induce genetic effects in test organisms (Nestmann and Lee, 1985; Douglas and Nestmann, 1980). Bleached kraft effluents affected fish by interfering with the transfer of oxygen across the g i l l membranes, increasing the g i l l cleansing reflex frequency, affecting ventilatory water flow at the g i l l s and oxygen uptake, and 43 Table 5.1 The relative toxicity of identified substances in kraft pulp and paper wastes as indicated by the lethal concentration value (LC50) (adapted from Leach and Thakore, 1974b). COMPOUND 96-HR LC 5 0 (% by volume) RESIN ACIDS AB1ET1C 0.7 DEHYDROAB1ETIC 1.1 ISOPIMARIC 0.4 PALUSTRIC 0.5 PIMARIC 0.8 CHLORINATED RESIN ACIDS M0NOCHIOR0DEHYDR0AB1ET1C ACID 0.6 DICHL0R0DEHYDRAB1LT1C ACID 0.6 CHLORINATED PHENOLICS TRICHDDRGUAIACOL 0.72 TETRACHDDROGUAIACOL 0.32 VOIATILES HYDROGEN SULFIDE 0.3-0. 7 METHYL MERCAPTAN 0.5-0. 9 SODIUM SULFIDE 1.0-1. 8 SODIUM HYDROXIDE 10-27 SODIUM CARBONATE 33-58 CHLORINATED CATACOLS TETRACHLOROCATECOL 0.8 DICHLOROCATECOL 2.9 changing breathing patterns and arterial oxygen tension (Walden and Howard, 1977, 1981). Sublethal concentrations reduced maximum swimnung speed and changed plasma glucose concentrations, blood c e l l count, liver glycogen and muscle glucose (Walden and Howard, 1977, 1981). Deformities also occurred in oyster embryos (Walden and Howard, 1981). The undiluted kraft chlorination effluent i s toxic. The median lethal time (LT50) (amount of time 50% of a test population dies in a known concentration of a particular compound) of juvenile rainbow trout in undiluted kraft chlorination effluent ranged from 1.2-9 hours (Leach et al., 1978b). 44 Several mutagenic cxxrrpounds in spent chlorinated liquor were identified by the Samonella/mammalian-microsome test (Table 5.2) (Kringstad and Lindstrom, 1984). Although the spent chlorinated liquor was less toxic (Leach and Thakore, 1975) than the caustic liquor, the former was produced Table 5.2 Mutagenic compounds in the spent chlorination liquor identified with three strains of Salmonella typhimurium by the Salironella/mammalian-microsame test (taken from Kringstad and Lirxistrom, 1984). STRAIN OF COMPOUND SALMONELLA TYPHIMURIUM DICHDDRDMETHANE TA 100 EROMODICHDDROMETHANE TA 100 DIBROMOCHLORGMETHANE TA 100 TRICHLOROETHANE TA 100 TETRACHLOROETHANE TA 100 TETRACHLOROPROPENE TA 98 TA 100 TA 1535 PENTACHLOROPROPENE TA 100 TA 1535 1,3-DICHTJDROACETONE TA 100 TA 1535 1,1,3 -TRICHLOP£)ACTETONE TA 100 1,1,3,3 -TETRACHLOROACETONE TA 100 PENTACHLOROACETONE TA 100 HEXACHDDROACETONE TA 100 CHLOROACETALDEHYDE TA 100 TA 1535 2-CHLOROPROPENAL TA 100 TA 1535 3 -CHLORO-4 -DICHDDPX>METHYL- TA 100 5-HYDROXY-2(5H)-FURANONE in larger quantities than the latter. Thus the associated toxicity of the spent chlorinated liquor was much greater (Kringstad and Lindstrom, 1984). Other microbial (Nestmann and Lee, 1985) and mammalian in vitro assays including the Salmonella/mammalian-microsome test (McKague et al. , 1981; Nestmann et al. , 1980, 1979; Nestmann and Lee, 1981) have shown mutagenic activity in pulp mill effluent. Black liquor and first-chlorination stage effluent showed high mutagenic activity (McKague et al. , 1981b; Nestmann et al. , 1980, Douglas and Nestmann, 1980). The caustic extraction stage showed no mutagenic activity (Douglas and Nestmann, 1980). Partial characterization showed the mutagenic material in the chlorinated effluent to have a molecular mass less than 1000 (Douglas et al . , 1981). 45 Aside from those compounds listed in Table 5.2, other chemicals found in pulp and paper effluents mutagenic in Salmonella typhimurium were: 1,2-dichloroethane, benzyl chloride (McKague et al . , 1981), bromo-p-cymene, dacMoro-p-cymene, and neobietic acid (Nestmann et al., 1980). Yeast assays showed neobietic acid, tetrachloropropene and pentachloropropene, dichlorocatechol, dichloroguaiacol, chloro-cis-muconic acid, 7-reversions in oxcdehydroabietic acid and acetovanillone were mutagenic and caused strain XVT85-14C of Sacx±iaramyces cerevisiae (Nestmann et al., 1985). Both the chlorination and alkali liquors contained low concentrations of carcinogens such as chloroform, safrole and carbon tetrachloride (Lee et al. , 1978), and suspected carcinogens including various chlorinated benzenes and phenols, epoxystearic acid and dichloromethane (Lee et al . , 1978; Kringstad and Lindstrom, 1984). The biological risk of the exposure to these effluents is dif f i c u l t to assess because of the lack of animal carcinogenicity data. The above discussion illustrates the point that a large number of chemical contaminants and toxicants exist in raw pulp mill effluent. Since these compounds are formed at various immediate processing stages, i t is possible that the final product (pulp) as well as other byproducts (PFW) may also contain similar compounds. Whereas containinants in the pulp and the solid waste (PFW) have the chance to be partially "washed out" during processing, these same compounds are concentrated by the system in the effluent. However, PFW has a large moisture content which may contain compounds similar to those identified in the effluent. This discussion is then a bridge to begin the search to identify possible chemical contaminants in PFW. EXPERIMENTAL SECTION CHAPTER SIX 47 6.0 OBJECTIVES This study investigated the suitability of pulp mill fiber waste (PFW) as a feedstuff for beef cattle based on the results of a survey of PFWs from ten different pulp mills in British Columbia (Croy and Rode, 1985). Because of the high fiber and low mineral content, high in sacco digestibilities of the PFWs, and the suitability of the geographic locations of the pulp mills in relation to cattle production, PFWs from Prince George Pulp and Paper, Canfor Ltd., Prince George, B.C. (PG PFW) and Weyerhaeuser Canada Ltd., Kamloops, B.C. (K PFW) were chosen for further investigation. The main objectives of this study was to examine the nutritional, safety and practical aspects of feeding PFW to ruminants. The comparisons of PFW sources, and the treatments of various PFW silages which are discussed within the scope of this thesis are subordinate to the main objective. The secondary objectives are listed below. 1. To investigate ensiling PFW as a preservative and storage technique. 2. To evaluate the effect of surplus whey as a silage additive in ensiled PFW mixtures. 3. To measure the digestibility coefficients of the PFW silages in vivo using sheep and cattle. 4. To assess the palatability of PFW silage by measuring the voluntary intakes of sheep and dairy heifers. 5. To assess animal performance by measuring weight gain, intake and feed conversions of beef cattle which were fed PFW silage. 48 6. To identify and to quantify chemical contaminants in the PFW, and to discuss the toxicological implications of feeding PFW to meat producing animals. 7. To present recommendations on the feeding and handling of PFW under feedlot conditions, including an economic evaluation. In the course of meeting the above objectives, the following laboratory techniques were assessed: 8. To determine the appropriateness of acid insoluble ash as an internal marker to measure digestibility of PFW silages. 9. To compare extraction methods of volatile fatty acids from PFWs by steam distillation versus direct injection via a Sep-pac f i l t e r onto a gas chromatograph. C H A P T E R S E V E N 49 7 . 0 A P R E L I M I N A R Y S U R V E Y O N T H E E F F E C T O F E N S I L I N G P U L P F I B E R W A S T E W I T H V A R I O U S A D D I T I V E S : T H E C H E M I C A L C O M P O S I T I O N O F P U L P F I B E R W A S T E S I L A G E A N D I T S E F F L U E N T 7 . 1 I N T R O D U C T I O N At pulp mill sites, storage of fresh pulp chips and residues in large piles for use as a fuel has posed problems in the past because of decomposition and spontaneous combustion (Springer et al., 1978). A number of variables affect the storage of pulp chips and pulp residues including geographic area, wood species, time of year and particle size of materials in the pile (NRC, 1983). Thus, the NRC (1983) advised fresh wood waste intended for livestock feed not be stored in piles for extended periods of time, nor covered with plastic, canvas or heavy snow because of the probability of the materials trapping heat and causing rapid internal heating. However, low uncovered piles which were well ventilated maintained low internal temperatures (NRC, 1983). Despite the high moisture content, Croy and Rode (1988) reported no signs of deterioration in PFWs piles when stored under aerobic conditions for more than 30 days. Lemieux and Wilson (1979) reported high moisture contents PFWs and rations contairiing more than 40% PFW, froze during the winter when stored outside . The high moisture content and bulk of the pulp mill fiber wastes must be considered i f PFW is to be used as an on-farm animal feed. In this experiment, ensiling was examined as a possible low cost preservation and storage technique. PFWs from two different British Columbia pulp mills were combined with various additives and ensiled. These PFW silages were assessed as ruminant feeds on the basis of chemical composition. 50 7.2 MATERIALS AND METHODS In the f a l l of 1985, K PFW and PG PFW were obtained. These two PFWs were ensiled with five different additives. Duplicated silos containing PFW from each of the two kraft pulp mills and ensiled without any additives, acted as controls. The remaining silage mixtures consisted of PFW, barley or hay, liquid cottage cheese whey or water, and urea in the proportions outlined in Table 7.1. Water was added to increase the moisture content of K PFW. Permatubes (Permaform c cardboard construction and industrial cylinder tubes) (height: 0.91 m, diameter: 0.41 m) lined with polyethylene plastic and placed on wooden palettes served as silos. Each silo contained 34 kg of wet material. A 22 kg weight was placed on the top of each silo. Silos were arranged randomly in two groups in a barn at the Prince George Research Station. The two silo groups were wrapped in one-inch f o i l backed insulation. A length of plastic tubing at the bottom of each silo allowed effluent to be collected. A temperature probe was centered in each silo. Room and silage temperatures were recorded twice daily. After a 70 day ensilage period, the silos were opened. Silage was sampled from the top and bottom of each silo, and analyzed for dry matter (DM), ash, pH, crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF) and water soluble carbohydrate (SCHO) content. Silage samples were composited for each silo and analyzed for volatile fatty acids (VFAs). Total effluent from each silo was weighed, and analyzed for DM, ash, pH, CP and VFAs. Dry matter was determined by weight difference of samples dried in a force-air oven at 48° C for 48 hr, and corrected for VFA losses. Inorganic material was determined according to the dry ash method of Chapman and Pratt (1961). The pH of liquid samples was measured <±Lrectly. The pH of solid 51 samples was measured acxording to the Analysis of Agricultural Materials (1973) adjusting the sample:water ratio to 1 g: 75 ml. Nitrogen and CP were determined using the Macro Kjeldahl Method acxxirtiing to the Official Methods of the AOAC (1975). ADF and NDF were measured acxording to the method of Waldern (1971). Hemicellulose was calculated by the difference of NDF and ADF. Water soluble carbohydrates were determined by the methods outlined in the Analysis of Agricultural Materials (1973). Acid detergent lignin in the PFW samples was determined according to Van Soest (1963)i» Table 7.1 Proportions of ingredients on a dry matter basis of the pulp fiber waste silages INGREDIENTS PGBW2 PGHW PGB TREATMENTS PGH KBW KHW KB KH PG PFW1 69.023 70.08 71.11 72.23 - - - -K PFW1 - - - - 81.13 81.88 82.60 83.38 BARLEY 26.67 - 27.47 - 16.25 - 16.54 -HAY - • 25.54 - 26.33 - 15.47 - 15.75 WHEY 2.93 2.97 - - 1.80 1.80 - -UREA 1.38 1.40 1.42 1.44 0.84 0.85 0.86 0.86 1 - PG PFW = Prince George pulp fiber waste; K PFW = Kamloops pulp fiber waste 2 - B = barley; H = hay; BW = barley-whey; HW = hay-whey 3 - a l l values are expressed on a dry matter basis as percentages of the total 1 - After chemical pulping treatment, acid soluble lignin in semi-bleached pulps may be more than half the total lignin content. The acidic conditions from the kraft digestion process predispose the remaining lignin in pulp or PFW to digestion with sulfuric acid as used in the determination of lignin by Van Soest's method. This latter method may underestimate the actual lignin content in PFW. Total lignin content in pulp can be determined by indirect methods based on the chlorination of lignin or the oxidation of the lignin based on the kappa number of the pulp. Lignin in PFW would be better determined according to the methods outlined in TAPPI (1974) "Acid-insoluble lignin in wood and pulp" T222 OS-74, Atlanta, Georgia. 52 The CORR procedure on the Statistical Analysis System (SAS) (1985) general linear model (GLM) procedure was used to determined Spearman correlation coefficients between chemical analyses of silages and effluents. 7.3.1 RESULTS: SILAGES Table 7.2 shows the i n i t i a l chemical composition of the individual silage ingredients. The PG and K PFW samples were mildly alkaline in pH (8.30, 9.44), high in fiber (NDF = 90.06%, 90.48%; ADF = 83.24%, 84.37%), and low in protein (0.68%, 0.17%), and low in soluble carbohydrates (0.59%, 0.61%). The PG PFW was higher in moisture than the K PFW (DM = 20.08%, 28.81%). The whey also contained a large amount of water (DM = 3.03%). However, on a dry matter basis, whey was a good source of protein (CP = 13.70%) and water soluble carbohydrates (SCHO = 32.63%). The hay and barley served as protein and carbohydrate sources while contributing l i t t l e water. The temperature data for the silages over the 70 day ensilage period is summarized in Table 7.3. During this fermentation period, the silage temperatures never exceeded 33° C nor were they lower than 4° C. The lowest Table 7.2 Chemical composition (on a dry matter basis) of the ingredients in the pulp fiber waste silage mixtures before ensiling INGREDIENTS: %DM2 pH %NDF %ADF %CP %SCHO PG PFW1 20 .08J 8.30 90.06 83. 24 0. 68 0. 59 K PFW1 38 .74 9.44 90.48 84. 37 0. 17 0. 61 WHEY 3 .03 4.56 _4 - 13. 70 32. 63 TIMOTHY HAY 83 .56 - 67.41 33. 31 9. 16 17. 59 BARLEY 88 .57 - 26.46 6. 39 14. 08 4. 13 1 - PG PFW = Prince George pulp fiber waste; K PFW = Kamloops pulp fiber waste 2 - DM = dry matter; CP = crude protein; NDF = neutral detergent fiber; ADF = acid detergent fiber; SCHO = water soluble carbohydrates 3 - values represent the mean of analyses performed in duplicate on single samples 4 - not measured 53 silage tenperatures occurred during the f i r s t four days of ensiling. In most cases, the temperature reached a plateau 15-20 days after ensiling. The PG barley-whey treatment had higher overall minimum, maximum and Day 20 teirperatures (respectively 10.9° C, 32.7° C, and 28.6° C) compared to a l l other treatments. The control silages had consistently lower ininimum, maximum and Day 20 temperatures than a l l the other silage mixtures (PG control: 5.0° C, 27.7° C, 21.3° C; K control: 5.2° C, 27.0° C, 20.4° C). Table 7.3 Minimum, maximum and Day 20 temperatures (degrees C) for pulp fiber waste (PFW) ensiled mixtures TREATMENT MINIMUM MAXIMUM DAY 20 PRINCE GEORGE PFW CONTROL 5.0 (3)1,3 27. .7 (63) 21. 3 BARLEY 6.6 (3) 27. .8 (63) 21. 8 HAY 7.0 (2) 28. .1 (63) 22. 6 BARLEY + WHEY 10.9 (4) 32. .7 (63) 28. 6 HAY + WHEY 5.6 (4) 26. .9 (63) 23. 0 KAMLOOPS PFW CONTROL 5.2 (2) 27, .0 (63) 20. 4 BARLEY" 4.5 (2) 27. .7 (63) 21. 7 HAY 5.9 (1) 28. .9 (63) 22. 9 BARLEY + WHEY 5.7 (4) 27, .7 (63) 23. 2 HAY + WHEY 5.9 (4) 27, .4 (63) 22. 8 ROOM TEMPERATURE 11.4 ± 1.1 (3) 2 30. .0 ± 0.9 (63) 25. 0 ± 0.0 1 - means represent the average daily tenperature of duplicated silos measured twice daily over a 70 day period. 2 - room temperatures are the mean daily temperatures ± standard deviation. 3 - the number in brackets indicates the day on which the specified temperature occurred. Silos were packed on Day 0. The chemical compositions of the silages before and after ensiling is shown in Table 7.4. The final dry matter content of the silages ranged from 19.50% in the PG control to 31.00% in the K control. The PG silages had higher moisture contents than the K silages. 54 Table 7.4 Chemical composition (on a dry matter basis) of pulp fiber waste mixtures before and after ensilage, and the percentage recovery of the original nutritive components. BEFORE AFTER %RECOVERY BEFORE AFTER %RECOVERY treatment: PG CONTROL K CONTROL %DM1 20.082 19.503 97. ,09 28.81 31.00 100 (107.61) %ADF 83.24 81.10 97. ,42 84.37 82.97 98. ,34 %HEMI 6.82 5.47 80.18 6.11 6.57 100 (107.51) %SCHO 0.59 1.79 100 (303.30) 0.61 1.47 100 (240.58) %VFA _ 4 0.03 - - 0.17 -%CP 0.68 1.47 100 (216.11) 0.17 0.20 100 (117.45) %OTHER 8.67 10.14 100 (116.96) 8.74 8.62 98. ,63 PH 6.72 9.22 treatment: PG BARLEY K BARLEY %DM 20.57 22.70 100 (110.34) 25.43 27.51 100 (108.17) %ADF 60.95 66.17 100 (108.57) 70.75 72.63 100 (102.66) %HEMI 10.36 6.95 67.12 8.37 5.82 69. 56 %SCHO 1.55 1.34 86. ,14 1.19 1.30 100 (109.52) %VFA - 10.39 - - 4.87 -%CP 8.49 5.05 59. ,53 4.98 3.47 69. 73 %OTHER 18.65 10.10 54. 16 14.71 11.91 80. 97 pH 5.44 6.65 treatment: PG HAY K HAY %DM 20.25 20.13 99. 42 25.19 26.59 100 (105.55) %ADF 68.89 72.29 100 (104.94) 75.59 73.33 97. 01 %HEMI 13.9 10.57 76. 08 10.47 6.68 63. 78 %SCHO 5.06 1.59 31. 43 3.28 2.10 64. 07 %VFA - 0.62 - - 1.80 — %CP 2.94 4.03 100 (136.91) 1.61 2.92 100 (181.16) %OTHER 9.21 10.90 100 (118.35) 9.05 13.17 100 (145.52) pH 6.49 6.46 treatment: PG BARLEY-WHEY K BARLEY-WHEY %DM 21.19 25.08 100 (118.34) 25.89 27.07 100 (104.57) %ADF 59.16 67.20 100 (113.58) 69.49 71.49 100 (102.88) %HEMI 10.06 8.87 88. 14 8.22 5.49 66. 79 %SCHO 2.46 1.19 48. 41 1.75 1.64 93. 90 %VFA - 8.40 - - 3.34 — %CP 8.65 3.76 43. 52 5.12 4.11 80. 24 %OTHER 19.67 10.58 53. 79 15.42 13.93 90. 34 PH - 5.34 • - - 6.36 -continued. 55 Table 7.4 continued BEFORE AFTER %RECOVERY BEFORE AFTER %RECOVERY treatment: PG HAY-WHEY K HAY-WHEY %DM 20.87 22.38 100 (107.25) 25.65 28.30 100 (110.31) %ADF 66.84 67.37 100 (100.79) 74.51 69.08 92.72 %HEMI 13.49 8.93 66.23 10.28 9.14 88.87 %SCHO 5.88 1.20 20.41 3.81 2.24 58.69 %VFA - 7.70 - - 4.43 -%CP 3.26 3.79 100 (116.36) 1.83 3.35 100 (183.29) %OTHER 10.53 11.01 100 (104.56) 9.57 11.76 100 (122.88) pH 6.02 — mm 6.17 — 1 - BM = dry matter; ADF = acid detergent fiber; HEME = hemicellulose; SCHO = water soluble carbohydrates; VFA = volatile fatty acids; CP = crude protein 2 - "Before" values are based on the composition of the individual ingredients (Table 7.2) in the proportions in which they were used in the silage mixtures (Table 7.1). 3 - "After" values are the mean of duplicated analyses of two samples taken from each duplicated silos; values are expressed on a dry matter basis and corrected for VFA losses during drying. 4 - not measured. 5 - assuming a l l the original component is recovered the value should be 100. The value given in brackets i s the "apparent" recovery. The PG and K control silages had higher ADF values than the treated silages (PG control = 81.10%; K control = 82.97%). The lowest ADF values occurred in PG PFW silages in the barley treatment (66.17%), and in the K PFW silages in the barley-whey treatment (71.49%). The K hay-whey had a higher proportion of SCHO (2.24%) than a l l other silages. The final range in SCHO content in the silages ranged between 1.19%-2.24%. The final hemicellulose content ranged from 5.47% in the PG control to 10.57% in the PG hay, and from 5.49% in the K barley-whey to 9.14% in the K hay-whey silage. Only a small proportion of the silages was crude protein (CP). After ensiling, the PG and K controls had less CP (1.47% and 0.20% respectively) than the treated silages, and the K control had less CP than the PG control. 56 The PG barley had more CP than a l l other silages (CP = 5.05%). The pH of the silage treatments ranged from mildly acidic to neutral pH except for the K control (9.22). The PG barley-whey and PG barley treatments had lower pHs at 5.34 and 5.44 than the other treatments respectively. The "other" fraction consisted mainly of inorganic matter as well as lactic acid, starch, lipids and other unmeasured components. The "before" values showed a range of 8.67% in the K control to 19.67% in the PG barley-whey treatment. In the PG barley and PG barley-whey silages approximately 50% of the original "other" fraction was utilized in the ensiling process. Thus, half of this fraction must have been a readily fermentable component. In the other silages only slight increases or decreases in the original "other" fraction were measurable. Table 7.5 shows individual and total volatile fatty acid concentrations for the PFW silages. The control silages and the hay treatments were low in the individual and combined acids. The PG barley, PG barley-whey and K hay-whey combinations had the highest concentrations of acetic acid, ranging from 2.03-3.55%. The PG barley PFW silage had the highest proportion of propionic acid (1.67%). The control and hay PFW silages also had less butyric acid (less than 0.82%) than the remaining treatment combinations. The PG barley, barley-whey and hay-whey treatments produced 4.46-5.93% butyric acid, while the corresponding K treatments produced 1.74- 2.55% butyric acid. The concentration of isobutyric acid in the PG and K treatments ranged from non-detectable in the controls to 0.18% in the K barley treatment. Isovaleric acid in the PG and K treatments ranged from non-detectable to 0.18%. Less than 0.005% of the dry matter was present as valeric acid. The largest proportion of dry matter in the VFA production 57 crorurred in the PG barley treatments at 10.39%. The PG barley-whey and PG hay-whey PFW silages produced 8.40% and 7.70% of the total dry matter in the form of VFAs. The amount of total VFAs produced by the K treatments ranged from 0.17-4.87% of the total dry matter. The controls and the PG hay treatment a l l produced less than 1% of the total dry matter in the form of VFAS. Table 7.5 Concentrations of volatile fatty acids in pulp mill fiber waste (PFW) silages (percentage of the total dry matter) TREATMENT ACETIC PROPIONIC ISOBUTYRIC BUTYRIC ISOVALERIC VALERIC TOTAL PRINCE GEORGE PFW CONTROL O.OO1 0. OO2 ND3 0.01 ND 0. 00 0. 03 BARLEY 3.55 1. 67 0.10 4.98 0.18 0. 00 10. 39 HAY 0.11 0. 16 0.05 0.12 0.18 0. 00 0. 61 BARLEY-WHEY 2.99 0. 85 0.04 4.46 0.06 0. 00 8. 40 HAY-WHEY 0.93 0. 67 0.10 5.93 0.08 0. 00 7. 70 KAMLOOPS PFW CONTROL 0.01 0. 01 ND 0.06 0.09 0. 00 0. 17 BARLEY 1.80 0. 29 0.11 2.55 0.11 0. 00 4. 87 HAY 0.77 0. 09 0.04 0.82 0.08 0. 00 1. 80 BARLEY-WHEY 1.25 0. 18 0.06 1.74 0.10 0. 00 3. 34 HAY-WHEY 2.03 0. 42 0.05 1.86 0.07 0. 00 4. 44 1 - values represent mean of samples from replicated silos, prepared in duplicate and analyzed in duplicate. 2 - actual value is less than 0.005% of the dry matter. 3 - none detected. 7.3.2 RESULTS: EFFLUENTS Tables 7.6 and 7.7 show the chemical composition of the effluent produced by the PG PFW silages. None of the K PFW silages produced any effluents. Generally the drainage did not start to flow until day 7, and most of this effluent ceased by day 40. Based on observation, the color of the effluent varied with time and treatment. The barley and PFW silages produced a white liquid while those packed with PFW and hay produced a more yellow liquid. Color changes with time tended to be inconsistent. 58 Table 7.6 Chemical composition of Prince George pulp fiber waste silage effluents TREATMENT AMT1 DM ASH2 pH CP2 VFA2'3 (kg) (%) (%) (%) (%) BARLEY 2.024 1.33 31.23 6.51 73.68 0.07 HAY 1.54 1.23 46.40 7.38 73.17 0.07 BARLEY-WHEY 1.70 1.64 33.29 5.65 69.51 0.07 HAY-WHEY 0.81 1.87 46.83 6.48 55.61 0.06 1 - AMT ^ average amount of effluent produced by the duplicated silos; DM = dry matter (corrected for VFAs); CP = crude protein; VFA = volatile fatty acids. 2 - percentage on a dry matter basis. 3 - total percentage of a l l volatile fatty acids measured. Refer to Table 7.7 for individual proportions. 4 - values are the mean of duplicate analyses on duplicate samples from duplicated silos. Table 7.7 Volatile fatty acids in the effluents produced by the Prince George pulp mill fiber waste silage treatments TREATMENT ACETIC PROPIONIC ISOBUTYRIC BUTYRIC ISOVALERIC VALERIC TOTAL BARLEY 128. .171 44. 61 0.36 108. ,64 0.47 1.49 283 .73 HAY 91. .83 34. 46 3.44 55. ,68 0.95 2.28 188 .62 BARLEY-WHEY 99. .71 18. 41 0.00 118. ,96 0.07 1.16 238 .31 HAY-WHEY 56. .67 15. 57 1.51 51. ,67 0.92 1.45 127 .79 1 - values represent mean of duplicated samples, analyzed in duplicate from duplicated silos; values are corrected for the amount of effluent discharged by each silo and expressed as micromoles per gram of the average total effluent produced by each silo. Table 7.6 shows the moisture, ash, protein content and the total volume of effluent. On a dry matter basis, approximately one-third of the effluent was ash and the remaining portion was crude protein with less than 1% as volatile fatty acids. The pH was the lowest in the barley-whey combinations (pH = 5.65) and the highest in the PG hay PFW silage (pH = 7.38). Table 7.7 shows the total concentration of individual volatile fatty acids in etmoles present in the PFW effluents. The PG barley PFW silage emitted more VFAs (283.74 nmoles) in i t s effluent than the remaining treatments. Of the VFAs found in the effluents, acetic and butyric acids 59 tended to contribute the most to the overall total, while isobutyric, isovaleric and valeric acids each contributed less than 5 nmoles to the total. Correlation coefficients between the composition of the PG PFW silage and i t s corresponding effluent are listed in Table 7.8. Only pH, crude protein and total VFA concentrations showed significant positive correlations between silage and effluent. The individual VFAs, silage dry matter and amount of effluent produced, and silage dry matter compared to effluent dry matter failed to show any significant correlations. Table 7.8 Comparisons between the Prince George pulp mill fiber waste silages and the effluents emitted from these silages COMPARISON SILAGE EFFLUENT iT 5 VOLATILE FATTY ACIDS: ACETIC 74.46 ± 62.00 1,2 94.09 ± 33.61 2 0.333 PROPIONIC 26.15 ± 18.37 28.26 ± 13.51 0.286 ISOBUTYRIC 1.84 ± 0.92 1.33 ± 1.53 0.060 BUTYRIC 101.66 ± 84.19 83.73 ± 42.58 0.429 ISOVALERIC 2.65 ± 1.34 0.60 ± 0.49 0.548 VALERIC 20.75 ± 19.54 1.60 ± 0.76 -0.381 TOTAL 227.41 ± 150.00 209.61 ± 80.33 0.714* 6 pH 5.82 ± 0.50 3 6.50 ± 0.68 3 0.881* CRUDE PROTEIN 5.03 ± 1.04 3,4 15.18 ± 5.73 3 ' 4 0.810* DRY MA!1TER(%) 23.60 ± 7.49 1.51 ± 0.31 1 0.571 DRY MATTER (%) IN SILAGE EFFLUENT DISCHARGED 23.60 ± 7.49 3 1.52 ± 0.58 1 -0.095 DRY MATTER (%) IN EFFLUENT AMOUNT OF EFFLUENT 1.51 ± 0.31 1 1.52 ± 0.58 1 -0.643 1 - Values represent the mean ± standard deviation of the duplicated silos from four different treatments which emitted effluents. 2 - Silage values are expressed as micromoles per 1 gram wet silage. Effluent values are expressed as micromoles per total effluent per silo. 3 - Values represent the mean ± standard deviation of two samples taken from duplicated silos analyzed in duplicate. 4 - crude protein for the silage is expressed as percent on a dry matter basis; crude protein for the effluents is expressed in grams per total effluent per silo. 5 - Spearman correlation coefficient. 6 - * denotes a significant correlation between the effluent and silage (P < 0.05). 60 7.4.1 DISCUSSION: SILAGES Chemical analyses of the PFW showed the majority of the PFW to be cellulose (Table 7.2). The pulping process removes most of the other wood components including lignin and protein. The remaining residue was fibrous (NDF = 90.24%, ADF = 83.80%), contained 60-70% moisture, and was mildly alkali in nature (Table 7.2). Before ensiling, the PFW was chopped to avoid large solid clumps of material ensuring uniform mixtures, making PFW easier to compress, and ding air pockets in the silo. Chopping also increased the surface area of the PFW enhancing partial drying prior to ensiling, and increasing surface area for microbial action during ensiling. As well as affecting fermentation quality, the fineness of the ensiled material can also affect intake and the rate of flow through the rumen. The hay or barley in the PFW mixture increased the dry matter of the silage while providing a source of fermentable carbohydrates in which the original PFW was deficient (Table 7.2). Ely (1978) decreased pH and dry matter loss, and increased dry matter, dry matter digestibility and the energy content of grass silage by adding 6, 10, or 19% ground barley. Whey as a silage additive, with i t s acidity and i t s lactic acid content would in theory favor a lactate fermentation. The urea increased the i n i t i a l CP content of the mixture (Table 7.4) and provided a nitrogen source for the bacteria. Urea, when applied to chopped corn, had no effect on the fermentation acids but increased crude protein content (Woolford, 1984). Ureases liberate ammonia which accounts for the preservation properties of urea (Woolford, 1984). cool ambient temperatures at the outset of the t r i a l The i n i t i a l slow increase in silage temperatures partially reflected the (Table 7.3). The maximum silage temperatures corresponded to the day with 61 the highest ambient temperature. Daily silage temperatures reached a plateau around Day 20, and silage temperatures fluctuated between 20-33° C. The addition of barley and whey with the PG PFW promoted the largest temperature increase, above a l l other treatments and controls. The K PFW was considerably drier and did not compact as much as the PG PFW. The moisture retention, the differing compaction properties coupled with the effects of the additives and PFW source may partially account for the temperature differences between treatments, the relatively low silage temperatures and the slow rise in temperature. Higher temperatures and faster heating rates indicate increased microbial activity in the PG barley-whey silage. Energy released by the fermentation of carbohydrates i s responsible for the temperature rise in ensiled herbage (McDonald, 1981). The rate of respiration governs silage temperatures, and silage temperature affects the rate of microbial metabolism (Woolford, 1984). The final silage temperature is dependent on the amount of air present, as well as the insulating properties and specific heat of the herbage mass (McDonald, 1981). The high ADF content of a l l the silages (Table 7.4) reflected the large proportion of ADF in the original PFW (Table 7.2). The amount of ADF in PFW is larger than that found in traditional grains and grasses. The ADF component in the silage consisted mainly of cellulose, lignin and minerals. The variations in the fiber component among the treatments was attributed to the different additives (Table 7.4). Only small proportions of hemicellulose were present in the silages (Table 7.4). The soluble carbohydrate content of the i n i t i a l PFW (PG = 0.59%; K = 0.61%) (Table 7.2) and the final silages (1.20-2.24%) (Table 7.4) was very small. Bolsen (1978) recommended 6-8% SCHO content for ideal silage fermentation conditions. Vetter and Von Glan (1978) recommended 2-3% SCHO content on a 62 wet basis for desirable silages. An adequate SCHO supply as an energy source was essential for the i n i t i a l production of acid by lactic acid bacteria (Vetter and Von Glan, 1978). The silage pHs (Table 7.4) were lower than the original pH of the PFW (Table 7.2). The pH was not lower than 5.34 in any treatment. The slow temperature increase, and the slow i n i t i a l activity by silage microorganisms likely resulted in a slow production of acid. The buffering capacity of the PFW may also affect the final acidity of the PFW silage. In favorable fermentations, the rate of pH decline is more crucial in inhibiting early clostridial growth than the amount of acid produced (Vetter and Von Glan, 1978). The difference in crude protein between the PG and K silages (Table 7.4) was partially due to the i n i t i a l difference in CP content between the two pulp sources (Table 7.2), and the type and level of the additives (Table 1). Generally, a high protein content after ensiling corresponds to increased non-protein nitrogen incorporation into the microbial biomass of the silage. Increased microbial activity corresponds to an increase in acid production and a decrease in the pH of the material. Protein losses, which may affect the overall CP content, may be due to the release of ammonium N, and, in the case of the PG PFW silages, the loss of soluble N and protein in the effluent. When the silos were opened, the controls had no obvious odor other than that of the faint neutral odor associated with pulp mill waste itself. The hay treatments smelled like hay although they were slightly pungent. The hay-whey silages were somewhat "sweeter" while at the same time they were pungent. The PG barley treatment had a very "sweet" smell, with a slight slightly odor of ammonia. The corresponding K barley treatment was much more sour and pungent. The barley-whey treatments had the strongest and most definite associated odor. The smell was a mixture of a very sweet, 63 almost offensive odor, and the strange odor of chocolate while at the same time was very pungent. The distinct odor of the barley-whey silage may be a mixture of acetic acid with other unidentified volatiles including ketones and alcohols. Volatile fatty acids, a product of fermentation, are dependent upon the species of bacteria present which in turn are controlled by the amount and type of substrate (Yokoyama and Johnson, 1988). Table 7.5 shows the PG barley treatments had the largest concentrations of acetic, propionic, valeric acids and total VFA concentrations. Of the K PFW silages, the barley and hay-whey combinations had the largest concentrations of acetic acid, propionic acid, and total VFAs. Table 7.5 also shows that the barley, barley-whey and hay-whey combinations had more butyric acid than the control and hay PFW silages. Although butyric acid has no apparent adverse effect on the ruminant, butyric acid is usually associated with a clostridial fermentation and its presence is undesirable (Vetter and Von Glan, 1978). The wet substrate, low SCHO content, slow temperature increase and low acid conditions may have promoted the activity of Clostridia bacteria. In silages where lactate-fermenting Clostridia are dciminant the main fermentation acid i s butyric although acetic acid is also frequently present (McDonald, 1981). Clostridial silages have a 5.0-7.0 pH, low levels of lactate and SCHO, and are usually associated with wet materials. The optimum temperatures for lactic acid bacteria, and Clostridia and coliform growth is similar (37°C) ; however, lactic acid bacteria are more tolerant of temperatures less than 30° C (Vetter and Von Glan, 1978). The presence of butyric acid in well preserved silage is possible i f pH declines slowly with time. The PG barley silage also had a large concentration of propionic acid (Table 7.5). Because propionic acid is normally produced in low 64 concentrations in silages, propionic acid does not affect fermentation (Woolford, 1984). Propionic acid can inhibit the growth of Clostridia, Bacillus sp. and gram-negative bacteria (McDonald, 1981). At 1.5-6.0 g/1, propionic acid inhibited yeasts in a pure culture (Woolford, 1984). Propionic acid is an effective antimycotic agent and inhibits secondary aerobic deterioration (McDonald, 1981). Propionic acid also reduces ammonia N formation, decreases temperatures in ensiled grasses, legumes and haylage, stimulates growth of lactic acid bacteria and improves silage dry matter intakes (McDonald, 1981). The concentrations of isobutyric, isovaleric and valeric acids in the silages were small (Table 7.5). The PG control silages did not produce any detectable isobutyric acid. The deamination of branched chain amino acids by Clostridia i s associated with the formation of isobutyric and isovaleric acids. The relatively low crude protein content may have accounted for the minimal amounts of isobutyric and isovaleric acids formed in the PFW silages. Many of the rumen cellulolytic bacteria specifically require n-valeric, isobutyric, 2-methylbutyric or isovaleric acids (Yokoyama and Johnson, 1988). These VFAs are necessary for the formation of amino acids and long chain fatty acids which are incorporated into the c e l l wall of the bacteria (Yokoyama and Johnson, 1988). Butyric acid was the main VFA produced by the PG barley-whey and the PG hay-whey treatments. Possibly, in these silages, clostridial fermentation may have dominated the ensilage process. The majority of the total VFAs in the remaining treatments consisted of acetic with the individual silage and butyric acids in approximately similar proportions. The total VFA production varied treatments. In a well-preserved grass silage, a high molar proportion of acetic acid to butyric acid, with small amounts of isobutyric, valeric and isovaleric acids normally exists. The PFW 65 silages had comparatively less acetic, more butyric and more propionic acid, and had similar amounts of the isobutyric, isovaleric and valeric acids when measured on a molar percentage. Since neither acetic, propionic or butyric acid dominated these silages, i t i s possible that a wide range of reactions were responsible for the acid production. The control silages had lower tenperatures during ensiling (Table 7.3), no associated odor, lacked any change in acidity (K control: pH = 9.22; K PFW: pH = 9.40), and lacked the production of volatile fatty acids (Tables 7.5). The lack of microbial activity indicated no fermentation occurred. This lack of microbial activity may be due to the lack of available nitrogen, water soluble carbohydrates, and/or a suitable microflora population. Therefore, without additives, the PFW substrate appeared to be inert. In the control and hay K PFW treatments, lack of available nitrogen (Table 7.4) would suppress the proliferation rate of the microbes and affect the fermentation. The minimum nitrogen requirement for efficient lignocellulose breakdown in roughages was 0.6-0.8% (Pigden and Heaney, 1969). Cellulose breakdown in the rumen of cows was greatly accelerated with the addition of 0.1-0.2% nitrogen in the form of urea to an oat straw diet containing 0.55% rdtrogen (Pigden and Heaney, 1969). In normal well preserved silages the bacteria which attain dominance in the silage are associated with the fresh grass. Chlorine dioxide which is used in the bleaching process of pulp has been shown to inhibit silage bacteria at 2.98 mM but had only a marginal activity against yeasts and molds (Woolford, 1978). Fermentation in the treated silages was likely due to the microflora associated with the additives. In this experiment, the additives in the PFW silages acted as both a nutrient source and as an inoculum. 66 Although many of the raw carbohyclrate components are broken down into VFAs in the rumen, the large proportion of VFAs present in the feed likely are lost in the feeding bunk so the animal receives l i t t l e benefit from the high concentrations per se. However, the high concentrations of VFAs in the silage indicate same microbial activity in the silage has occurred. Assuming the silage microflora did not use a l l the raw substrate for the production of end products which are lost to the host, ensiling may enhance the substrate in terms of digestion. Although the silage microbes probably used up the readily available SCHO and protein, a "predigestion" of other components may be possible. The overall digestibility of the ensiled mixture may be greater than a similar non-ensiled mixture. This depends on the amount of potentially undegraded energy rich material which would pass through the rumen because of insufficient retention time in the rumen for complete digestion. Croy and Rode (1985) showed the in sacco dry matter digestibilities of PFW increased with time. At 12 and 24 hours the dry matter digestibilities of the K PFW and PG PFW were respectively 26.5% and 57.9%, and 18.5% and 76.2% (Croy and Rode, 1988). The microflora in the silage may also contribute to the establishment of a suitable rumen microflora early in feeding. The losses which occur in the treated silages may be expensive, but the potential improvement in digestibility may warrant ensiling the material with an additive. Losses of the nutritive components during ensilage are attributed to respiration by enzymes associated with the additives or substrate, fermentation by microorganisms, effluent losses .which affect the DM content and nutrient content, the density of the silo, sealing of the silo, and substrate suitability, illustrate the possible Table 7.4 shows the recoveries of the individual nutritive components to losses which occur during the ensiling process. Matter can not be created during ensiling. It is possible to lose matter (ie. through effluent and 67 volatiles) and for the original material to change form. Thus, i f no changes occur and a l l the dry matter will be accounted for, the recovery of an individual nutrient should be 100%. However, i f gaseous end products which are unaccounted for in the final dry matter are significant, the final dry matter values may be underestimated. Although the dry matters were corrected for VFA losses during drying, other volatile losses such as lactic acid, ammonia, carbon dioxide, methane and hydrogen were not measured. If these end products are large, the remaining nutritive components may be overestimated. This would account for recoveries (ie. CP and ADF) greater than 100% which are theoretically impossible. A dry matter recovery greater than 100% may be possible i f there is a loss of water as effluent, or i f water is used in any fermentation or oxidation reactions during the ensiling process. Table 7.4 shows the volatile fatty acids account for 0.03-10.39% of the total dry matter. The loss of ammonia N as a percentage of the total dry matter wil l likely be small since only a small fraction of the i n i t i a l dry matter of the PFW silages is CP. However, losses due to carbon dioxide and lactic acid may be significant. The average total dry matter losses in Italian ryegrass silage due to carbon dioxide was 1.1-1.9% (McDonald et al., 1968) and lactic acid ranged from 0.92-5.5% (MacDonald et al., 1968). After oven drying silage samples at 100°F over night, lactic acid was shown to be 1.4-16.4% volatile. Although lactic acid is less volatile than VFAs, lactic acid i s usually present in larger quantities, so the losses during drying may be significant (McDonald and Dewar, 1960). McDonald and Dewar (1960) showed that total and volatiles in silage may range from 1.98-8.80% of the corrected dry matter, were highest in silages with high pH containing relatively high amounts of butyric acid and volatile N. 68 Table 7.4 shows that the PG and K controls and K barley treatments had a SCHO recovery greater than 100%. Exact measurement of water soluble carbohydrate losses is difficult since sugar losses through respiration may be partially replaced by sugars released from polysaccharide hydrolysis (McDonald, 1981). Figure 7.2 shows that in cases where the i n i t i a l SCHO content is less than 1.19% of the total dry matter, the final SCHO proportion exceeds the original concentration. Thus in these cases (PG and K controls, and K barley) the formation of SCHO may have been possible from secondary sources (Figure 7.1). Figure 7.2 also shows that in silages where SCHO was abundant, this "extra" SCHO was used during the ensilage processes. The final concentrations of SCHO in a l l silages were between 1.19-2.24% (Table 7.4). In these cases i f secondary production of SCHO occurred, i t s formation rate was less than the rate of degradation. Pigden and Heaney (1969) suggested that there was a requirement for a small amount of readily fermentable carbohydrate to stimulate the fermentation of the lignocellulose complex. However, larger amounts of readily fermentable material frequently depressed lignocellulose utilization possibly because of competition between different microbial populations. The recovery of hemicellulose ranged from 66.23-88.14% in the PG silages, and 63.78-107.51% in the K silages. The PG and K controls, K hay and K hay-whey which have i n i t i a l SCHO values of 0.59%-3.81% show a loss of ADF ranging between 92.72-98.34%. The remaining treatments showed recoveries ranging from 100.79-113.58%. Figure 7.1 shows a possible schematic of the carbohydrate breakdown and fermentation of pulp mill fiber waste during ensilage. The recovery of soluble carbohydrates and hemicellulose is dependent upon the conversion rate of cellulose to hemicellulose and soluble carbohydrates; hemicellulose to soluble 69 carbohydrates; and hemicellulose and soluble carbohydrates to the final end products (Figure 7.1). Possibly the lack of easily fermentable carbohydrates and hemicellulose, resulted in a proliferation of a cellulolytic microbial population which thrived on the abundance of readily available cellulose. Conrad and Hibbs (1953) showed crude fiber digestibility increased when lew levels of readily fermentable carbohydrates were included in a ration. Microbial degradation of structural carbohydrates is limited by phenolic compounds such as lignin (Akin, 1986). However, since l i t t l e lignin was present in PFW (Croy and Rode, 1988), cellulose may be available for utilization by silage microbes. Commercial cellulases on ensiled alfalfa and imnature barley resulted in higher pH levels and DM losses in treated silages (Leatherwood et a l . , 1959). Henderson and MacDonald (1977) used cellulases to increase the supply of readily available carbohydrates for ensiling. Mushrooms have been observed to grow independently on the PFW. Fungi, as well as cellulytic bacteria, contain cellulases (Akin, 1986). Fungi, i f present in the PFW, may be also partly responsible for the breakdown of the cellulosic fraction and a loss in dry matter in the silages. Molds have also been shown to hydrolyze and metabolize cellulose and other c e l l wall components (McDonald, 1981). Although mold growth was minimal and restricted to the top and side surfaces of the PFW silages, yeasts and molds could contribute to the digestion of the fiber component. 7 . 4 . 2 D I S C U S S I O N : E F F L U E N T S Silo effluents were composited masking any changes with time. Although the PG control had a similar final dry matter to the PG treatments (Table 7.4), the PG control did not yield any effluent. The additives with the PG PFW favored the production of the effluent. Dexter (1961) showed silage 70 moisture could be bound by incorporating drier material at ensilage, straws and hays retaining more moisture than ground cereals. Extrapolation the values from Table 7.6, the PG barley, PG hay, PG barley-whey, and PG hay-whey PFW silage treatments would be expected to lose respectively 59, 45, 50 and 23.8 kg of effluent per tonne. These effluent losses correspond to losses of less than 0.5% of the total dry matter. This loss i s very small compared to effluent losses of 2.33-8.26% of the dry matter with orchardgrass silage (DM = 15.7-24.4%) as reported by Fisher et a l . (1981). None of the K PFW silages yielded effluents, even though water had been added prior to ensiling to increase the moisture content. The original dry matter of the PG PFW was 20.08% and the K PFW was 38.74%. Very l i t t l e effluent is produced from herbages with 25% DM (McDonald, 1981). No effluent is predicted to be formed from herbage with 29% DM. Perhaps the amount of moisture, the possible saturation of hay and barley, or the differing absorption properties of the PFWs account for the differences in ALCOHOLS Figure 7.1 Possible schematic model of the breakdown of the carbohydrate fractions in pulp mill waste silages during fermentation. % SCHO OF TOTAL DRY MATTER PQC KC KB PQB KBW PQBW KH KHW PQH PQHW PFW SILAQE TREATMENTS WkM B E F O R E E N S I L I N G ^1 A F T E R E N S I L I N G Figure 7.2 Water soluble carbohydrate (SCHO) content (as percentages of the total dry matter) in pulp mill fiber waste mixtures before and after ensiling for 70 days. (Values are taken from Table 7.4) the retention of moisture between the different PFW treatments. The volume of effluent produced, although mainly affected by the DM content of the ensiled crop, also is affected by the type of silo, the degree of consolidation, the pressure applied to the surface, and the use of additives (McDonald, 1981). On a dry matter basis, ash and crude protein were the main components in the effluent (Table 7.7). Less than 1% VFAs were present in the effluents (Table 7.7). Acetic and butyric acid made up approximately two-tjiirds of the VFAs produced, with less propionic acid, and very small amounts of isovaleric, isobutyric and valeric acids (Table 7.7). The effluent should reflect the fermentation process in order to give a reliable picture of the status of the silage. The total VFA concentrations, pH and CP were positively correlated between silage and effluent (Table 7.8). However, the individual VFAs in the effluent did not correlate to the silage VFAs (Table 7.8). Possibly secondary yeast and mold development and/or losses during the collection of VFAs altered the concentrations. 72 7.5 SUMMARY Because of the high moisture content of the PFW, ensiling was tested as a possible preservation and storage technique. The amount of moisture in the silage affects the total bacterial count and the fermentation rate (McDonald, 1981). A certain amount of moisture is essential for the proliferation of desirable micrcorganisms, but an excess encourages the growth of undesirable types (Woolford, 1984). Microbiological studies or microorganism counts on the PFW silages are recommended to determine further the type of fermentation which occurred within the silos. M.E. McCullough (1978) defined "silage quality" by the success of the fermentation rather than the feeding value of the silage. However, silage quality and the nutritional value of the silage are often highly correlated (McCullough, 1978). A good silage minimizes the change in nutrient value and the losses which affect the utilization of the silage and eventual production of the livestock. The lack of change in chemical composition indicated that the control PFW silages did not ferment. The treated silages, however, showed some degree of fermentation evidenced by the production of volatile fatty acids. Although the low SCHO content, low protein and high moisture of the resulting treated silages (with the exception of the PG hay-whey and PG barley-whey treatments) were prone to clostridial fermentation , the distribution of acetic, propionic and butyric acid concentrations indicated that clostridial bacteria did not dominate the fermentation. Of the treated silages, PG barley-whey treatment had the highest temperatures during ensiling, the lowest pH and the highest CP content. The microflora, the resulting fermentation and the final composition of the silage were influenced by the low SCHO and DM contents, the slow temperature rise, the type of additive, and the availability of cellulose as a substrate. 73 To test for treatment differences, silages with similar proportions but differing additives would have to be tested. A control with urea would be necessary to study the effect of nitrogen as a limiting factor versus the effect of the other additional additives. Rations incorporating PFW silages require a protein supplement because of the low CP level present in the silages. The high proportion of available fiber makes the PFW and corresponding silage an excellent potential energy source for ruminants. Secondary or clostridial fermentation associated with low dry matter silages may result in low dry matter intakes and reduced digestibilities. The effect on palatability and digestibility of ensiling PFW should be determined to assess the overall suitability of this method of storage. C H A P T E R E I G H T 74 8 . 0 M E A S U R I N G A P P A R E N T D I G E S T I B I L I T Y O P P U L P M I L L F I B E R W A S T E S I L A G E S U S I N G W E T H E R S H E E P 8 . 1 I N T R O D U C T I O N The n u t r i t i v e value o f a p a r t i c u l a r feed depends on the voluntary-intake, the p r o p o r t i o n digested and the e f f i c i e n c y w i t h which the d i g e s t e d n u t r i e n t s i n the f e e d s t u f f are absorbed by the animal (Woolford, 1984). These f a c t o r s i n t u r n determine animal performance. In t h i s experiment, the apparent dry matter, n e u t r a l detergent f i b e r , and a c i d detergent f i b e r d i g e s t i b i l i t i e s , as w e l l as the v o l u n t a r y intake o f PFW s i l a g e s by wether sheep were estimated t o f u r t h e r evaluate the n u t r i t i v e q u a l i t y o f PFW as a ruminant f e e d s t u f f . A comparison o f e n s i l i n g versus simple bulk p i l i n g was a l s o undertaken. 8 . 2 M A T E R I A L S A N D M E T H O D S 8.2.1 PREPARATION OF PFW SILAGES PG PFW and K PFW were obtained i n A p r i l 1986. These pulp residues, as r e c e i v e d from the pulp m i l l s , were chopped with a s c r e e n l e s s shredder/grinder^. The PFWs were mixed with b a r l e y o r hay, and urea. L i q u i d cottage cheese whey o r water was a l s o added. Proportions o f PFW and other i n g r e d i e n t s used i n the e i g h t PFW treatment mixtures are shown i n Table 8.1. Water was added t o adjust the moisture content o f the K PFW t o t h a t o f the PG PFW. The PFW treatments were mixed i n a mixer-feeder. The mixtures were packed i n t o polyethylene l i n e d permatube s i l o s (1.83 m x 0.76 m) and sealed. 1 - "Mighty Mac" composite shredder/grinder, Amerind Mackissic, Parker Ford, Pennsylvania 75 Table 8.1 Dry matter proportions (%) of the ingredients used in the pulp mill waste (PFW) treatments TREATMENT PG PFW1 K PFW2 BARLEY HAY WHEY UREA PG NON-ENSILED 64.4 - 28.8*3 - 5.3* 1.5* PG BARLEY 68.0 - 30.5 - - 1.5 PG HAY 68.0 - - 30.5 - 1.5 PG BARLEY-WHEY 64.4 — 28.8 — 5.3 1.5 K NON-ENSILED — 65.0 28.8* — 5.3* 1.5* K BARLEY - 68.6 29.9 - - 1.5 K HAY - 68.5 - 30.0 - 1.5 K BARLEY-WHEY - 65.0 28.3 - 5.3 1.5 1 - Prince George pulp mill fiber waste 2 - Kamloops pulp mill fiber waste 3 - * denotes ingredient was added after ensiling period Each si l o contained 455 kg of wet material. Temperature probes were inserted 0.6 m and 1.2 m from the bottom of the 1.8 m silos. A drum partially f i l l e d with water (approximately 135 kg) was used as a weight on the top of each silo. Drainage tubes at the base of each si l o allowed any leached effluent to be collected. The silos were covered with 4 mm clear polyethylene to avoid water damage to the permatubes and to avoid water collecting inside the silos. Two 455 kg piles of PG PFW and K PFW made up the remaining 2 treatments tested. The piles were no higher than 1.0 m. An open ended black plastic tent provided shelter while s t i l l allowing air circulation around the piles of PFW. Two temperature probes were placed in each pile. The piles and silos were placed outdoors, at random, in a line on an uncovered concrete pad. The silos remained sealed for 49 days. Air temperature and residue treatment temperatures were monitored twice daily during this period. 2 - "Knight Little Auggie" mixer-feeder, Broadhead LA 9, Knight Manufacturing Corp., Broadhead, Wisconsin, USA. 76 8.2.2 PREPARATION OF THE PFW RATIONS A l l hay used in the rations was processed using a grinder-mixer^. Forty percent of the hay used ground with a 3 mm screen and the remaining 60% with a 19 mm screen. After the ensiling period and prior to the final mixing of the complete rations, the PFW mixtures were chopped again with the same shredder/grinder as was previously used. Each time the rations were mixed, PFW silage samples were taken for chemical analyses. The PFW mixtures and early cut alfalfa hay in a 3:7 ratio were mixed in a tub grinder-mixer2 • In preliminary studies, animals accepted the PFW more readily when thoroughly coated with hay. However, to ensure minimal digestive upsets, coarse hay was also provided in the diet. Of the hay used, 40% was fine ground and 60% was coarse ground. To the non-ensiled PFWs, barley, whey and urea were also added in the proportions indicated in Table 8.1. Test rations contained approximately 20% PFW. A two week supply of feed was prepared at each mixing. Prepared feeds were stored in plastic bags in a cooler until they were used. Two control rations were also included. These basal rations contained 40% fine and 60% coarse chopped alfalfa hay which had been processed similarly to the hay used in the PFW rations. One batch of hay was used in the f i r s t three of five periods, and a second batch of hay was used in the last two periods. Each hay made up one of the two basal control diets. 1 - International Harvester Grinder-Mixer model 1050, J.I. Case Corp., 700 State St., Racine, Wisconsin, USA, 53404. 2 - New Holland tub grinder-mixer, Ford-New Holland Inc., 500 Diller Ave., New Holland, PA., USA, 17557. 77 A l l rations were supplemented with Swifts brand mineral pre-mix^ for the f i r s t three of five periods and with Shur Gain Essential Mineral^ for the last two periods of the t r i a l according to manufacturers specifications. 8.2.3 SHEEP DIGESTIBILITY TRIAL Yearling Suffolk-cross wether sheep (43-67 kg) were used in the digestibility t r i a l . At the beginning of the t r i a l , the sheep were shorn, deloused, treated for worms with Tramisol3 and vaccinated with Clostri-bac 7 with Havlogen4. Animals were housed indoors in individual stalls. Animals were fitted with harnesses and feces collection bags. The animals were fed twice daily and were given free access to water. The apparent digestibilities of the ten rations were measured by total feed and fecal collection using 12 sheep over five 20 day periods. Each ration constituted one treatment. During each period, three sheep were fed the same kind of ration. Each treatment had a total of six observations. Each 20 day period in the digestibility t r i a l included a five day adaptation phase (ad libitum intake), and a five day intake phase. During this five day phase, animals were offered 110% of their ad libitum intake and their voluntary intake was measured. The amount of feed offered was reduced to 80% of ad libitum consumption for the last ten days of the period. Total feed and total feces were measured during the final six days of the period. Feed, orts (uneaten feed) and feces were sampled for chemical analyses. 1 - New Life Feeds, Parrish and Heimbecker Ltd., Winnipeg, Man., Canada 2 - Shur Gain Division, Canada Packers Inc., Toronto, Ont., Canada 3 - Cyanamid Canada Inc., 2255 Sheppard Ave. E., Willowdale, Ont., Canada 4 - Haver-Lockhart Lab., Bayvet Division, Shawnee, Kansas, 66201 78 The digestibilities of the PFW silages were found by calculating the difference between the digestibilities of the rations as fed and the appropriate hay control using the method of weighted means. Weekly composite samples of PFW mixtures, feed, orts and feces were analyzed for DM, NDF, ADF, ash, SCHO, and pH (Chapter 7.2). CP was measured with the tecator block digest method of Parkinson and Allen (1975), and the amount of nitrogen present was determined by a Technicon AutoAnalyzer. Gross energy (GE) values of PFW samples were determined by bomb adiabatic calorimeter. 8.2.4 MEASUREMENT OF GAS PRODUCTION IN PFW SILAGE-HAY RATIONS Gas productions in K PFW barley-whey silage and in K PFW barley-whey silage-hay mixtures were measured over a nine day period. The latter mixture contained, on a dry matter basis, a 3:7 ratio of silage and alfalfa hay, to simulate the test rations. Adapting the procedure outlined by E l -Shazly and Hungate (1965), approximately 100 g of either substrate was packed tightly into glass bottles fitted with a rubber bung. Rubber tubing, inserted through the stopper, connected the jar to an inverted graduated cylinder f i l l e d with water which was placed in a partially water f i l l e d beaker. The amount of gas produced by the contents of the bottle was measured by the amount of water displaced in the cylinder. The bottle and tubing connections were sealed with silicone grease. Incubation temperatures simulated the conditions under which the rations were subjected prior to ingestion by the animals. Sequential temperatures for each sample included 30, 12 and 22 degrees C. Nitrogen (in the form of urea) equal to that in the PFW silage-hay mixture, was added to the silage without hay treatment after the original treatments had been exposed to a l l three temperatures. Gas production in the silage-urea mixture was compared 79 to that of the silage-hay mixture to determine the affect of nitrogen as the limiting factor on gas production. 8.2.5 STATISTICAL ANALYSES The Statistical Analysis System (SAS, 1985) general linear model (GLM) procedure was used to analyze the data. Differences in chemical composition between feed offered and orts were tested with a paired t-test. Analysis of variance was performed on ration compositions to determine treatment differences. As well, animal performance and digestibility coefficients were tested with analysis of variance. Treatment effects were treated as blocks. Differences between treatments were analyzed using the P DIFF least significant means at the 5% level of significance. 8.3 RESULTS Table 8.2 shows the chemical composition of the ingredients used in the PFW mixtures. The NDF and ADF contents of the PG PFW and K PFW were respectively 96.10% and 88.65%, and 91.58% and 86.50%. The K PFW contained almost twice as much ash as the PG PFW (12.71% and 6.26% respectively). The pH values of the PFWs in this t r i a l ranged from 4.30-6.69. Table 8.3 shows the minimum, maximum and Day 21 temperatures of the PFW mixtures during the 49 day ensiling period. Mirdmum temperatures which ranged between 3.6-6.7°C, were recorded within the f i r s t week of ensiling when air temperatures were also very low. During the fermentation period, the ensiled PFW mixtures attained maximum temperatures on Days 24-29. The maximum temperatures for the PG PFW and the K PFW non-ensiled treatments were 14.9°C and 12.5°C respectively. The maximum temperatures for the non-80 Table 8.2 Chemical composition of ingredients used in the pulp mill fiber (PFW) treatments (dry matter basis) INGREDIENT %DM1 pH %ASH %NDF %ADF %SCHO %CP GE WHEY 5. 332 4.43 14.58 _3 - 57.40 13. 44 -BARLEY 91. 34 - 2.95 20. 44 5.99 4.13 14. 44 -TIMOTHY 91. 56 - 6.56 58. 19 30.99 16.15 10. 00 -UREA 99. 66 - 2.00 0 0 0 245. 16 -PG PFW 17. 89 6.69 6.26 96. 10 88.65 0.49 0. 88 4008 K PFW 27. 12 4.30 12.71 91. 58 86.50 0.27 1. 00 4098 1 -DM = dry matter; NDF = neutral detergent fiber; ADF = acid detergent fiber; SCHO = water soluble carbohydrates; CP = crude protein; GE = gross energy (kcal/g). 2 - values represent mean of single samples analyzed in duplicate. 3 - not analyzed. Table 8.3 Temperatures (degrees C) of the pulp mill fiber waste (PFW) treatments over a 49 day ensilage period TREATMENT MINIMUM MAXIMUM DAY 21 PG NON-ENSILED1 4.2 (1)2 14 .9 (37) 11. 6 PG BARLEY 4.9 (6) 22 .4 (29) 16. 9 PG HAY 5.9 (6) 23 .4 (29) 17. 5 PG BARLEY + WHEY 5.7 (6) 20 .8 (29) 16. 3 K NON-ENSILED1 3.6 (2) 12 .5 (37) 9. 3 K BARLEY 5.4 (6) 22 .3 (24) 17. 9 K HAY 6.7 (6) 22 .8 (25) 18. 6 K BARLEY + WHEY 5.5 (6) 21 .3 (25) 16. 5 AIR TEMPERATURE 3.5 (4) 24 .0 (23) 20. 0 1 - pulp mill fiber waste piled under shelter. 2 - temperatures are the mean of two daily temperatures from two positions within the silo; tenperatures occurred on the day indicated within brackets. Day 0 refers to the day the mixtures were ensiled. ensiled material were recorded on Day 37, 8-13 days after the maximum tenperatures were attained by the ensiled treatments. The chemical composition of the PFW mixtures after ensiling is shown in Table 8.4. The dry matters in the non-ensiled mixtures (46.6-54.2%) were higher than in the ensiled treatments (22.2-39.8%). The NDF content in the silages ranged from 81.36-91.66%, and the ADF content ranged from 73.07-81 Table 8.4 Chemical composition (on a dry matter basis) of pulp mill fiber waste mixtures after ensiling treatment %DM1 %ASH %NDF %ADF %SCHO %CP PH PG NON-ENSILED 54 .2 7. 12 91. 66 87. 78 0.43 1.00 7. .03 PG BARLEY 39 .8 5. 94 83. 55 76. 98 0.63 6.06 4. .48 PG HAY 22 .2 7. 95 85. 91 74. 80 0.37 4.81 5. .06 PG BARLEY-WHEY 24 .4 7. 80 84. 32 74. 18 0.43 6.31 4, .68 K NON-ENSILED 46 .6 12. 80 91. 03 85. 72 0.15 0.88 8. .80 K BARLEY 23 .3 11. 78 85. 14 77. 33 0.63 5.00 4. .28 K HAY 25 .0 15. 01 84. 28 73. 07 0.36 5.00 6. .81 K BARLEY-WHEY 27 .2 13. 10 81. 36 74. 09 0.43 5.25 6. .52 1 - DM = dry matter; NDF = neutral detergent fiber; ADF = acid detergent fiber; SCHO = water soluble carbohydrate; CP = crude protein. 2 - composited samples analyzed in duplicate. Table 8.5 Chemical composition (on a dry matter basis) of pulp mill fiber rations fed to wether sheep RATION %DM %ASH %NDF %ADF %SCHO %CP PH CONTROL 1 91. 2cl 8. 97a 48 .56a 37. 23a 5. 96a 18. 14e 5. 78a CONTROL 2 91. 5c 9. 97b 45 • 47a 34. 70a 6. 52a 17. 08de 5. 75a PG NON-ENSILED 57. Oab 8. 72a 61 .23bc 52. 10c 3. 27a 15. 06abc 5. 62a PG BARLEY 55. 9ab i 8. 69a 57 .00bc 49. 28bc 4. 53a 16. 16cd 5. 44a PG HAY 48. 5a 9. 04a 62 .22bc 51. 12bc 2. 80a 13. 83a 5. 41a PG BARLEY-WHEY 51. 3a 8. 67a 58 .41bc 50. 79bc 3. 66a 14. 46ab 5. 18a K NON-ENSILED 64. 2b 10. 30b 63 .15c 45. 69b 3. 98a 15. 87c 6. 14a K BARLEY 52. la 10. 23b 57 .65bc 49. 93bc 3. 63a 15. 39bc 5. 87a K HAY 52. 3a 10. 23b 58 • 60bc 50. 65bc 3. 71a 14. Olab 5. 76a K BARLEY-WHEY 54. 0a 10. 52b 55 .78b 47. 67bc 3. 89a 15. 85c 5. 68a standard error 2. 8 0. 14 2 .09 1. 73 0. 63 0. 43 0. 19 1 - values represent mean of weekly composite feed sample taken from 2 different feeding periods; within a given column, values with different letters differ significantly (P < 0.05). 87.78%. CP made up 0.88-6.06% of the total dry matter. The pH values ranged from 4.28-8.80. The ash content ranged from 5.94-7.95% in the PG PFW mixtures, and from 11.78-15.01% in the K PFW mixtures. The overall dry matters of the PFW rations (Table 8.5) ranged from 48.5% to 64.2%. The ash contents of the K PFW rations were significantly higher than in the PG PFW rations. The K non-ensiled treatment had a significantly 82 higher NDF content than the K barley-whey treatment. The PG non-ensiled treatment had a significantly higher ADF content than the K non-ensiled treatment. No other significant differences in NDF or ADF were detected between the remaining PFW rations. Both NDF and ADF in the PFW rations were significantly higher than in the control rations. A l l rations had a CP content greater than 13.83%. No significant differences in pH and SCHO content of the rations were detected. Table 8.6 Chemical composition (on a dry matter basis) of orts (refused feed) RATION %ASH ± SD %NDF ± SD CONTROL 1 11. 70 + 2. 29 1 46. 27 + 3. 09 CONTROL 2 10. 44 + 0. 81 45. 55 + 3. 97 PG NON-ENSILED 9. 54 + 0. 91 73. 08 + 6. 07* PG BARLEY 11. 20 + 1. 42 57. 32 + 3. 25 PG HAY 10. 48 + 1. 00 59. 75 + 3. 82 PG BARLEY-WHEY 10. 44 + 0. 81 * 2 56. 07 + 2. 14 K NON-ENSILED 12. 30 + 1. 19 59. 87 + 3. 39 K BARLEY 12. 74 + 0. 77 * 57. 81 + 4. 04 K HAY 12. 12 + 0. 99 * 58. 55 + 1. 34 K BARLEY-WHEY 12. 20 + 1. 00 59. 43 + 3. 12 1 - mean values ± standard deviation of 6 animals represent composited weekly samples analyzed in duplicate. 2 - * denotes significant difference (P < 0.05) between nutrient in the ration offered (Table 8.5) and nutrient in the orts. Table 8.6 shows the ash and NDF content of the orts. The PG barley-whey, K barley and K hay rations had significantly higher ash contents in the orts compared to total offered feed. Only the PG non-ensiled ration showed a significantly higher NDF content in the refused feed versus the offered feed. 83 Table 8.7 Average daily gain (AEG) and ad libutum intake of sheep fed test rations, and apparent dry matter digestibilities (CMD) of the complete rations RATIONS ADG ± SEM INTAKE + SEM DMD ± SEM (kg/D) (kg) (%) CONTROL 1 0.19 a 1 ± 0.082 2.50 a + 0.15 60.43 bed + 1.62 CONTROL 2 0.09 a ± 0.07 2.23 a + 0.13 59.76 bed + 1.62 PG NON-ENSILED 0.24 a ± 0.08 2.14 a + 0.15 56.23 ab + 1.62 PG BARLEY 0.30 a ± 0.09 2.47 a + 0.16 60.59 bed + 1.62 PG HAY 0.00 a ± 0.07 2.30 a + 0.13 61.35 cd + 1.62 PG BARLEY-WHEY 0.08 a ± 0.08 2.38 a + 0.15 63.63 d + 1.62 K NON-ENSILED 0.09 a ± 0.07 1.87 a + 0.13 57.52 abc + 1.62 K BARLEY 0.20 a ± 0.08 2.22 a + 0.15 59.81 bed + 1.77 K HAY 0.04 a ± 0.07 2.09 a + 0.13 54.67 a + 1.62 K BARLEY-WHEY 0.14 a ± 0.07 2.07 a + 0.13 61.09 cd + 1.62 1 - within a given column, values with different letters differ significantly (P < 0.05). 2 - values are the least squares means ± standard error of the mean; values represent the mean of 6 observations. Table 8.8 Apparent dry matter digestibilities (SDMD), apparent neutral detergent fiber digestibilities (SNDFD) and apparent acid detergent fiber digestibilities (SADFD) of pulp mill waste silages RATIONS SDMD ± SEM SADFD ± SEM SNDFD ± SEM (%) (%) (%) CONTROL 1 60. 43 bed 1 + 5. 1 92 43 .70 ab + 8. .06 47. 50 ab + 9. 92 CONTROL 2 59. 76 bed + 5. 19 40 .36 a + 7, .36 43. 34 a + 9. 05 PG NON-ENSILED 46. 42 ab + 5. 19 69 .45 cd + 8. .06 86. 59 cd + 9. 92 PG BARLEY 60. 95 bed + 5. 19 98 .40 de + 9. .01 86. 85 cd + 11. 09 PG HAY 65. 07 cd + 5. 19 72 .50 cd + 7. ,36 118. 11 e + 9. 05 PG BARLEY-WHEY 71. 89 d + 5. 19 103 .41 e + 8. ,06 99. 94 de + 9. 92 K NON-ENSILED 51. 51 abc + 5. 19 64 .31 be + 7. ,36 69. 71 be + 9. 05 K BARLEY 58. 36 bed + 5. 68 80 .66 cde + 8. .05 80. 34 c + 9. 92 K HAY 42. 01 a + 5. 19 72 .87 cd + 7. .36 71. 45 be + 9. 05 K BARLEY-WHEY 63. 42 cd + 5. 19 85 .51 de + 7. ,36 81. 53 cd + 9. 05 1 - within a given column, values with different letters differ significantly (P < 0.05). 2 - values are least squared means ± standard error of the mean; values represent the mean of 6 observations. 84 Table 8.7 shews that voluntary intakes of the sheep ranged from 1.86-2.46 kg/D. No significant treatment differences were detected in intake. However, intake tended to be lowest in the K non-ensiled treatment (1.86 kg/D), the K barley-whey (2.07 kg/D), and the K hay (2.09 kg/D) treatments. Table 8.7 also shows no difference in average daily gain (ADG) among animals on the various treatments. The apparent dry matter digestibility of the PFW rations (DMD) ranged from 54.67% in the K hay ration to 63.63% in the PG barley-whey ration. The DMD of the K hay ration was significantly lower than the control rations but not the non-ensiled treatments. The DMD the PG barley-whey ration was higher than in the non-ensiled and the K hay rations. The apparent digestibilities of dry matter (SDMD) and fiber components for the PFW silages are summarized in Table 8.8. The SDMD of the K hay silage (42.01%) did not differ from the non-ensiled treatments, but did have a significantly lower SDMD than the control rations (59.76% and 60.43%). The PG barley-whey silage had the highest SDMD (71.89%). The apparent ADF digestibilities of the PFW silages (SADFD) ranged from 65.20% in the K hay silage to 103.41% in the PG barley-whey treatment. The PG barley and PG barley-whey silages had SADFD coefficients approaching or greater than 100%. The apparent ADF digestibility coefficients of the hay control diet were 43.70 and 40.36%. The apparent NDF digestibilities of the PFW silages (SNDFD), excluding the K non-ensiled and K hay silages, were significantly higher than the control rations. The SNDFD of the PFW silages ranged from 69.71% in the K non-ensiled silage to 118.11% in the PG hay silage. Although the 118% value was high, statistically there was no difference between 118% (PG hay) and 99% (PG barley-whey). Theoretically both values indicate the NDF portion of the silage has been completely digested. Figure 8.1 illustrates the gas production rates of K PFW barley-whey silage-alfalfa hay mixture when incubated at various temperatures. The 85 negative control, containing PFW silage without hay, did not produce any measurable gas during the incubation period. The gas production rates of the PFW-silage hay inixture (100 g) at 30° C for the f i r s t 40 hours of incubation increased from zero to 1860 nlitres per nr. When the incubation temperature dropped to 12° C, no measurable gas was produced. However, at 22° C gas production increased again to 1582 nlitres per hour within three hours, decreasing to zero over the following five hours. Within the f i r s t seven hours at 30 C, gas production reached a maximum of 857 nlitres per hour which decreased over the last 17 hours. When urea was added to the negative control after 206 hours of incubation, gas production was considerably less than when the PFW silage had been mixed with hay. For the f i r s t 27.8 hours after urea was introduced to the PFW silage, gas production rate reached a maximum of 50 nlitres per hour which decreased to less than four nlitres over a 52 hour period. 86 MICROLITRES GAS / HR / 100 G 1 8 0 0 1 6 0 0 1 4 0 0 1 2 0 0 1 0 0 0 8 0 0 6 0 0 4 0 0 2 0 0 0 30 D E G R E E S C 12 D E G R E E S C I 22 D E G R E E S C I 1 1 5 0 100 150 TIME IN HOURS 30 D E G R E E S C 2 0 0 250 Figure 8.1 Gas production rates by 100 grams of Kamloops barley-whey pulp fiber waste silage-alfalfa hay substrate at various temperatures over a 206 hour incubation period 8 .4 DISCUSSION The NDF and ADF contents of the silages (Table 8.4) were not as high in the original PFW (Table 8.2) due to the dilution effect of the other silage ingredients. The NDF and ADF contents were, however, similar within the different PFW rations, but larger than the control rations (Table 8.5). The K PFW rations had a higher ash content (10.23-10.52%) compared to the PG PFW rations (8.64-9.04) (Table 8.6). This difference reflected the differences in ash found in the original PFW (Table 8.2). The higher ash content may have a slightly negative affect on the dry matter digestibility of the K PFW rations. The large variation in CP and pH of the PFW silage was apparently due to errors in sampling. The coefficients for SDMD, SADFD and SNDFD, in most cases, were equivalent to or higher than those for the hay control rations (Table 8.8). 87 This high digestibility was expected because of the changes which occurred in the wood during the pulping process. Baker (1973) showed that the extent of delignification radically influenced fiber digestibility (Baker, 1973). The organic matter and cellulose digestibilities of diets containing paper fed to sheep were higher than in the corresponding hay control rations (Coombe and Briggs, 1974). Lemieux and Wilson (1979) also the fiber showed that the fiber components in the PFW diets were more digestible than components in the control diets. As well, NDF and ADF digestibility values were higher (P < 0.01) for the PFW diets than for the corresponding components of the hay-corn control fed animals (Lemieux and Wilson, 1979). The means of the SNDFD for the PG hay, and SADFD of the PG barley-whey silages were greater than 100%. The SDMD, SNDFD and SADFD coefficients of the PG barley-whey silages were 71.89%, 99.94% and 103.41% (Table 8.8). These values were similar to those reported by Croy and Rode (1988) who, based on regression analysis of digestibility coefficients of rations containing 0-48% PFW, predicted DM, NDF and ADF digestibilities of a ration containing 100% PFW to be 79.7%, 95.7% and 102% (Croy and Rode, 1985 and 1988). The digestibility of the PFW silage was estimated from the difference between the digestibility of the total ration and the digestibility of the hay controls. The value for the digestibility of the hay was treated as a constant. A change in the digestibility of the hay would affect the digestibility of the silage. Thus any increase in the digestibility of the total ration would have resulted in overestimating the digestibility of the PFW silage. The extremely high SADFD and SNDFD coefficients of the PFW silages (Table 8.8) may be explained by a number of factors. Any associative affects would have been excluded when the digestibility of the hay was 88 measured alone. If associative affects are present, the measured digestibility of the feedstuff mixture will not result in the same value as that determined by the digestibility of the weighted means (Conrad and Hibbs, 1953; Conrad et al., 1966; Putnam and Loosli, 1959; Dash et al., fermentative activity which is responsible for the increased digestibility 1974b). Church and Pond, 1982). Croy and Rode (1988) showed increasing trends in ADF and NDF digestibilities with increasing amounts of PFW in the ration. This could possibly be due to associative effects between the PFW and the other ingredients in the ration. Dietary components in the test diet may stimulate fermentative activity which i s responsible for the increased digestibility (Church and Pond, 1982). If an extremely large cellulolytic microbial population existed within the rumen a more complete digestion of the cellulose in the fiber fractions of the hay may have been possible. As well, partial fermentation and predigestion of nutrients in the PFW silage-hay ration may have occurred prior to feeding affecting the measured digestibility of the rations. In the preparation of the PFW rations, i f fermentation was possible when hay was added to PFW silage, the digestibility of the feedstuff may have been positively altered. The fermentation capacity of the mixture was measured under conditions similar to that to which the feedstuff was subjected prior to consumption. The rations were mixed outdoors in midsummer with air temperatures in the low thirties, and packed in black plastic bags. Although the bags of feed were stored in a cooler until use, cooling was not immediate. The bags of feed were removed from storage as required. The offered feed remained in the manger at room temperature until consumed by the animal or until the next morning when orts were collected. When the PFW silage was mixed with hay, gas production rates were greater than in the PFW silage alone. High temperatures enhanced gas 89 production (Figure 8.1). Gas production in the PFW silage-hay mixture and in PFW silage was measured as an indicator of fermentation and a measure of microbial activity. The amount of substrate fermented is a function of the fermentation products formed (El-Shazly and Hungate, 1965). The rates of gas production in this experiment were approximately 33 times less than the gas production measured in the rumen contents of lactating cows (El-Shazley and Hungate, 1965). No measurable gas was produced in the silage without hay during the incubation period. Because of the large sample size of PFW silage used, the variation between samples was assumed to be negligible. Any further fermentation in the silage alone may have been limited by nitrogen or soluble carbohydrate availability, or other unknown factors. When urea was added to this negative control a slight increase in gas production was observed. The gas production was, however, s t i l l lower than in the PFW silage-hay mixture. Possibly microflora associated with the hay may have acted as an inoculum to promote fermentation. The data suggests that fermentation in the PFW silage rations prior to feeding was possible, although the extent to which this increased microbial activity affected the digestibility of the substrate is not known. The fineness of the hay fraction of the ration appeared necessary to make the rations acceptable to the animals with minimal sorting. Grinding can affect feeding value of a ration. The intake of control rations as well as the PG ensiled rations were relatively high (Table 8.7). The voluntary intakes and the lack of high proportions of fibrous feeds in the refused feed (Table 8.6) would suggest that PFW was palatable. Pelleting the PFW rations to minimize sorting probably is not necessary. Two animals, one on the PG barley and one on the PG non-ensiled ration, had mild cases of diarrhoea. Fecal output of other PFW fed sheep were rather 90 soft, although pellets were s t i l l formed. Feces, when tested, were negative for worms. However, even among animals on similar diets there was a noticeable difference in the firmness of fecal pellets. The fine hay in the rations may have contributed to a shortened retention time of the feed in the rumen which affected the consistency of the feces. In addition, the increased rate of passage may have caused a decrease in digestibility, nutrient utilization by the microflora, and a decrease in the overall As well, perhaps out of boredom, rather than for physiological reasons, the sheep developed a habit of gnawing on their wooden managers. Possibly the combined diarrhoea and gnawing habits may have indicated that the sheep were craving roughage in their diets. Perhaps more coarse hay in their diet was necessary. A tendency toward scouring was noticed in animals when diets without any coarse roughage was fed (Dinius et a l . , 1970). Lemieux and Wilson (1979) reported the feces excreted by wethers receiving 60 and 67% PFW appeared to be wetter than animals fed the control ration and rations with 20% PFW. More roughage in a ration may slow the rate of passage, thereby having a further positive affect on digestibility. In this t r i a l , ADG was measured as an partial indicator of animal performance. Since intake was controlled during part of the feeding period, and the testing periods of the treatments were relatively short, likely no significant differences in ADG between treatments was detected (Table 8.7). Animal performance is influenced by dry matter intake and dry matter digestibility of the feed. Table 8.9 shows an estimation of the digestible energy a sheep would consume eating a ration of pure PFW silage. In the calculation of this value, the following assumptions were made: 1.) For the sake of comparison of the feeding values of the individual silages, the assumption was made that a ration containing 100% PFW silage would be accepted and animal performance would not be limited by the lack 91 protein, minerals or vitamins. 2. ) Treatment differences in intake and in digestible ADF measured in this t r i a l would hold constant for rations containing 100% PFW silage. 3. ) The energy contents of the digestible ADF were derived from the gross energy of the PFWs (Table 8.2). The energy contents of the digestible ADF in the silages were assumed to be constant from a particular source (PG or K), and would be similar in the different silages treatments. Prediction equations using proximate composition have been criticized, because each proximate nutrient is a mixture of materials which vary between feeds (Schneider and Flatt, 1975). However in PFW silages, ADF is the main component (Table 8.4). Since only a small fraction of this ADF fraction is lignin, the main energy source in the PFW silage is cellulose. Other digestible nutrients in the silages which occurred in small amounts (Table 8.4), although readily available for digestion, contributed only a small fraction of the total digestible energy of the various silages. These other digestible nutrients were not considered to affect treatment differences. Based on a modification of the procedure for calculating the Nutritive Value Index (NVI) (Crampton et al., 1960) and the Caloric Equivalent of NVI (Crampton and Harris, 1969), the digestible energy of the PFW silages was estimated. As a means of further evaluating the merit of PFW as a feedstuff, this value was used to compare and to predict relative performance when animals are fed different PFW silages. Equation 8.1 estimated the energy content of the ADF fraction in the PFW. This value was used as a constant in the calculation of the digestible energy intake. The digestible energy intake was then calculated according to Equation 8.2. 92 ASSUMPTIONS FOR THE ESTIMATION OF GROSS ENERGY FOR ADF IN PFW: I f the gross energy of PG PFW = 4.008 Mcal/kg, and the gross energy of K PFW = 4.098 Mcal/kg (Table 8.2), and, the heat of combustion (kcal/g) for the following chemical components is as follows (Atwater's values as cited by Lloyd et al., 1978): CARBOHYDRATES =4.15 kcal/g FAT = 9.40 kcal/g PROTEIN = 5.65 kcal/g Although these values may vary slightly depending on the specific foodstuff, the relative differences in energy content were assumed to remain constant. Therefore, the gross energy value of the protein fractions was 1.36X the carbohydrate fraction, and gross energy value of the fat fraction was 2.27X the carbohydrate fraction. Let, x = the gross energy of ADF = gross energy of SCHO = gross energy of the carbohydrate fraction. Since, the gross energy of a material i s the sum of the energy of the individual components, the gross energy content of the ADF portion of PFW can be calculated. EQUATION 8.1 ESTIMATE OF ENERGY CONTENT OF ADF FRACTION OF PFW CHOx + CP (1.36X) + FAT (2.27x) = GE WHERE: CHO = %SCHO in PFW CP = %CP in PFW FAT = %FAT in PFW GE = TOTAL GROSS ENERGY IN PFW Solving f o r x by substituting the values from Table 8.2, the gross energy of the ADF fraction i s : PG PFW: (0.8865)x + (0.0088)(1.36x) =4.008 x = 4.461 Mcal/kg K PFW: (0.8650)x + (0.0100)(1.36x) = 4.098 x = 4.664 Mcal/kg EQUATION 8.2 DIGESTIBLE ENERGY INTAKE X A * B * C where: X DIGESTIBLE ENERGY INTAKE (Mcal/D) A DIGESTIBLE ADF (kg/kg feed consumed) B FEED CONSUMED (kg/D) C GROSS ENERGY OF ADF FRACTION (Mcal/kg ADF) 94 Table 8.9 Predicted digestible energy (DE) intake of rations containing 100% of basis) PFW SILAGE DIGESTIBLE INTAKE GROSS ENERGY DE INTAKE ADF (kg/D)2 OF ADF (Mcal/D)4 (%)1 (Mcal/kg)3 PG NON-ENSILED 58. 60 2. 14 4. 461 5. 59 PG BARLEY 77. 60 2. 47 4. 461 8. 55 PG HAY 54. 16 2. 30 4. 461 5. 56 PG BARLEY-WHEY 88. 57 2. 38 4. 461 9. 72 K NON-ENSILED 61. 71 1. 87 4. 664 5. 38 K BARLEY 60. 29 2. 22 4. 664 6. 24 K HAY 47. 64 2. 09 4. 664 4. 64 K BARLEY-WHEY 69. 04 2. 07 4. 664 6. 67 1 - digestible ADF is the product of acid detergent fiber (ADF) content (Table 8.4) and its digestibility (SADFD) (Table 8.8) 2 - assumed intake of a ration cx»ntoining 100% PFW silage; values are taken from Table 8.7 3 - values are taken from Table 8.2 (calculated according to Equation 9.1) 4 - estimated digestible energy intake (calculated according to Equation 9.2) Table 8.9 shows similar trends in digestible energy intake between the treatments within the two PFW sources. Within limits, animals with higher digestible energy intakes would be expected to gain more weight at a quicker rate. The total digestible energy intake by sheep was greatest in the barley-whey combination, followed by the barley, the non-ensiled and hay treatments. The total intake of digestible energy of the various silage rations ranged from 4.64-9.72 Mcal/D. According to the NRC-NAS values (1985), replacement rams (40-80 kg) gaining 0.32 kg/D, would require 5.0-7.8 Mcal/D. Thus in terms of a pure energy requirement, PFW silage would be an excellent energy source. The non-ensiled PFWs had lower minimum, maximum and Day 20 temperatures than the ensiled treatments (Table 8.3). The lower temperatures in the non-ensiled treatments have been may partially content in the untreated PFW, or due to the lack of fermentation associated with a low SCHO and/or CP due to a large exposed surface:mass ratio. The non-ensiled PFW did not show any signs of deterioration during storage. However, the surface of this 95 material tended to dry out which made the PFW harder to mix with the other ingredients in the final ration. This may have accounted for the significantly higher proportion of NDF in the orts compared to the offered feed of the PG non-ensiled ration (Table 8.6). Ensiling the barley-whey combination significantly enhanced the DMD (PG barley whey 71.89%; K barley-whey 63.42%) over the non-ensiled treatments (PG non-ensiled 46.42%; K non-ensiled 51.51%) (Table 8.8). The higher temperatures attained in a relatively shorter time period in the ensiled treatments compared to the non-ensiled PFW (Table 8.3) would suggest that the addition of additives prior to ensiling the PFW promoted fermentation. These changes in fermentation are then responsible for the positive effect on digestibility of the silage (Table 8.8). As well, when digestibility and intake were considered, using digestible energy intake as an indicator, PFW ensiled with barley-whey-urea was a better feed than the piled PFW (non-ensiled) supplemented with barley and whey added prior to feeding (Table 8.9). In summary, PFW silages had high apparent DM, ADF, and NDF digestibilities as measured in sheep. These PFW silages were consumed readily by animals. In addition, the estimated digestible energy values of the PFW silages, calculated from the intake of digestible ADF, showed that PFW was a high energy feedstuff. Of the silage combinations tested, animals were expected to gain fastest when fed PFW ensiled with barley and whey. C H A P T E R N I N E 96 9 . 0 T H E E F F E C T O F W H E Y O N P R E S E R V A T I O N A N D D I G E S T I B I L I T Y O F P U L P M I L L F I B E R W A S T E S I L A G E 9 . 1 I N T R O D U C T I O N Whey is the watery portion which separates from the curds during the conventional manufacture of cheese. Whey from ripened cheese (Cheddar cheese) is "sweet" with a pH 5.9-6.3 and from fresh cheeses (cottage cheese) is "sour" or acidic with a pH of 4.4-4.6. In the previous two experiments (Chapters 7.0 and 8.0), ensiled PFW combined with various additives improved fermentation characteristics and increased the dry matter digestibility. Whey, as a silage additive, added at 5.3% of the dry matter to barley-urea PFW silage further enhanced the dry matter digestibility over similar silages without whey (Chapter 9.0). These results concurred with others (Allen et al. , 1939; Schingoethe, 1976; Dash et a l . , 1974c) who showed that the addition of whey improved the fermentation, quality and digestibility of grass and legume silages. The objective of this t r i a l was to determine an optimum level of whey to be combined with barley-urea PFW silage to achieve a quality fermentation and to support maximum animal performance based on intake and digestibility. 9 . 2 M A T E R I A L S A N D M E T H O D S 9.2.1 SILAGE PREPARATION PG PFW was obtained from the pulp mill in March 1987. The PFW was chopped with a forage harvester^ to break up any large clumps prior to ensiling. 1 - Fox Forage Harvester, model 1F546, Fox River Tractor Co., Appleton, Wisconsin, USA. 97 Four levels of whey (0, 2.7, 5.5, 10.8% of the total dry matter) with barley-urea PG PFW silage constituted the four treatments tested. In each treatment, whey replaced PFW. Water was added to equalize the moisture content in a l l treatments. Barley, urea and condensed Cheddar cheese whey were added to the PFW in the proportions shown in Table 9.1. The mixtures were packed in polyethylene lined permatube silos (0.90 m x 0.91 m). Each silo contained 600 kg of wet material. A drum partially f i l l e d with water (approximately 135 kg) was used as a weight on the top of each silo. The silos remained sealed for 40 days. Drainage tubes at the base of each silo allowed the effluent to be collected. The total effluents were weighed and sampled for analyses of DM, pH, ash, SCHO, VFA and CP. Temperature probes were inserted in the center of each silo. Air and silage temperatures were monitored twice daily during the fermentation period. Table 9.1 Dry matter proportions (%) of the ingredients used in the Prince George pulp mill waste (PG PFW) barley-whey silage treatments TREATMENT PG PFW BARLEY WHEY UREA 0% WHEY 77.5 21.5 0 1.0 2.7% WHEY 74.9 21.4 2.7 1.0 5.5% WHEY 72.2 21.3 5.5 1.0 10.8% WHEY 67.0 21.2 10.8 1.0 9.2.2 RATION PREPARATION After the fermentation period, the PFW silages were mixed in a horizontal ribbon mixer with alfalfa hay in a 3:7 ratio. The hay consisted of a mixture of 60% coarse chopped hayi and 40% ground alfalfa pellets. 1 - "Hay Buster", Model B, Minot, North Dakota 98 A two week supply of feed was prepared at one time. Prepared feeds were stored in plastic bags and frozen until use. Feed was removed from the freezer at least two days in advance of feeding to allow the silage to thaw. Complete feeds contained approximately 20.1-23.3% PFW depending on the whey level. Otter Sheep Mineral Mix^, Otter Trace Mineral Salt with selenium^, and sodium triphosphate were added to the rations according to the manufacturer's recommendations. Animals were given free access to iodine, cobaltized salt and fresh water. Animals were fed twice daily. 9.2.3 ANIMAL DIGESTIBILITY TRIAL Pregnant ewe sheep in their f i r s t trimester were housed indoors in individual metabolism cages. The apparent digestibilities of the four different silage treatments were measured by total feed and fecal collection using 12 sheep. Each ration constituted one treatment, and in each of two periods, each ration was fed to three sheep. A l l four treatments were fed in each of two periods. The sheep were adapted to the PFW rations over a four day period. The digestibility t r i a l consisted of two 22 day periods. Each period included a 5 day adaptation phase (ad libutum intake), and a 6 day intake phase. During this intake phase, animals were offered 110% of their ad libutum intake and their voluntary intake was measured. For the remaining 11 days of the period, the amount of feed offered was reduced to 80% ad libutum consumption. Total feed and feces were measured on the last six days of the period. 1 - Van Waters & Rogers Ltd., 3256 McCallum Rd., P.O. Box 172, Abbots ford, B.C., V2S 4N8 99 Feed, ores and feces were sampled for chemical analyses as outlined in Chapter 8.2.3. The apparent dry matter, and apparent acid detergent fiber digestibilities of the hay with their standard errors were determined previously to be 53.16% ± 1.20, and 43.59% ± 1.27. The digestibilities of the PFW silages were found by calculating the difference between the digestibilities of the rations as fed, and the digestibility of the hay constant using the method of weighted means. Statistical analyses of the data was as described in Chapter 8.2.5, except that treatment and period effects were removed as sources of error. The data pertaining to one of the sheep on the 5.5% whey ration during Period 2 was omitted from the statistical analyses due to i t s extreme variation from the means. 9.3 RESULTS Table 9.2 shows the chemical composition of the PG PFW and the whey used in the silages, and hay used in the formulation of the complete rations. The PG PFW was high in fiber (NDF = 94.57%; ADF = 88.62%), low in SCHO (0.28%) and low in CP ( <0.63%). The condensed Cheddar cheese whey had a DM content of 29.0% and a relatively high pH (5.99). On a dry matter basis, the whey was high in ash (7.83%) and high in SCHO (48.09%). Figure 9.1 shows the daily temperatures of the different treatments. Although the 10.8% whey silage tended to have higher temperatures at the start of the fermentation period, generally the silage temperatures reflected the ambient temperature. The 0% whey silage showed a slight increase in temperature at the end of the monitored period. The minimum temperatures of the silages ranged from 4.5°C on Day 19 in the 0% whey 100 0 0 0 ( 0 ^ t C M O O O ( O T f C M O CM T- T- r- i - i -Figure 9.1 Average daily silages temperatures of barley-urea Prince George pulp mill fiber waste silages ensiled different levels of whey (each point represents the mean temperature of the temperature from two different locations within the silo, taken at two different times of the day) 101 Table 9.2 Chemical composition of ingredients (on a dry matter basis) used in Prince George pulp mill waste (PG PFW) barley-whey-urea silages and in the complete rations fed to ewe sheep INGREDIENT %DM1 %ASH %NDF %ADF %SCHO %CP %ADL pH PG PFW 26.93 2. 70 94.57 88.62 0.28 <0.63 4.72 7.76 WHEY 29.0 7. 82 _4 - 48.09 18.34 - 5.99 HAY/PFJI iRTS2 93.6 10. 06 51.00 40.53 4.35 18.86 — 1 - DM = dry matter; NDF = neutral detergent fiber; ADF = acid detergent fiber; SCHO = water soluble carbohydrates; CP = crude protein; ADL = acid detergent lignin 2 - mixed with PFW silages to form ration as fed 3 - values represent a single camposited sample analyzed in duplicate 4 - not analyzed Table 9.3 Chemical composition of pulp mill waste silage effluent SILAGE AMT1 %DM2 pH ASH3 %SCH03 %CP3 0% WHEY 22.84 2.89 8.22 35.46 0.78 21.28 2.7% WHEY 76.9 1.15 4.58 10.71 1.88 33.62 5.5% WHEY 48.7 2.73 4.66 _5 - -10.8% WHEY 62.0 1.16 7.40 38.19 0 12.18 1 - AMT = amount of effluent (kg) emitted by a single silo: DM = dry matter; SCHO = water soluble carbohydrates; CP = crude protein 2 - determined by weight difference before and after freeze-drying 3 - values are expressed on a dry matter basis 4 - values represent a single composited sample analyzed in duplicate 5 - not analyzed treatment, to 5.8°C on Day 23 in the 10.8% whey treatment. The maximum silage temperatures were recorded between Days 32-39, and ranged from 12.7°C in the 2.7% whey silage to 16.8°C in the 0% whey silage. Maximum and minimum air temperatures were 6.6° and 14.4°C. Table 9.3 shows the chemical composition of the effluent emitted by the silages during the fermentation period. The 0% whey silage produced the least effluent (22.8 kg) while the 2.7% whey silage produced the most (76.9 kg). For the 0% whey treatment, the majority of the effluent was collected between Days 2-10, while for the other silages the effluent continued to be produced throughout the entire 40 day fermentation period. The effluents 0% 102 were low in DM, and on a dry matter basis contained mainly CP and ash. The whey treatment had the highest pH (8.22) and the 2.7% whey treatment had the lowest pH (4.58). Table 9.4 shows that the 10.8% whey silage treatment had the highest concentration of VFAs (4776 nM/g), while the 0% whey silage had the lowest concentration of VFAs (42 nM/g) in the effluents measured. The main VFAs in the effluent were acetic and propionic acids. Of the measurable VFAs, in the condensed cheddar cheese whey, 99% was acetic acid and 1.00% was butyric acid. No VFAs were detected in the raw PG PFW. Table 9.4 Concentration (molar percentage) of volatile fatty acids in pulp mill silage effluent SILAGE ACET1 PROP IBUT BUT IVAL VAL TOTAL2 (%) (%) (%) (%) (%) (%) (HM/g) 0% WHEY 39.303 32.74 U4 27.96 U u 41.64 2 .7% WHEY 33.83 66.17 U U u u 1593.18 5 .5% WHEY 52.76 36.96 u 6.61 u 1.74 3376.88 10 .8% WHEY 35.50 62.30 u U u u 4776.48 1 - ACET = acetic acid; PROP = propionic acid; IBUT = isobutyric acid; BUT = butyric acid; IVAL = isovaleric acid; VAL = valeric acid 2 - TOTAL = cumulative total of a l l measured volatile fatty acids emitted per silo; values are corrected for the amount of effluent discharged by each silage 3 - values represent single samples analyzed in duplicate from single silos 4 - undetectable concentration Table 9.5 Chemical composition of pulp mill waste silages after ensiling (on a dry matter basis) SILAGE %BM1 %ASH %NDF %ADF %SCHO %CP %ADL pH GE 0% WHEY 22.82 1.84 76.70 69.94 0.34 5.69 3.66 5.15 4302 2.7% WHEY 26.5 2.01 76.52 71.28 0.56 6.56 4.49 4.76 4391 5.5% WHEY 24.6 2.51 74.06 68.24 0.83 7.31 3.65 4.80 4323 10.8% WHEY 28.0 2.94 69.63 64.69 2.29 8.00 3.49 4.43 4397 1 - BM = dry matter; NDF = neutral detergent fiber; ADF = acid detergent fiber; SCHO = water soluble carbohydrates; CP = crude protein; ADL = acid detergent lignin; GE = gross energy (kcal/g) 2 - values represent a single composited sample analyzed in duplicate 103 The chemical composition of silages after ensiling is shown in Table 9.5. The DM content was lowest in the 0% whey silage and highest in the 10.8% whey silage, ranging from 22.8-28.0%. Before ensiling these mixtures, the DM content was 33.3%. With increasing additions of whey, pH, NDF and ADF contents of the silages decreased. The pH dropped from 5.15 in the 0% whey silage to 4.43 in the 10.8% whey silage. The ash, SCHO and CP content increased with the addition of whey. The SCHO increased from 0.34% to 2.29%, and the CP increased from 5.69% to 8.00%. The gross energy (GE) values tended to be similar for the different silages and ranged from 4302-4397 kcal/g. The chemical composition of the four rations are shown in Table 9.6. The ash, CP and pH contents were similar for a l l treatments. The ash content was less than 8.15%, and the CP content ranged from 15.00-15.88%. The SCHO contents of the 5.5% and 10.8% whey treatments were significantly larger than the 0% and 2.7% whey treatments. In a l l rations, the SCHO content was less than 3% of the total dry matter. The NDF and ADF contents in the 0% whey treatments were significantly larger than in the 10.8% whey treatment. The NDF content of Table 9.6 Chemical composition (on dry matter basis) of Prince George barley-^whey pulp mill silage rations fed RATION %DM %ASH %NDF %ADF %SCH0 %CP PH 0% WHEY 46.9a 8.02a 64.05c 51.56b 1.57a 15.19a 5.08a 2.7% WHEY 55.9a 8.09a 59.24b 46.95a 2.01ab 15.06a 5.11a 5.5% WHEY 50.5a 7.83a 62.24bc 46.77a 2.29bc 15.00a 5.09a 10.8% WHEY 55.2a 8.14a 54.15a 45.16a 2.89c 15.88a 4.97a 1 - DM = dry matter; NDF = neutral detergent fiber; ADF = acid detergent fiber; SCHO = water soluble carbohydrates; CP = crude protein 2 - values are means of weekly composites during each feeding period; within a column, values with different letters differ significantly (P < 0.05). 104 Table 9.7 Voluntary intake (on a dry matter basis) of sheep fed PG PFW barley-whey-urea silages TREATMENT INTAKE (kg/D) INTAKE (kg/D) AVG INTAKE PERIOD 1 PERIOD 2 (kg/D) 0% WHEY 2.46 ± 0.241 2.42 ± 0.12 2.44a2± 0.15 2.7% WHEY 2.80 ± 0.30 1.92 ± 0.12 2.29a ± 0.17 5.5% WHEY 1.94 ± 0.24 1.99 ± 0.14 1.94a ± 0.17 10.8% WHEY 1.77 ± 0.30 1.83 ± 0.21 1.76a ± 0.22 AVERAGE 2.22a ± 0.12 2.00a ± 0.13 1 - values are the least squared means ± standard error of the mean 2 - within a given block, values with different letters differ significantly (P < 0.05) the rations ranged from 54.15% to 64.05%. The ADF content ranged from 45.16% to 51.56%. The voluntary intake of the sheep fed the PG PFW barley-whey-urea silages i s shown in Table 9.7. The average intakes of the treatments were similar in both periods for a l l rations except the 2.7% whey treatment. The average intake of the 2.7% whey ration dropped from 2.80 kg/D in Period 1 to 1.92 kg/D in Period 2. The average intake of both periods showed no significant treatment differences, although intakes tended to decline with the addition of whey. Table 9.8 shows no significant treatment difference in average daily gains (ADG) or apparent dry matter digestibilities of the rations (DMD). However, with both these parameters the effect of period was significant. ADG tended to decrease with the addition of whey. The DMD of a l l rations were similar and ranged from 59.26% in the 0% whey treatment to 61.84% in the 2.7% whey treatment. Both ADG and DMD were significantly lower in Period 2 versus Period 1. Table 9.9 shows the apparent silage dry matter digestibilities (SDMD), the apparent silage acid detergent fiber digestibilities (SADFD) and the apparent silage neutral detergent fiber digestibilities (SNDFD). For each 105 Table 9.8 Average daily gain (ADG) and apparent dry matter digestibilities (DMD) of test rations TREATMENT ADG DMD (kg/D) (%) 0% WHEY 0.38 al± 0.092 59.26 a + 0.98 2.7% WHEY 0.33 a ± 0.10 61.84 a + 1.08 5.5% WHEY 0.19 a ± 0.10 61.46 a + 1.08 10.8% WHEY -0.08 a ± 0.12 61.29 a + 1.40 PERIOD 1 0.33 a ± 0.07 62.00 a + 0.77 PERIOD 2 -0.08 b ± 0.07 59.92 b + 0.83 1 - within a given block, values with different letters differ significantly (P < 0.05) 2 - values are the least squared means ± standard error of the mean Table 9.9 Apparent digestibility of dry matter (SDMD) and acid detergent fiber (SADFD) of barley-whey-urea PFW silage TREATMENT ADJ SDMD SADFD SDMD (%)! (%) (%) 0% WHEY 73.50 73.50 a2 + 3 .26J 88.37 b + 4.85 2.7% WHEY 81.96 82.09 a + 3 .59 97.74 b + 5.35 5.5% WHEY 80.48 80.84 a ± 3 .59 89.91 b + 5.35 10.8% WHEY 79.44 80.25 a + 4 .66 72.46 a + 6.93 PERIOD 1 82.64 a + 2 .56 92.73 a + 3.80 PERIOD 2 75.70 b 2 .77 81.51 b + 4.13 1 - dry matter digestibility of silage corrected for the digestibility of the whey; the dry matter digestibility of the whey i s assumed to be 86.9% (Anderson, 1975). 2 - within a given block, values with different letters differ significantly (P < 0.05). 3 - values are the least squared means ± standard error of the mean. factor, the digestibility coefficients were lower in Period 2 than in Period 1. The SDMD tended to be higher with the 2.7% whey (82.09%) and lower for the 0% whey treatment (73.50%). The SADFD was the only measured parameter to show a significant treatment effect. The SADFD was significantly lower versus the treatments with smaller additions of whey. The NDF digestibilities of the PFW silage were calculated but were unusually low. Problems were experienced filtering the NDFs of the fecal samples. It is 106 possible that analytical complications between the method (Waldern, 1971) and sample occurred. NDF digestibilities are not reported. 9.4 DISCUSSION After opening the silos, silage samples were taken and subjectively evaluated for mold growth, color and odor. The most noticeable changes occurred in the control (0% whey) silage. The 0% whey silage had a thin layer of black mold covering approximately half the surface. No mold growth was evident in the other silages. The 0% whey silage was darker in color than the other silages or the raw PFW. The 2.7% and 5.5% whey silages showed no change in color. The 10.8% whey silage was yellowish brown in color compared to the greyish-brown color of the other silages. The 0% whey silage had the strongest and most unpleasant odor of the silages. This silage had a "rotten" hydrogen sulfide smell. The other silages had much more of an acetic acid, pungent odor. The 10.8% whey silage had the faintest odor of a l l silage treatments. Based on these observations, even the smallest additions of whey (2.8%) improved the fermentation characteristics of the PFW barley-urea silages. The temperatures of the different silages were not indicative of large differences between treatments (Figure 9.1). The silage temperatures appeared to follow the ambient temperatures. This may be due to the lack of fermentation, or to the poor insulation qualities of the PFW. The increased temperature in the 0% whey silage near the end of the fermentation period was probably the result of aerobic deterioration (ie. a hole in the bag) rather than from an increased fermentation rate. This would account for the poor fermentation characteristics of the 0% whey silage, i t s unpleasant odor and mold growth in comparison to the other silages, that the increased 107 The chemical composition of the effluents (Tables 9.3 and 9.4) indicated addition of condensed whey did not result in a direct loss of whey in the form of immediate run-off. The low pH, low DM content, SCHO content and proportions of VFAs in the effluent indicated that the effluent run-off was influenced by fermentation. Unlike the previous tria l s where liquid whey was used (Chapter 7.0 and 8.0), condensed whey was used in this experiment. Liquid whey contains 93-94% water. As a silage additive large volumes of liquid whey must be added. This volume of liquid whey can result in problems with both fermentation and physical handling problems (Allen et al., 1937). Condensed whey is more practical although more expensive as a silage additive. Butyric acid made up 28% of the VFAs detected in the 0% whey silage effluent. In the 5.5% whey silage, 6.6% of the VFAs in the effluent was butyric acid. If the VFAs in the effluent can be used as an indicator of the VFAs in the silage, there is a decrease in the formation of butyric acid with increased levels of whey. As well, the dominance of propionic acid in the effluent indicated that the silage microbes favored i t s production. If similar reactions occur in the rumen, propionic acid production supports the fact that PFW silage is a good energy source. Pulp mill residues were generally neutral or slightly alkaline (Table 9.2). The addition of whey promoted a decrease in the pH of the ensiled mixture indicating that some fermentation occurred (Table 9.5). Allen et al . (1937) showed that silages treated with whey had lower pHs (3.8) than untreated grass silages (4.2-5.2). Nevens and Kuhlman (1936) found that 1-5% dried whey effectively increased the acidity of alfalfa silage compared to that of the control. Dash et al. (1974a) effectively increased the lactic acid production, decreased the acetic acid production and reduced the 108 pH of the hay silages with the addition of 1 and 10% whey to chopped alfalfa hay. Also with the addition of whey, NDF content decreased (from 76.70% to 69.63%), and ADF content decreased (from 69.94% to 64.69%) (Table 9.5). The results of Dash et a l . (1974a) showed a similar decrease in in NDF and ADF with increasing levels of whey. This reduction in the fiber proportion may be due to the fermentation losses and conversions during ensiling, and/or due to the dilution factor of the higher whey addition (Dash et al. , 1974c). The CP in the silages (Table 9.5) was derived from the barley and whey. The differences in CP between silage treatments corresponded with increasing whey levels. The levels of CP in the silage indicated that the protein supplied by the whey to the mixture was not lost in the effluent. In addition, the protein content of dried whole whey is comparable to that of grain. The main protein in whey is lactalbumin, one of the highest quality naturally occurring proteins (Schingoethe, 1976). The gross energy content of the silages was approximately 4.3 kcal/g (Table 9.5). This was similar to the energy contents of the 0% and 2% whey treated alfalfa haylages which was also 4.3 kcal/g reported by Dash et a l . (1974c). This increase in gross energy from that reported for the PG PFW in Chapter 8.0 was primarily due to the high lactose content of whey (70-73% on a dry matter basis) (Scningoethe, 1976). The differences in the chemical composition of the PFW-whey silages (Table 9.5) was reflected in the composition of the rations (Table 9.6). The difference in NDF and ADF content between the treatments was evident in the rations. Even with the addition of hay to the ration, the SCHO content was s t i l l low ( < 3%). However, the alfalfa hay content increased the CP content of the ration. The lowest CP level in the rations was 15.00% of the total dry matter. This level was more than sufficient to meet the 109 requirements of nonlactating ewes during gestation as recommended by the NRC (1985). Although the decrease was not significant, the intake of the barley- • whey-urea PFW silage tended to decline with the addition of whey (from 2.44 kg/D to 1.76 kg/D) (Table 9.7). The exception to this trend was the intake of the 2.7% whey silage treatment in Period 1 which was greater (2.80 kg/D) than the 0% whey silage treatment (2.46 kg/D). The trend of depressed intakes with whey additions was contrary to previous findings which reported silages treated with whey were more acceptable than untreated hay silages or hay (Dash and Voelker, 1971; Dash et al., 1974a). Perhaps the depressed intakes of the whey silage treatments might have been due to aerobic deterioration or degradation of the rations prior to feeding. Anderson et al . (1974) showed that the palatability of whey was depressed with an increase in acid content. Whey kept over 36 hours at ambient temperatures was not consumed as readily by dairy cattle as fresh or 24 hour old whey (Anderson et al., 1974). Table 9.8 shows that the ADG on the whey treated silage rations tended to be lower than the control ration, although the differences were not significant. The decrease in ADG may be explained by the decreased intake (Table 9.7). Other studies reported increased live gain with beef cattle, dairy cows, heifers and lambs with the addition of 0.9%-6.2% whey in the diet or as a silage additive, although these gains were not always significant (Woods and Burrough, 1962; Larson et al . , 1963; Hendrix and KLopenstein, 1972); Dash et al., 1974c; Schingoethe et al . , 1975; Schingoethe and Breadsley, 1975). In some cases the increased weight gain was accompanied with increased intake (Woods and Burrough, 1962; Schingoethe and Breadsley, 1975). adjusted for the dry matter of the whey (Anderson, 110 The apparent dry matter digestibilities of the silages (SDMD) were 1975) as outlined by Schingoethe (1976) (Table 9.9). The adjusted SDMD was slightly lower than the SDMD calculated. This adjusted SDMD gives a better estimate of the effects of the additives during fermentation. The adjusted SDMD was 5.9%-8.5% greater than the untreated control silage (Table 9.9). Schingoethe (1976) showed a 4-15% increase in dry matter digestibility of silages treated with dried whey over that of the untreated control silages. Table 9.9 shows the neutral detergent fiber digestibilities (SNDFD) and the acid detergent fiber digestibilities (SADFD) of the silage. The SADFD tended to be higher in the 2.7% whey silage (97.74%) than in the control silage without whey (88.37%). Johnson et a l . (1962) explained^the improvement in the digestibilities of cellulose, hemicellulose, lignin, c e l l wall contents and ADF in whey treated silages by the improved lactic acid fermentation and the increased lactic acid content. Allen et a l . (1937) showed the fiber fractions to be more digestible in silages with 4.9-5.8% whey (80.6-83.3%) than in fresh grass (75.1%). Dash et a l . (1974c) also reported significant improvements (P < 0.01) in the apparent digestibilities of DM, GE, CP, ash, c e l l wall contents, ADF and cellulose in the 2% whey treated haylage compared to the untreated control. A similar response in apparent digestibilities of similar chemical constituents occurred when 1 and 10% whey was added to chopped alfalfa hay (Dash et al. , 1974a). The in vitro dry matter disappearance of sunflower silage with 2% whey was significantly higher (P < 0.005) than with 1% dried whey. The SADFD appeared to be highest with the 2.7% whey silage (97.74%), and lowest with the 10.8% whey silage (72.46%) (Table 9.9) although these differences were not significant. With levels of whey higher than 2.7%, the digestibility of the fibrous components in PFW silage decreased. These I l l trends agree with the results of Dash et al . (1974a) who showed that although the digestibilities were generally highest for the 10% whey treated hay silages, the cellulose digestibility was highest for the 1% whey treatment. Both readily available fermentable carbohydrates and viable lactic acid organisms are necessary for good silage fermentation with minimal losses in the original feeding value of the silage (Allen et al . , 1937; Dash et al., 1974a). Additives have been used to regulate the microbial activity for a desirable fermentation (Dash et al., 1974c). The use of whey as a silage additive ensures that lactobacilli predominant the fermentation, resulting in a high lactic acid content with minimum spoilage (Allen et al . , 1937 ; Dash et al., 1974c). In spite of the tendency for improvements in digestibility with the addition of whey, other than with SADFD, there were no significant treatment differences in any of the measured components. Nevens and Kuhlman (1936) added 1-5% dried whey to alfalfa silage. A l l silages, even the control, were of good quality. No difference in silage quality (aside from the acidity) between the control and treated silages were reported. The lack of statistical difference between the various whey treatments reported may be due to the following: 1.) In this experiment, "sweet" Cheddar cheese whey was used as an additive, as opposed to "acidic" cottage cheese whey. Much of the research that has previously been done failed to specify whether "sweet" Cheddar cheese whey or "acid" cottage cheese whey had been used. "Sweet" whey may not have had the same affect on the digestibility of the fiber components as "acid" whey. 112 2. ) Lactose in liquid whey may already have been fermented by the time the whey was added in the silage mixture (Huber, 1983). Lactose in the whey is converted by bacteria to lactic acid. Lactic acid was shown to be a good preservative (Allen et al., 1937). However, improvements in the digestibility of haylage were not as great as when dried whey was used (Allen et al. , 1937). However, fiber with whey i s likely more digestible than i f no additives were used (Allen et al., 1937). This is also supported by the fact that whey constituents other than lactose appeared to be responsible for the improved digestibilities of the haylages (Dash et al. , 1974a). 3. ) Possibly the addition of whey to the silage introduced a range of microflora which competed with one another. The microflora populations may have fluctuated greatly and may have been too diverse to utilize completely the substrates available (Allen et al., 1937). The inclusion of a large mixed microflora in the silage may develop in a way detrimental to the predominance of the lactic acid fermentation (Allen et al. , 1937). Thus, increasing whey levels would not show any improvements in digestibility. 4. ) If there was a lack of readily available carbohydrates in the silo, any further change in the digestibility of the ensiled substrate would not be possible. Although whey is an natural inoculum, i t can not influence the silage i f there is insufficient sugar to ferment (Woolford, 1984). Martin et a l . (1952) indicated that 3% dried whey in alfalfa silage had no significant effect on the top spoilage of silage, and that ground shelled corn was a more effective additive. This lack of improvement in the fermentation of the whey treated silage was probably due to the relatively small amount of readily available carbohydrates present (Schingoethe, 1976). 113 The in vitro dry matter disappearance of sunflower silage with 2% whey was significantly higher (P < 0.005) than with 1% dried whey. This improvement in the digestibility was greater than that which could be accounted for by the addition of the added whey. The low response at 1% was attributed to the lack of readily available carbohydrates (Sdiingoethe et al. , 1980). 5.) Further increases in digestibility would be impossible i f limiting factor was present, or i f the threshold for digestibility had been reached. In vitro digestibilities of 7 of 11 types of paper tested were improved the improvements in digestibility were not directly related to the amount of when the paper was soaked in whey (Becker et al., 1975). However, whey absorbed (Becker et al., 1975). Although no treatment effects were measurable, ADG, DMD, SDMD, SADFD and SNDFD a l l showed significant period effects. In each case the measured parameter was lower in Period 2 than in Period 1. This significant period effect accounted for the relatively large standard errors shown in Tables 9.8 and 9.9. There were no significant interactions between period and treatments. This period effect may be explained by the possibility of a carry-over effect. This possibility can not be overruled, since no positive hay control was included during the testing period. A carry-over effect would cause a decrease in digestibility with time i f the feed contained a chemical contaminant compound which could accumulate with time, this compound may have an adverse affect on digestibility. 114 The animals' health did not deteriorate over the two periods tested, nor was there a major change in the air temperature during the two testing periods which would account for a period effect. The only other identifiable difference between the two periods was the possibility of aerobic deterioration in the silages. The freezer where the silages were stored broke some time between the f i r s t and second periods. The silages thawed. The exposure to air temperatures for a prolonged period may have resulted in aerobic deterioration. Aerobic deterioration may have altered the acid content of the silages and may have affected the intake and digestibility of the silage. Lower intake of silage was associated with extensive degradation, low fermentation quality and extensive fermentation in silages with low pH (Wilkins et al., 1971). However, a decreased intake between Period 1 and Period 2 was evident only in the 2.7% whey treatment (Table 9.7). Thus, the period effect had to be due to some unexplainable systematic period effect. The PFW silage with 2.8% whey tended to have a higher DMD, SDMD, and SADFD than the other silages. Based on these trends, the conclusion of this study agrees with Schingoethe (1976) who recommended 1-2% dried whey as an optimum level of whey to silage. Dash et al . (1974a, 1974b) also noted improvements in silage with 1-10% dried whey. Dash et a l . (1974c) concluded that the fermentation characteristics of the 2% whey treated alfalfa haylage were superior to those of the untreated silage. The improvement in digestibility of DM and fiber components and over a l l silage quality with levels of whey higher than 2% was negligible, and did not warrant the high cost of drying the whey. 115 The addition of whey at ensiling usually resulted in a faster, more complete fermentation, and a better quality silage as indicated by a lower pH, higher lactic acid concentration and higher digestibility (Allen et al., 1937; Schingoethe, 1976). However, the disadvantages of the use of whey include: market price, processing costs (ie. condensing and drying), transportation costs, problems with keeping the whey fresh until use, acid resistant tanks for storage, sanitation, and management problems. Thus, these factors could outweigh the direct benefits of using whey as a silage additive for PFW especially when a dairy is not located near the producer and pulp mill. C H A P T E R T E N 116 1 0 . 0 A P R E L I M I N A R Y S U R V E Y O F T H E P A L A T A B I L I T Y O F E N S I L E D P U L P M I L L F I N E S A S D E T E R M I N E D B Y D A I R Y H E I F E R S 1 0 . 1 I N T R O D U C T I O N The major factor limiting production of silage-fed animals i s the level of voluntary consumption (Wilkins and Wilson, 1970). Dry matter intakes of silages may be approximately 70% of the intake of corresponding dried feeds (Wilkins and Wilson, 1970). Intake may be limited by breakdown products such as free acids, ammonia or clostridial fermentation and other secondary changes in the feed (Wilkins and Wilson, 1970). In Chapters 8.0 and 9.0, 20-23% ensiled PFWs, on a dry matter basis, in hay based rations were fed to sheep. Croy and Rode (1988) fed Hereford steers PFW mixed with timothy-clover silage in proportions as high as 48% PFW on a dry matter basis. However, the treatment of the PFW and the remaining ingredients in the ration fed may have affected intake levels. To maximize the benefits of a low cost, high energy feed, i t s contribution in the ration must be as large as possible without affecting intake or digestibility. In this study, 45% ensiled PFW mixed with a hay based ration was fed to dairy heifers to access palatability. 1 0 . 2 M A T E R I A L S A N D M E T H O D S PG PFW was ensiled with barley, whey and urea for 40 days (as outlined in Chapter 9.2). The proportions of the ingredients in the PFW silage rations are shown in Table 10.1. On a dry matter basis either 22.5% or 45% of the ration was ensiled PFW. Rations were mixed with the hay, frozen and thawed prior to feeding. These rations were fed successively to four 65-85 day old Holstein heifers. 117 Table 10.1 Dry matter proportions of ingredients in pulp mill fiber waste (PFW) silage rations fed to dairy heifers RATION DAYS FED PROPORTIONS OF INGREDIENTS 1 DAYS 5-14 30% PFW silage 28% crushed alfalfa pellets 42% short chopped hay 2 DAYS 14-17 60% PFW silage 40% short chopped hay During a five day adaptation period, the animals on a grain-based starter diet were gradually switched to the 30% PFW silage ration by increasing the amount of the latter by 25% per day. The animals continued to consume the 30% PFW silage ration for the next eight days. For the remaining four days the animals consumed the 60% PFW silage ration. A l l rations were fed on an ad libitum basis. Intake was recorded during the 12 day intake period. The average daily intakes were based on consumption during the f i r s t five days the 30% PFW silage was offered and the four days the 60% PFW silage was offered. The difference in intake between the two rations was tested by a t-test using the four animals as replicates. Average daily gain was based on the weight gain over the last seven days of the t r i a l . 10.3 RESULTS During the f i r s t 11 days of the feeding period the 30% PFW silage ration was readily consumed by the animals (Figure 10.1). Each day the amount offered was increased. On Days 12 and 13, the intake decreased. The 60% PFW silage ration was offered and consumed on Days 14 through 17. The average dry matter intake and standard error of the 30% PFW silage was 2.73 ±0.15 kg/D and with the 60% PFW silage was 3.99 ± 0.31 kg/D (Table 10.2). 118 r * . < o i o « t o o c N t - o Figure 10.1 Dry matter intakes of the 30% and 60% pulp fiber waste (PFW) silages consumed by 77-90 kg dairy heifers during a 17 day feeding period 119 Table 10.2 Average daily gain (ADG) and ad libitum intake of dairy heifers corisuming rations containing pulp fiber waste (PFW) silage ANIMAL AGE ADG INTAKE ON INTAKE ON (DAYS) (KG/D) 30% PFW SILAGE 60% PFW SILAGE 1 65 1 0.862 2.23 3.53 2 73 0.71 3.3 4.0 3 83 0.29 2.7 4.0 4 85 0.29 2.6 4.4 MEAN ± SEM4 77 ± 2.2 0.54 ± 0.07 2.7 ± 0.15 3.99 ± 0.31 1 - age of dairy heifers at begixfliing of survey 2 - ADG was based on the weight gain over the last 7 days on which intake was recorded 3 - intake (kg) is expressed on a dry matter basis; values shown are the average of the f i r s t 5 and 4 days the animals consumed the 30% PFW and 60% PFW silages respectively 4 - standard error of the mean The final weight of the animals on t r i a l was 86 ± 5 kg. The average daily gain ranged from 0.29 to 0.86 kg/D. 10.4 DISCUSSION The 60% PFW silage ration was drier than the 30% PFW silage ration (67.05% and 51.52% dry matter). Dry matter content of the forage at time of ensiling and the resulting fermentation processes, were important factors in determining the rate of consumption of the resulting silage (Thomas et a l . , 1961). A lowered intake may be a consequence of moisture content (Thomas et al. , 1961), or appetite depressants such as organic acids and products of protein degradation which were relatively more abundant in low DM silages (Neumark et a l . 1964). The texture of the 60% PFW silage ration was also much coarser, and the overall consistency more uniform than the 30% PFW silage ration. The difference in the uniformity of the rations may have been due to the presence of crushed alfalfa pellets in the 30% PFW silage ration which were lacking in the 60% PFW silage ration. To avoid confounding the experiment, the remaining portion of both rations should have been short chopped hay. 120 However, the availability of the feed made this impossible. The odor of the 60% PFW silage ration was less strong, less pungent and somewhat sweeter than the 30% PFW silage ration. Possibly aerobic deterioration in the 30% PFW silage ration made i t less acceptable than the 60% PFW silage. Bacterial degradation, rather than a problem with the actual nature of the feed, would account for the decline in intake over time on the 30% silage. The 30% PFW silage ration had been frozen and thawed numerous times prior to feeding, and had been exposed to the a i r temperatures for longer periods of time. The 60% PFW silage ration had been frozen once and then was consumed over a shorter time frame. The latter ration had less time to deteriorate. However, Croy and Rode (1988) showed a significant linear decrease in voluntary intake as the proportion of PFW in the ration increased from 0-48%. No statistical comparisons were made between levels because of the number of confounding factors and small sample size. Also, the two rations were fed during two different time periods. Comparisons of intake between the two rations was difficult since period effects could not be eliminated as a source of variation. The maximum intake of the 60% PFW silage ration was not measured due to the lack of feed and the short feeding period (Days 14-17). The dry matter intakes of the heifers fed the 30% and 60% PFW silage rations were weight, comparable to that outlined by the NAS-NRC (1976) for animals of similar sex and The average daily gain was normal for animals of similar breed, age and The dairy heifers which were used in this t r i a l were very young. Whether or not the animals had totally functional rumens is questionable. Heifers also tend to be less selective than older cows. For relatively short periods of time, dairy heifers accepted 60% PFW silage or 45% ensiled PFW in hay based rations at levels without problems. From the data presented, recxsmmendations on the optimal level of ensiled PFW in the ration for maximum intake and acceptance of PFW over extended periods of time are dif f i c u l t to predict. However, based on these observations, beef cattle should accept levels as high as 45% ensiled PFW in rations. CHAPTER ELEVEN 122 11.0 EVALUATION OF PULP MILL FIBER WASTE AS A FEEDSTUFF FOR BEEF CATTLE 11.1 INTRODUCTION Cellulosic PFWs are easily blended into rations. Animals have consumed diets up to 75% pulp (a product similar in chemical composition) with acceptable digestibilities (NRC, 1983 and Baker et a l . , 1975). Croy and Rode (1985) fed PEW with timothy-clover silage to Hereford steers, and, based on dry matter digestibility, showed that the optimum level of PFW in the ration was 48% compared to lower levels. At this level, palatability of the complete ration was not affected (Croy and Rode, 1985). However, the optimum level of ensiled PFW when mixed with a forage/grain based ration may vary, and affect both digestibility and palatability of the ensiled PFW. In this study, two different PFWs at two levels were mixed with a forage/grain ration and fed to Hereford-cross long yearling steers. Digestibility coefficients of the PFW silages were estimated with beef steers using acid insoluble ash as an internal marker. Digestibility coeffients, ad libutum intake (FI), average daily gain (ADG), and feed conversion (F/G) were used to assess the suitability of PFW as a feedstuff for animal production. 11.2 MATERIALS AND METHODS 11.2.1 EXPERIMENTAL DESIGN AND STATISTICAL ANALYSES This experiment included one positive control and four test groups. Each treatment was fed to three pens with three animals in each pen. A total of 45 experimental animals were used. The control group was fed a ration containing 80% barley and 20% hay. The test animals were fed either 123 ensiled PG PFW or K PFW at either 22.2% or 44.4% of the total dry matter. These rations are referred to as "PG22", "PG44", "K22" and "K44". Comparisons between the control and the four treatments were tested in a completely randomized design (CRD). Differences in PFW sources and PFW feeding levels were tested in a 2*2 factorial arrangement within the CRD. The Statistical Analysis System (SAS, 1985) general linear model (GLM) procedure was used to perform analysis of variance on the data. The GLM PDIFF least significant difference option determined the differences between the least squares means. In the case of ADG, animals were considered to be blocks, and in the case of FI and F/G, pens were the blocks. One animal was removed from a control pen due to bloating tendencies. One observation was missing in the statistical analyses. 11.2.2 SILAGE PREPARATION PFWs were obtained in July 1987. The PFWs were chopped with a forage harvester i operated by a 65 horsepower tractor. The PFW was mixed, on a dry matter basis, with 20% barley, 2.5% partially condensed acid whey (dry matter = 30.31%) and 1% urea. Each mixture was ensiled in an Ag Bag2 (plastic cylindar casing, diameter = 1.8 m). The K PFW and PG PFW mixtures were packed at 1000 and 300 psi respectively. The day after sealing the bags, trapped gas in the bags was released. The two silos then remained sealed for 81 days. Two temperature probes were placed in each of the silos. Silage core temperatures from two positions within the silo were recorded at 0900 and 1500 hours daily during the ensiling period. 11.2.3 EXPERIMENTAL ANIMALS The average i n i t i a l weight of the long yearling Hereford-cross beef 1 - John Deere 35 2 - "Ag Bag", Ag Bag Corp., Box 428, Astoria, Oregon, USA, 97103 124 steers was 372 ± 22 kg. Based on the animals' weights on two consecutive days, the animals were randomly assigned from weight outcome groups to the pens. The total animal weights for each of the pens and treatments were equal. The experiment was conducted in the beef cattle finishing barn at South Campus, U.B.C., Vancouver. Animals were shipped from Merritt, B.C. to Vancouver, B.C.. Upon arrival, the animals were given 2-3 days to adapt to the pens, feeders and waterers. During the f i r s t 10 days of the 28 day preadaptation period a hay diet supplemented with Aureo S-700 Beef Cattle Premix Vitamin Crumbles (Cyanamid]_) mixed with barley was fed. During this preadaptation period the amount of grain in the rations was gradually increased. Animals were ear tagged, vaccinated with Triangle-3 (Fort Dodge Lab.2) and Covexin-8 (Cooper^), dewormed with Exhelm E (Rogar4), and deloused with Co-Ral (Cutter Animal Healths) • The animals were also treated with injectable vitamin A,D,E (Rogar^ and implanted with Synovex-S (Syntex Lab.g). Animals were weighed weekly throughout the feeding period. 11.2.4 TEST RATIONS The feeding period consisted of a 28 day preadaptation period, a 14 day adaptation period, and a 63 day testing period. PFW silage rations were prepared daily and were formulated to meet the NRC-NAS (1984) requirements for beef cattle. The rations are shown in Table 11.1. The canola-barley 1 - Cyanamid Canada Inc., Toronto, Ont., Canada, M2J 4Y5 2 - Fort Dodge Lab., 800 5th St. NW, Fort Dodge, Iowa, USA, 50501 3 - Coopers Agropharm Inc., Ajax, Ont., Canada, LIS 3B9 4 - Rogar, 17300 TransCanada Hwy., Kirkland, P.Q., Canada, H9J 2M5 5 - Cutter Animal Health, Bay Vet Division, Rexdale, Ont., Canada, M9W 1G6 6 - Syntex Lab. Inc., Pala Alta, CA, USA 125 ratio was adjusted so a l l rations had a minimum of 11.4% crude protein. The Ca:P ratios in the rations were adjusted with limestone. Otter Dairy Premix (Van Waters & Rogers^) supplemented the rations. A l l animals had free access to both water and cobalt iodized salt blocks. Rations were sampled daily. Weekly feed samples were composited, the PFW and the PFW silages were analyzed for DM, ash, pH, ADF, NDF, SCHO, lignin (Chapter 7.2), VFAs (Appendix A) and CP (Chapter 8.2). PFW silages were analyzed for calcium by the method of Heckman (1967) and phosphorus according to the Analysis of Agricultural Materials (1973). Table 11.1 Proportions on a dry matter basis of ingredients in rations fed to beef steers INGRFJDIENTS: CONTROL PG221 PG44 K22 K44 PG PFW SILAGE 2 0 30. 00 60. 00 0 0 K PFW SILAGE 2 0 0 0 30.00 60. 00 HAY 20. 00 10. 00 10. 00 10.00 10. 00 BARLEY 80. 00 46. 52 3. 92 46.30 3. 47 CANOIA 0 13. 48 26. 08 13.70 26. 53 LIMESTONE 2. 06 2. 13 1. 71 1.96 1. 39 1 - PG22 = 22% of ration was Prince George pulp mill fiber waste; PG44 = 44% of ration was Prince George pulp mill fiber waste; K22 = 22% of ration was Kamloops pulp mill fiber waste; K44 = 44% of ration was Kamloops pulp mill fiber waste 2 - PG PFW = Prince George pulp mill fiber waste silage; K PFW = Kamloops pulp mill fiber waste silage 11.2.5 DIGESTIBILITY COEFFICIENTS OF THE TEST RATIONS Three animals from each of the control, PG22, PG44, K22 and K44 groups were randomly selected to measure the digestibility of the test rations. One animal from each of the three pens was assigned to each treatment was used. Fecal grab samples were taken at 0800 hours for 7 days beginning on day 53 of the test period. During this collection period, feed and orts 1 - Van Waters & Rogers Ltd., 3256 McCallum Rd., P.O. Box 172, Abbotsford, B.C., V2S 4N8 126 (uneaten feed) samples were also taken. Daily feed, orts and fecal samples were weighed, composited and analyzed for acid insoluble ash (AIA) using the 2N HCI procedure according to Van Keulen and Young (1977). 11.3 RESULTS Figure 11.1 shows the daily temperatures of the PFW silages. Over the 81 day ensiling period. The maximum and iruxtimum daily temperatures for the K PFW and PG PFW silages were respectively 40.7°C on Day 15 and 24.3°C on Day 81, and 33°C on Day 1 and 16.8°C on Days 77-80. Like the PFW silages in Chapters 9.0, the silage temperatures (Figure 11.1) did not peak with time. Rather, the silage temperatures tended to decline with time. The lowest silage temperatures occurred at the end of the 81 day period. The K PFW silage seemed to have higher temperatures than the ambient and PG PFW temperatures, and higher tenperatures than those reported with similar silage mixtures in previous tr i a l s (Tables 7.3 and 8.3). Table 11.2 shows the chemical analyses of the PFWs. The majority of PFWs was cellulose. The PG PFW and the K PFW respectively had 82.88% and 73.16% cellulose. The difference in the cellulose fraction reflected the lignin and ash proportions in the two types of PFW. PG PFW had 3.17% lignin and 4.34% ash while the corresponding values were much larger in the Table 11.2 Dry matter composition (%) of Prince George and Kamloops pulp mill fiber wastes NUTRITIVE PULP MILL FIBER WASTES COMPONENT PRINCE GEORGE KAMLOOPS CELLULOSE 82.881 73. 16 HEMTCFTJITLOSE 6.59 6. 53 LIGNIN 3.17 5. 94 ASH 4.34 10. 07 %CP 1.00 0. 50 WATER SOLUBLE CARBOHYDRATES 0.44 0. 39 OTHER 1.58 3. 41 1 - values represent single samples analyzed in duplicate. 127 Figure 11.1 Air, Prince George pulp mill waste silage (PG PFW silage), Kamloops pulp mill waste silage (K PFW silage) tenperatures taken over a 80 day period. (Each data point represents the daily mean of two points within each silage bag). 128 Table 11.3 Composition of the Prince George pulp mill waste (PG PFW) and Kamloops pulp mill waste (K PFW) mixtures before and after ensiling (on a dry matter basis). %DM1 %ASH pH %ADF %HEMI %SCHO %CP %ADL %VFA before ensiling: PG PFW mixture 36.972'3 3.89 7.57 77.90 12.89 0.31 2.22 2.86 0.08 K PFW mixture 37.Ol2 10.12 9.36 75.37 7.77 0.36 2.72 5.53 0.20 after ensiling: PG PFW silage 26.39 4.473 4.58 78.73 6.53 0.47 3.31 2.81 7.18 K PFW silage 32.74 6.573 5.07 81.10 5.56 0.00 3.13 4.16 4.10 1 - DM = dry matter; ADF = acid detergent fiber; HEMI = hemicellulose; SCHO = soluble carbohydrates; CP = crude protein; ADL = acid detergent lignin; VFA = total volatile fatty acids 2 - mathematical estimation. A l l other values represent a composite of grab samples analyzed in duplicate 3 - values corrected for volatile fatty acids losses after drying Table 11.4 Concentration of individual volatile fatty acids in the Prince George and Kamloops pulp mill waste silages ACETIC PROPIONIC BUTYRIC VALERIC ISOVALERIC ISOBUTYRIC TOTAL PG PFW SILAGE 2.811'2 0.33 3.98 0.06 ND3 ND 7.18 K PFW SILAGE 0.80 0.24 2.67 0.36 0.03 ND 4.10 1 - Values are expressed as percentage of the total dry matter 2 - Values represent the mean of duplicate samples, prepared in duplicate and analyzed in duplicate 3 - not detectable Kamloops PFW with 5.94% lignin and 10.07% ash. Hemicellulose made up respectively 6.59% and 6.53% of the dry matter of the PG and K PFWs. The remaining fractions contained less than 1% soluble carbohydrates and less than 1% crude protein. Table 11.3 .shows the chemical composition of the PFW mixtures before and after ensiling. The pH of the PG and K PFW silages mixtures dropped from 7.57 and 9.36 respectively before ensiling to 4.58 and 5.07 after ensiling. Ensiling also resulted in a relatively large production of VFAs from an i n i t i a l proportion of less than 1% to 7.18% and 4.58% of the total dry 129 matter in the PG and K PFW silages. The other nutritive components showed a slight increase after ensiling. As discussed in Chapter 7.4, underestimating dry matter due to the loss of unmeasured volatile gases may have caused the remaining components to be overestimated. Also the inconsistencies in ash values before and after ensiling may have indicated errors in sampling (Table 11.3). Table 11.4 shows the concentration of the individual VFAs in the PFW silages. In the case of the PG PFW silage the majority of the 7.18% total dry matter was acetic and butyric acids which made up respectively 2.81% and 3.98% of the total dry matter. In the K PFW silage, VFAs made up 4.10% of the total dry matter. Butyric acid made up 2.67% and acetic acid 0.80% of the total dry matter in the K PFW. Table 11.5 shows the dry matter compositions of the test rations. In the PFW rations, ash values ranged from 5.87-8.22%. Ash values tended to be lower in the control ration (4.56%). Within the PFW rations, the ADF content ranged from 43.87-60.97%. ADF appeared to be lowest in the control (14.76%). Hemicellulose tended to be highest in the control (25.75%) and lowest in the 44% PFW rations (PG44 = 6.60%; K44 = 7.72%). SCHO content tended to be similar in a l l rations. SCHO content ranged from 3.05% in the K44 ration to 4.05% in the control ration. Table 11.5 Dry matter composition of test rations RATION %ASH %ADF1 %HEMI %SCHO %CP %OTHER CONTROL 4.562 14.76 25.75 4.05 12.25 12.33 PG22 PG44 5.87 6.88 43.87 59.00 20.70 6.60 3.61 3.13 11.44 12.06 14.51 12.33 K22 K44 6.73 8.22 44.75 60.97 13.21 7.72 3.24 3.05 12.88 14.13 19.19 5.91 1 - ADF = acid detergent fiber; HEMI = hemicellulose; SCHO = water soluble carbohydrates; CP = crude protein. 2 - Values represent duplicated samples from a composite of daily samples taken over the 7 week feeding period. 130 Table 11.6 Total dry matter digestibility coefficients of test rations. RATION %AIA1 IN FEED DIGESTIBILITY CONTROL 1.06 82.30 c 2 ± 0.383'4 PG22 1.85 82.38 C ± 2.51 PG44 2.41 80.31 be ± 0.97 K22 2.36 77.38 ab ± 2.45 K44 3.20 76.30 a ± 1.47 standard error of the mean 0.96 PG PFW silages 81.345a K PFW silages 76.84 b standard error of the mean 0.71 22.2% PFW in ration 79.886a 44.4% PFW in ration 78.30 a standard error of the mean 0.71 1 - AIA = acid insoluble ash 2 - within a block, values with different letters differ significantly different (P < 0.05). 3 - Mean values based on composited daily feed and fecal samples were from 3 animals over a 7 day period. Samples were analyzed in duplicate. 4 - digestibility values were calculated from AIA in feed and feces (as shown in Appendix B). Assumed recovery = 74.56% (derived from sheep fed a PG barley-whey-urea silage with alfalfa hay) 5 - mean value of rations fed at 22.2% and 44.4% pulp fiber waste 6 - mean value of Prince George and Kamloops pulp fiber waste silages. Table 11.7 Average daily gain (ADG), ad libutum dry matter intake (FI) and feed conversion (F/G) of beef steers during 63 days RATION ADG (kg/D) FI (kg/D) F/G CONTROL 1.9 a x± 0.092 11.1 a ± 0.3 5.4 a ± 0.4 PG22 1.8 a ± 0.08 10.9 a ± 0.2 6.1 a ± 0.3 K22 1.7 b ± 0.08 10.3 a ± 0.2 6.2 a ± 0.3 PG44 1.6 b ± 0.08 10.4 a ± 0.2 6.5 a ± 0.3 K44 1.5 b ± 0.08 9.8 a ± 0.2 6.8 a ± 0.3 PG PFW RATIONS 1.7 a ± 0.06 10.6 a ± 0.2 6.3 a ± 0.2 K PFW RATIONS 1.6 a ± 0.06 10.1 a ± 0.2 6.5 a ± 0.2 22% PFW RATIONS 1.7 a ± 0.05 10.6 a ± 0.2 6.1 a ± 0.2 44% PFW RATIONS 1.5 b ± 0.05 10.1 a ± 0.2 6.6 a ± 0.2 1 - means within blocks with different letters differ significantly (P < 0.05) 2 - least squares means ± standard error of the mean. 131 CP in the rations ranged from 11.44% to 14.13%. The "other" fraction contained mostly starches, lactic acid and fats. This fraction ranged from 5.91% in the K44 ration to 19.19% in the ¥22 ration. Table 11.6 summarizes the dry matter digestibilities of the test rations. Dry matter digestibilities ranged from 76.30% in the K44 ration to 82.38% in the PG22 ration. The digestibility of the control ration did not differ significantly from the PG PFW silages, but was significantly higher than both the K PFW silages. The overall average of the PG PFW silage at 81.34% was significantly higher than the K PFW silage at 76.84%. No significant difference between the digestibilities of the 22% and 44% PFW rations was detected. Table 11.7 shows the ad libitum dry matter intakes ranged from 11.0 kg/head/day in the control animals to 9.8 kg/head/day in the animals fed K44. Intake did not differ (P <0.05) between the control and any of the treatment groups, between PFW silages, or between PFW levels in the rations. Table 11.7 also shows feed conversion of the steers over the 63 day testing period. The K44 group tended to have the poorest feed conversion (6.8), while the grain fed control animals tended to have the best feed conversion (5.5). However, this difference was not significant. No significant differences in feed conversion between controls and treatment groups, PFW silages, or between levels of PFW in the rations were detected. Table 11.7 shows ADG ranged from 1.5 to 1.9 kg/day. The ADGs of the control and PG22 treatments were significantly higher than the other treatment groups. ADG did not differ significantly between the PG and K PFW silages, but was significantly higher with the 22% feeding level compared with the 44% level. 132 Table 11.8 Average weekly weights (kg) and standard deviations of beef steers fed control and rations containing pulp fiber waste silage WEEK CONTROL1 PG22 PG44 K22 K44 ADJUSTMENT PERIOD: 1 374 + 23 372 + 23 371 + 13 371 + 34 371 + 34 2 397 + 24 382 + 29 382 + 14 379 + 14 387 + 34 TEST PERIOD: 3 404 + 29 408 + 29 411 + 14 399 + 21 415 + 36 4 423 + 36 425 + 30 420 + 15 420 + 20 429 + 36 5 427 + 33 435 + 30 425 + 13 434 + 20 439 + 37 6 445 + 37 449 + 29 444 + 15 443 + 21 449 + 40 7 462 + 35 457 + 30 455 + 15 455 + 22 458 + 40 8 472 + 38 473 + 32 464 + 16 466 + 23 472 + 43 9 486 + 33 483 + 32 470 + 18 474 + 25 476 + 43 10 492 + 41 499 + 32 486 + 17 490 22 488 + 42 11 506 + 45 511 + 34 495 + 22 493 + 25 499 + 44 12 518 ± 44 522 + 31 512 + 23 505 + 24 507 + 47 1 - each treatment group has 9 animals. Table 11.9 Linear models and coefficient of determination (r 2) for average animal weights for a control ration and rations containing pulp mill waste silages during a 63 day feeding period. RATION REGRESSION LINE r 2 CONTROL Y = 396. 97 + 12. ,57x 1 0. 997 PG22 y = 396. 97 + 12. ,58x 0. 997 PG44 y = 397. 67 + 11. ,01X 0. 991 K22 y = 408. 15 + 10. .02X 0. 996 K44 y = 396. 44 + 11. ,20x 0. 986 1 - refer to Table 11.8 for average weekly animal weights and standard deviations. Table 11.8 and Figure 11.2 show the average weekly animal weights over the nine week feeding period. There were no dramatic increases or declines in body weight. Weight gains were linear and constant with time (Figure 11.2). The regression lines for weight weight gain are shown in Table 11.9. The r-squared values of these equations approach 1.0. This indicated that almost a l l variation in average animal weights can be explained by the independent variable, time. 133 O I O O I O O I O O I O O • O C M O K l O C M O h - l O Figure 11.2 Average weekly weights of long yearling beef steers over a twelve week feeding period on control and pulp mill fiber waste silage rations (refer to Table 11.8 for treatment weekly averages and standard deviations) 134 11 . 4 DISCUSSION When the silage bags were opened, the K PFW silage had thick, like mold covering the face, and black mold along the sides. The mold was 10-15 cm deep in places. The mold in the PG PFW silage was not as concentrated in distinct patches as was the case in the K PFW silage. The mold in the PG PFW silage tended to be sprinkled throughout the silo. The odor of the PFW silages were slightly pungent while faintly retaining the distinctive smell of the pulp mill. In a few places, the K PFW silages had "hot spots" where the material appeared to be burning. Poor compaction of too dry a material, improper handling or inadequate sealing may cause excessive heating of ensiled material (Huber and Kung, 1981). Generally, very dry crops are more diffi c u l t to consolidate and have higher air:herbage ratios. However, in this case, because of the moisture contents of the PG PFW and its consistency, the PG PFW silage was packed at a lower pressure than the K PFW silage. Heat damaged forages result in an increase in acid detergent insoluble nitrogen, less available protein and energy for microbial and host needs (Huber and Kung, 1981), thereby decreasing the overall digestibility of the material (McDonald, 1981). The PG PFW silage did not have any "hot spots". However, there was noticeably more mold growth. The PG PFW silage bag sat on a slope. With time, liquid from the silage mixture drained toward the lower side and collected. The PFW silage in these places was saturated with the liquid and had a noticeable color change from brownish grey to a yellowish brown. The PG and K PFW silages produced respectively 3.98% and 2.67% of the total dry matter as butyric acid. The molar proportions of acetic:butyric acids in the PG PFW silage and in the K PFW silage were respectively 48.19:46.54, and 26.09:56.92. Butyric acid is suggestive of clostridial fermentation. The 135 weak acidic and wet conditions, as well as silage temperatures in the mid-thirties to low forties favored Clostridia growth. Clostridia destroy lactic acid. This results in a rise in pH and generally a poorer preservation. For hays and grasses, digestibility is inversely proportional to the ADF content of the substrate. A high ADF would normally be associated with a relatively high proportion of lignin, and consequently the substrate would have a poor digestibility. In this study, the control rations had a low ADF and high hemicellulose content compared to that of the PFW rations (Table 11.5). The hemicellulose, starches and other easily digestible carbohydrates accounted for the high digestibility of the control ration (Table 11.6). However, the PFW rations had very high proportions of ADF with very l i t t l e associated lignin compared to that of the control. Thus the high dry matter digestibilities of the PFW rations (Table 11.6) would be expected, given the large proportion and the high availability of cellulose in the experimental rations. Generally, digestibility is inversely related to lignin content for wood pulps, chemically treated wood and paper (Mertens and Van Soest, 1971). Both in vitro and in vivo t r i a l s have shown that paper products and fibrous pulp wastes were highly digestible (Mertens et al., 1971; Mertens and Van Soest, 1971; Croy and Rode 1988). Table 11.6 also shows that PG PFW silage was significantly more digestible than K PFW silage. The chemical composition of the PFWs (Table 11.2) and resulting the silages (Table 11.3) may account for this difference in digestibility. PG PFW had less lignin and ash than the K PFW. Animals on the PFW were more quickly adapted to f u l l feed than the grain fed animals during the adaptation period. The "start" of the feeding period was adjusted so a l l animals were on full-feed. Initially same sorting 136 occurred, but with time ad libutum intake increased and sorting tended to be minimal. Average ad libutum intake as expressed as a proportion of body weight ranged from 2.23% in the K44 ration to 2.49% in the control group. NDF is usually inversely proportional to intake. This accounts for the high intake of the control ration where the NDF value was relatively low (Table 11.7). However, this generality can not be applied to the PFW fed animals. Above 65% digestibility, bulk no longer controls the intake of forages (Pigden and Bender, 1972), resulting in relatively high intakes of the animals on the test rations. Although the animals fed the K PFW rations tended to have lower intakes than the PG PFW rations (10.1 kg/D; 10.6 kg/D) (Table 11.7). The difference was not significant. The higher butyrate to acetate ratio in the K PFW compared to the PG PFW silage (Table 11.4) may partially account for the depressed intakes of the K PFW rations compared to that of the PG PFW rations. When Clarke and Dyer (1973) fed sulfite processed Douglas f i r to Hereford steers, the lower dry matter intake of the 70% wood-fed group was attributed to the high moisture content (68%) and reduced digestibility of the ration which caused a greater rumen f i l l , and lower rate of passage. Over the two week adaptation period and the ten week feeding period, the animals gained an average of 141 kg (Table 11.8). The control and PG22 fed animals had higher ADGs than the other treatments (Table 11.7). The difference was probably due to the slightly higher intakes (Table 11.7), and the slightly higher ration digestibilities (Table 11.6) of the control and PG22 rations. This difference in ADG was not large enough to cause a significant difference in feed conversion. Figure 11.3 summarizes intake, ADG and feed conversion. Feed conversion is plotted above the x-axis. The difference Figure 11.3 Conparison of feed conversion (feed/gain) between treatment groups, and the differences in average daily gain (ADG) and ad libitum intake between the control and pulp mill fiber waste rations fed to Hereford-cross long yearling beef steers 138 between the control and treatment groups for intake and ADG i s graphed below the x-axis. The animals fed PFW tended to consume less feed and correspondingly gained less weight. Feed conversion is a ratio between intake and gain. Since both intake and gain dropped compared to the control, the ratio, feed conversion, was unaffected. The tendency of feed intake to decline, and digestibility to decrease between the test rations, resulted in a corresponding significant difference in ADG between treatments. However, in a l l cases, the average daily gains shown by the treatment groups were respectable (Table 11.8). Dinius and Bond (1975) fed 264 kg Angus beef heifers a diet of 50% unbleached hardwood pulp fines from a sulfite mill over a 99 day period. These animals had higher average daily gains than the control orchardgrass fed group (0.74 kg and 0.47 kg respectively). However, when Dinius and Bond fed nine beef heifers a ration containing 75.1% PFW for 209 days, the animals showed no difference in weight gain. In this latter case, the intake was 3.21% and 2.81% of their body weight for the PFW and hay fed animals respectively. However, feed conversion was poorer in the PFW fed animals versus the control animals (16.99 and 12.93). In our study the intakes were higher and feed conversion better than in Dinius and Bond's study. One possible explanation for this difference in feed conversion was that the pregnant animals in Dinius and Bond's study so very l i t t l e of the digestible energy in the feed would be used for growth. The growing animals used in this study would have better feed conversion ratios in comparison. The results in this study agree with findings reported by Clark et a l . (1971) who fed Douglas f i r wood pulp to 24 332 kg Hereford steers for 70 days. Intake (kg), ADG (kg) and feed conversion for a control fed group (82.5% barley), a group fed 50% wood pulp, and a group fed 70% wood pulp were respectively 8.73, 1.75, 5.30; 9.40, 1.44. 7.15; 7.86, 1.36, 5.76. 139 The range in ADG in cur study was slightly higher (1.5-1.9 kg) than in Clark's study. This difference may be due to the higher intakes reported in this study compared to Clark's. The palatability of other ingredients in the rations rather than the palatability of the differing PFWs alone may have affected the intakes. This study did not include animal carcass data since the animals were switched to a hay diet prior to slaughter. However, at the end of the 63 days most animals were close to market weight and had appropriate finishes. The carcasses of the control animals in Clark's study graded "choice" while the pulp fed animals graded "high good". A study on wether lambs by Riquelme et al. (1975) showed that barley fed sheep had higher dressing percentages, a thicker subcutaneous fat layer, higher loin-eye area, kidney and pelvic fat percents and better carcass grades and yield grades than fiber fed animals. The fiber fed animals graded low-average and while the controls graded high to good. The high dry matter digestibilities of the rations (Table 11.8) and the resulting high ADGs of the animals (Table 11.7) indicated that the test rations must have contained a large amount of digestible energy. Based on the assumptions discussed in Chapter 8.4 pertaining to digestible energy (DE) intake, the DE values for the individual rations can be derived. I f the DE of the PFW is assumed to be the DE of the ADF component (Table 8.9), then: for the PG PFW, the DE = 3.02 Mcal/kg, and for the K PFW, the DE = 2.46 Mcal/kg. I f the DE of the PFW silage is the sum of the products of DE for each component and i t s proportion in the silage, then using the DE values from the NRC-NAS (1984) for each of the ingredients, the DE for 140 PG PFW barley-whey-urea silage =3.87 Mcal/kg K PFW barley-whey-urea silage =3.31 Mcal/kg Based on these DE values and the DE "book" values for the reitaining feedstuffs in the ration (Table 11.1), the estimated DE values of the individual rations and the total DE intake is shown in Table 11.10. Table 11.10 Estimated digestible energy intakes of the rations fed to beef cattle RATION DE (Mcal/kg)1 INTAKE (kg/D)2 DE INTAKE (Mcal/D) PG22 3.60 10.9 39.2 PG44 3.53 10.4 36.7 K22 3.43 10.3 35.3 K44 3.20 9.8 31.4 1 - digestible energy 2 - taken from Table 11.7 According to the NRC-NAS (1984) to gain 1.36 kg/D, a growing finishing steer must consume 20.06 Mcal/D. The DE intakes of the test rations were estimated to be 31.4-39.2 Mcal/D (Table 11.10). These values would be large enough to support the measured ADG (1.5-1.9 kg/D) (Table 11.7). Since these values are derived partially from DE "book" values, the predicted values are only approximations. As well, the DE of the PFWs may be underestimated since the only ADF is considered to contribute DE. Any associative effects on the DE of the components in the silage and ration during fermentation in the si l o and/or rumen were not considered in this model. In conclusion, based on high digestibility, good intakes, respectable weight gains and feed conversions, ensiled PFW is an excellent energy source for beef cattle. C H A P T E R T W E L V E 141 1 2 . 0 M A C R O A N D T R A C E M I N E R A L C O N T E N T O P K R A F T P U L P M I L L F I B E R W A S T E I N R E L A T I O N T O T H E T O L E R A N C E L E V E L S F O R B E E F C A T T L E 1 2 . 1 I N T R O D U C T I O N In many of the previous studies where PFW was examined, PFW was low in ash but the specific mineral profile was unknown (Dinius and Bond, 1975; Lemieux and Wilson, 1979). However, the amount of ash, i t s composition, and the presence of heavy metals may limit the use of PFW as a feed within rations (Baker, 1973; Mertens and Van Soest, 1971; Dinius et al., 1970; Millett et al., 1973). Mineral levels in PFWs were measured to identify possible mineral toxicities or deficiencies related to the feeding of the PFW to beef cattle. 1 2 . 2 M A T E R I A L S A N D M E T H O D S Samples of K PFW and PG PFW from 1986 (Chapter 8.0) and 1987 (Chapter 10.0) were analyzed by Quanta Trace Laboratories for various macro and trace elements. Subsamples were subjected to a standard nitric perchloric acid and hydrogen chloride digest. These digests were analyzed for heavy metals and trace elements with ICAP AES (Inductively Coupled Argon Plasma Atomic Emission Spectroscopy). Cotton cellulose was the standard reference material. 1 2 . 3 R E S U L T S Table 12.1 shows the mineral profile of PFWs for two years along with the mineral tolerance limits for beef cattle. Alimunum, calcium, iron and 142 possibly cadmium concentrations in the PFW approached tolerance limits for beef cattle (NAS-NRC, 1984). Other heavy metals and other trace element concentrations measured from this period from both PFW sources were below Table 12.1 Mineral profiles of pulp mill fiber waste1 ELEMENT3 Source K PFW of PFW2 PG PFW APR 86 JULY 87 APR 86 JULY 87 ARSENIC (50) 0.4 0.8 0.4 0.4 BORON 3 < 1 < 0.10 < 0.6 BERYLLIUM < 0.09 0.10 < 0.10 < 0.06 BISMUTH < 0.09 < 0.1 < 20 < 0.06 CADMIUM (0.5) < 20 0.3 < 0.5 0.4 COBALT (5) < 0.5 1 < 1.0 < 0.6 CHROMIUM 8.2 5.6 11.0 6.4 COPPER (115) 6 2 9 5 MERCURY (2) < 0.04 0.1 < 0.05 0.03 MOLYBDENUM (6) < 3 < 3 < 3 < 2 NICKEL 3 1.5 4 2 LEAD (30) < 4 < 5 < 5 < 3 ANTIMONY < 0.09 < 0.1 < 0.10 < 0.06 SELENIUM (2) < 0.09 < 0.1 < 0.10 < 0.06 THORIUM < 4 < 5.0 < 5 < 3 URANIUM < 30 < 30 < 30 < 20 VANADIUM 2.5 1.5 3.6 1.5 ZINC (500) 36 18 28 19 ALUMINUM (1000) 953 600 1300 657 BARIUM 96.6 50 17 11 CALCIUM (20000) 20800 10300 2500 3000 IRON (1000) 1310 1320 1460 1140 POTASSIUM (30000) 700 < 500 < 500 < 300 MAGNESIUM (4000) 1700 1200 600 400 MANGANESE (4000) 427 231 55 40 SODIUM (100000) 3400 3000 1200 760 PHOSPHORUS (10000) 300 300 200 < 100 SILICON (2000) 100 90 160 76 STRONTIUM (2000) 55 37 6 7.2 TITANIUM 89 51 74 46 ZIRCONIUM 9 < 10 < 10 < 6 1 - values (ppm) represent the mean of samples analyzed in duplicate and expressed on a dry matter basis 2 - PG PFW = Prince George pulp fiber waste; K PFW = Kamloops pulp fiber waste 3 - figures in brackets represent tolerance levels (ppm) for beef cattle (NAS-NRC, 1984) 143 the tolerance levels for beef cattle (NAS-NRC, 1984). The total percent ash in 1986 and 1987 in the Prince George PFW was 6.26% and 4.34%, and Kamloops PFW was 12.71% and 10.07% respectively. 12.4 DISCUSSION The difference in the total ash content between the K PFW and the PG PFW samples reflected the large amount of wood ash in the Kamloops sample compared to the Prince George sample (J. Zagar, personal cxonmunication). In the K PFW, the high amount of ash may correspond to the larger proportion of calcium (Ca) present. Ca in the form of calcium carbonate was used as a buffer in the Kamloops mill to increase the pH of the waste material (J. Zagar, personal communication). The April 1986 Kamloops sample contained 2.08% Ca. The PG PFW contained respectively 0.25% and 0.30% in 1986 and 1987. Ca was found in approximately the same concentrations as that reported by Croy and Rode (1988) for PFWs from the same locations. Ca within extremes poses no nutritional problem providing a proper calcium:phosphorus ratio is maintained. However, only 300 ppm or less of phosphorus (P) was measured in the PFW. To balance the Ca level, P should be added to the rations containing PFW. Secondary P deficiency is a common result of aluminum (Al) toxicity. In the 1986 samples, both K PFW and PG PFW had Al levels which approached toxicity. Since PFW may contain high levels of Al, adequate P supplementation i s essential. Al contamination may be due to the presence of soil and whitening clays (Croy and Rode, 1988). However, since Al is probably present in an insoluble form, Al toxicity should not pose a serious problem for ruminants (Croy and Rode, 1988). Iron (Fe) was the third element in PFW to have levels which approached the maximum tolerance levels for beef cattle. P deficiency may also be 144 associated with chronic Fe toxicity (Church and Pond, 1982). Fe contamination in the PFW is probably from the s o i l or from the stainless steel equipment and piping used in the pulp process. Inorganic Fe is soluble and i s readily absorbed from the gastrointestinal tract. Iron absorption also can be influenced by the body iron stores (Lloyd et al., 1978). Mertens and Van Soest (1971) shewed ash values varied between 0-20% in 38 different paper samples. Millett et a l . (1973) showed Ca, Al, Fe and sodium (Na) levels in pulp residues were present in levels higher than that found in alfalfa hay. High mineral concentrations could potentially restrict the use of PFW in animal rations. Since PFW on a dry matter basis made up a maximum of 44.4% of the total feed, the mineral concentrations in the diet due to the PFW were diluted. Thus, the mineral concentration for any given element in rations containing PFW would be below tolerance levels. The mineral profile of the PFW from each of the two mills tended to be consistent over the two year period surveyed. However, the mineral content of PFW, as in the case of Ca, may differ between pulp mills. PFW was a suitable animal feed because of the low ash content, the lack of heavy metals and other toxic concentrations of particular elements. However, the mineral content in PFW rations for optimum growth and health of beef animals generally indicated a need for some form of mineral supplementation. C H A P T E R T H I R T E E N 145 1 3 . 0 I D E N T I F I C A T I O N O F C H E M I C A L C O N T A M I N A T I O N A N D T O X I C O L O G I C A L A S S E S S M E N T O F K R A F T P U L P M I L L F I B E R W A S T E A S A F E E D S T U F F F O R B E E F C A T T L E 1 3 . 1 I N T R O D U C T I O N Chemical analyses of pulp and paper effluents have identified numerous compounds with toxicological potential (McKean, 1980; Kringstad and Lirristrom, 1984). Certain fractions of pulp effluents showed mutagenic activity in vitro in both bacterial (McKague et al., 1981; Nestmann et al., 1979) and yeast (Nestmann and Lee, 1983) assays. The presence of resin acids, chlorinated resin acids, chlorinated phenols and guaiacols derived from the kraft process and sequential bleaching stages have contributed to the effluents' toxicity and mutagenicity (Walden and Howard, 1981; Kubic and Jackson, 1981; McKague, 1981b). In addition, various dioxin and furan isomers have been identified in wood products (Van Strum and Merrell, 1987). Biologically active chemical toxins such as these may also be present in PFW. The possible presence of these chemical contaminants poses a problem if PFW i s fed to meat or milk producing animals. No previous studies have characterized the chemical composition of PFW in terms of its toxic potential. The objective of this study was to assess the toxicological potential of two different PFWs in a short-term mutagenicity test and a long-term animal feeding t r i a l . 1 3 . 2 M A T E R I A L S A N D M E T H O D S 13.2.1 IDENTIFYING AND QUANTIFYING COMPOUNDS In June 1987, PG PFW and K PFW were obtained. These were the same PFWs 146 used in the feeding t r i a l described in Chapter 11.0. Samples were measured for total resin acids, chlorinated phenols, dioxins and furans. BC Research (Vancouver, B.C., Canada) analyzed the wet PFW samples and beef liver for total resin acids and chlorinated phenols. Subsamples were adjusted to pH 8.0 (neutral fraction) and extracted twice with diethyl ether:methanol (8:1). The remainirig pulp fiber was acidified with sulfuric acid to pH 1.0 (acidic fraction). Both the neutral and acidic fractions were extracted into dichloromethane which was subsequently replaced with isc—cctane by rotary evaporation. The iso-octane extracts were methylated, adsorbed onto a F l o r i s i l column and eluted with petroleum ether (fraction 1) and petroleum ether:ethyl acetate (98:2) (fraction 2). Both fractions were injected into a gas liquid chromatograph (GLC) (HP 5880A) equipped with a capillary column (DB1) and flame ionization detector. Resin acids were detectable above 200 ppb. Both fractions were chromatographed on a second capillary column gas liquid c±iramatograph (HP 5710A) equipped with an electron capture detector. Chlorinated guaiacols were detectable above 10 ppb. A PFW sample spiked with a mixture of resin acids, chlorinated guaiacols and terpene/phenols assured quality control. A reagent blank indicated any interferences. Mann Testing Laboratories (Mississauga, Ontario, Canada) analyzed the PFW and biopsied beef liver tissues for dioxins and furans. Homogenized samples were digested in concentrated hydrochloric acid and extracted with 1% (iLchloromethane in hexane. A l l samples were subjected to a multi-adsorbent column cleanup (Parski and Nestrick, 1980) to reduce sample background. The samples were analyzed by GLC under electron impact conditions at a 300-500 molecular equivalent range. Gompounds were identified on the basis of their specific retention times, f u l l scan analysis and parent ion cluster ratios of the sample and standard solutions. 147 Quality control was assured by spiking samples with carbon-13 labelled tetrachlorcdibenzcdioxin (C13-TCDD) and cctacMorodibenzodioxin (C13-OCDD). 13.2.2 SATMTWFTIA/MAMMATX AN-MTfT?OSnMR TEST The Ames test, a mutagenicity assay, was performed on the water soluble and organic soluble fractions of the PFWs. Water soluble fractions (10 g in 200 ml deionized water) and organic fractions (10 g in 200 ml chloroform:methanol (4:1)) were obtained by mixing the slurry solutions in a shaker-incubator for 24 hr at 25°C. Slurries were gravity filtered. Water soluble fractions were freeze-dried and organic fractions were concentrated in dimethylsulfoxide (DMSO) by rotary evaporation. Aqueous samples were sterilized by passing the solution through a membrane f i l t e r (0.2 nm, Nalgene) prior to assay. The Ames test was performed, without metabolic activation, with histidine-dependent mutant strains (TA 98, TA 100 and TA 1537) of Salmonella typhimurium obtained from BC Research and handled according to Nestmann et al., 1980. A l l colonies were counted manually or when appropriate by a colony counter. Controls included the number of spontaneous revertants in sterile water, DMSO, sodium azide, 9-aminocridine and 2-nitrofluorene. Samples are considered mutagenic i f there is a 2-3 fold increase in revertant colonies over that in the negative controls. 13.2.3 ANIMAL STUDY PFW was ensiled and formulated in rations as outlined in Chapter 11.0. Following the 63 day feeding t r i a l , a veterinarian examined Hereford-cross long yearling steers. Liver biopsy samples were performed according to the procedure of Chapman et al. (1963). Samples (0.5 g) were taken from three animals from each of the control, 44% ensiled PFW Kamloops (K44) and Prince George (PG44) fed groups. The liver samples from similar treatments were 148 composited and analyzed f o r d i o x i n s , f u r a n s , r e s i n a c i d s and c h l o r i n a t e d phenols as o u t l i n e d above. 13.3 RESULTS R e l a t i v e m o i s t u r e content, t o t a l r e s i n a c i d s and c h l o r i n a t e d g u a i a c o l composition f o r t h e PFW samples a r e r e p o r t e d i n Table 13.1. To some e x t e n t t h e lower m o i s t u r e content o f t h e K PFW sample c o n t r i b u t e d t o h i g h e r c o n c e n t r a t i o n s o f t h e r e s i n a c i d s as sampled on a wet b a s i s compared t o t h e PG PFW samples. However, i n p a r t i c u l a r , l e v o p i m a r i c , a b i e t i c and n e o a b i e t i c a c i d c o n c e n t r a t i o n s (246.35, 81.11, 13.65 ppm r e s p e c t i v e l y ) were e l e v a t e d i n t h e K PFW compared t o t h e PG PFW on a d r y matter b a s i s . T a ble 13.1 C o n c e n t r a t i o n o f r e s i n a c i d s and c h l o r i n a t e d compounds i n t h e P r i n c e George and Kamloops p u l p f i b e r wastes PRINCE GEORGE KAMLOOPS Compound PFW PFW RESIN ACIDS 2 PIMARIC 40. 9 2 1 75. 16 SANDARACOPIMARIC 6. 68 13. 00 ISOPIMARIC 62. 10 97. 30 LEVOPIMARIC 17. 02 81. 11 DEHYDR0ABJLET1C 46. 95 68. 50 ABIETIC 50. 62 246. 35 NEOABIETIC 2. 84 13. 65 CHLORINATED GUAIACOLS 3 TRI-C1 GUAIACOL 0. 025 0. 023 TETRA-C1 GUAIACOL 0. 096 0. 311 % MOISTURE 76. 67 62. 84 pH 8. 0 9. 0 1 2 3 - v a l u e s (ppm), on a wet weight b a s i s , r e p r e s e n t s i n g l e samples - d e t e c t i o n l i m i t f o r r e s i n a c i d s i n PFW i s 0.200 ppm - d e t e c t i o n l i m i t f o r c h l o r i n a t e d g u a i a c o l s i n PFW i s 0.010 ppm 149 Table 13.2 Dioxin and furan detection levels and concentrations in the pulp mill fiber wastes (PFW) OCMPOUND1 KAMLOOPS PFW PRINCE GEORGE PFW (Cumulative isomer) DR MDL DR MDL TETRA-CDD (0.1)2 5.0 - 0.2 PENTA-CDD (0.1) 1.8 - 0.2 HEXA-CDD (0.1) 1.7 - 0.3 HEPTA-CDD (0.3) 1.0 - 0.5 OCTA-CDD (0.3) 1.0 — 0.5 TETRA-CDF (0.1) 9.3 1.2 — 0.2 PENTA-CDF (0.1) 1.8 - 0.2 HEXA-CDF (0.1) 1.7 - 0.3 HEPTA-CDF (0.3) 1.0 - 0.5 OCTA-CDF (0.3) 1.0 0.5 1 - values, on a wet weight basis, represent a single measurement DR = detectable residue (ppb); MDL = method detection limit (ppb) ; - = none detected; CDD = chlorodibenzodioxin; CDF = chlorodibenzofuran. 2 - values in brackets indicate background detection limit for an external blank where recovery was 78% for C13-TCDD and 96% for C13-0CDD. Sample matrix recoveries were 61% and 47% for C13-TCDD and C13-OCDD in K PFW; sample matrix recoveries were 95% and 85% for C13-TCDD and C13-OCDD in the PG PFW In addition to the resin acids detected in the PFW, Table 13.1 also shows K PFW contained tetrachloroguaiacol in substantially greater amounts than the PG PFW (respectively 0.311 ppm and 0.096 ppm). Total tetrachlorodibenzofurans (TCDF) were found in the K PFW sample at 9300 ppt (Table 13.2). This concentration refers to the cumulative total of a number of different tetra-chlorinated furan isomers. Yet, no dioxins or furans in the PG PFW sample were identified with a detection limit of 200-500 ppt. Table 13.3 shows the results of the Ames test when the aqueous and organic PFW fractions were tested. Fractions were tested without metabolic activation, since metabolic activation had not enhanced mutagenicity in pulp mill effluents in previous studies (McKague et al., 1981b). No mutagenicity 150 Table 13.3 Number of revertant colonies 1 of Salmonella typhimurium induced by pulp fiber waste extracts BACTERIAL STRAIN SAMPLE TA 98 TA 100 TA 1537 CONTROLS: DMSO (100 iii) (500 s l ) WATER (100 al) (200 ill) (500 s l ) (700 al) (1000 a l ) (2000 al) 2-NITR0FLU0RENE (50 aq) SODIUM AZIDE (10 ag) 9-ANIN0ACRIDE (100 sq) 45' 139 10 32 49 6 - 172 6 35 235 -- 171 9 41 196 -1363 - -- 2205 -- - 1420 KAMLOOPS EXTRACTS! WATER SOLUBLE BACTERIAL STRAINS c o n c e n t r a t i o n TA 98 TA 100 TA 1537 (aq/plate) ORGANIC SOLUBLE BACTERIAL STRAINS c o n c e n t r a t i o n TA 98 TA 100 TA 1537 (aq/plate) 0.53 - 236 20 0.27 34 216 11 1.50 43 272 0.58 40 187 13 2.47 41 253 - 1.74 36 118 7 5.04 41 268 2.90 40 24 6 7.50 - 228 PRINCE GEORGE EXTRACTS: HATER SOLUBLE BACTERIAL STRAINS ORGANIC SOLUBLE BACTERIAL STRAINS c o n c e n t r a t i o n TA 98 TA 100 TA 1537 c o n c e n t r a t i o n TA 98 TA 100 TA 1537 (aq/plate) (aq/plate) 0.52 19 196 9 0.33 24 234 22 1.35 33 204 10 0.69 37 214 16 2.70 - 241 - 1.98 47 - 15 4.90 35 194 - 3.30 38 76 6 1 - values represent mean of dupl icated plates in the Salmonella typhimurium strains was observed in either the aqueous or organic fractions of either PFW. The average feed intake, average daily gain and feed conversions of the 151 beef steers fed PFW during a 63 day t r i a l are shown in Table 11.7. The weight gains are described in Tables 11.8 and 11.9, and Figure 11.2. Although ADG was significantly higher in the control animals compared with Table 13.4 Method detection levels of analyses of dioxins and furans in beef livers COMPOUND RATION FED: CUMULATIVE BLANK CONTROL4 K444 PG444 ISOMERS CONC1 MDL1 CONC MDL CONC MDL CONC MDL TETRA-CDD1 _2 0.03 _3 0.2 - 0.5 0.2 PENTA-CDD - 0.03 - 0.2 - 0.5 0.2 HEXA-CDD - 0.05 - 0.3 - 0.9 0.5 HEP1A-CDD - 0.2 - 1.7 - 3.5 2.4 OCTA-CDD — 0.2 — 2.5 — 5.3 3.6 TETRA-CDF1 — 0.03 _ 0.2 _ 0.5 0.2 PENTA-CDF - 0.03 - 0.2 - 0.5 0.2 HEXA-CDF - 0.05 - 0.3 - 0.9 0.5 OCTA-CDF — 0.2 — 2.5 — 5.3 3.6 RECOVERIES (%): C13-TCDD 74 95 80 108 C13-0CDD 108 103 108 100 1 - CONC = concentration present in sample (ppb) ; MDL = method detection levels (ppb) ; CDD = chlorinated dibenzodioxin; CDF chlorinated dibenzofuran 2 - not detected 3 - single composited sample from 3 animals 4 - CONTROL = barley/hay fed animals; K44 = animals fed 44% Kamloops pulp mill fiber waste; PG44 = animals fed 44% Prince George pulp mill fiber waste the animals fed 44% ensiled PFW, a l l groups showed respectable weight gains. No significant difference (P < 0.05) in FI or F/G between groups was measured. No resin acids, chlorinated guaiacols of dioxins were detected in the liver samples of the beef cattle in this study. The detection levels for the resin acid and chlorinated guaiacols were 400 ppb and 10 ppb respectively. The method detection levels of dioxins in the liver tissue range from 0.2-0.5 ppb (Table 13.4). 152 13.4 DISCUSSION Abietic, levopimaric and neobetic acids were found in higher concentrations in the K PFW compared to that of the PG PFW. However, relatively high concentrations of pimaric and isopimaric acids were also identified in the PFWs (Table 13.1). These resin acids identified in the PFW samples corresponded to those found in pulp and paper effluents (Oikai and Holmbom, 1986). These compounds were present in concentrations above levels known to be hazardous to fish and other aquatic organisms (Hemingway and Greaves, 1973). According to McKean (1980), the 96 hr LC50 values of echo salmon (a standard toxicity bioassay where 50% of the test population survives after a 96 hour exposure to a known concentration of a certain substance) indicated approximately 80% of the toxicity associated with the total mill effluent was attributed to the resin acid content. Of the resin acids present, pimaric acids are generally more toxic than abietic acids (Leach and Thakore, 1974b). Tetrachloroguaiacol and tricMoroguaiacol, derived from the chlorination of lignin, were also identified in the PFWs. Both compounds are toxic to fish (McKean, 1980). Unlike resin acids, chlorinated guaiacols persist in the environment and may eventually lead to bioaccumulation in the ecosystem. TetracMorodilDenzofurans were also identified in the K PFW. Since each isomer varied in i t s relative toxicity (McConnell and Moore, 1979), assessing the overall toxicity due to the TCDF isomers in the K PFW was difficult. The PG PFW showed no dioxins or furans. However, the relatively high detection limits for tetracMorodibenzodioxins (2,3,7,8-TCDD) (K PFW = 5.0 ppb and PG PFW =0.2 ppb) in this study precluded any estimation of their presence at lew levels in either PFW sample. Although the World Health Organization has suggested that man is less sensitive to polychlorinated dibenzo-dioxins and polychlorinated dibenzo-furans than 153 other mammalian species (Nygren et al. , 1986), both American and Canadian agencies have classified TCDD as a possible carcinogen. No mutagenic activity was observed with the PFW samples (Table 13.4). Pulp mill effluents have shown mutagenic activity with the Salmonella-microsome assay (McKague et al. , 1981b; Nestmann et al. 1979; 1980). The lack of mutagenicity in our study may be partially explained by relatively low substances present in the PFW. While pure standards of resin acids levels of mutagenic compounds compared to other toxic, nonmutagenic including abietic, levopimaric and pimaric acids showed no mutagenic activity with the Ames test, neoabietic acid has shown a dose-related mutagenic response (Nestmann et al., 1979). In this study K PFW showed no mutagenicity even though neoabietic acid was detectable. Halogenated carcinogens such as TCDD failed to induce mutagenicity in short-term mutagenicity assays (Ames and McCann, 1981). During the feeding t r i a l , the beef steers showed no visual signs of toxicity. A l l animals had respectable weight gains (Table 11.7). Weight gain was linear (Figure 11.2) and constant throughout the measured period (Table 11.9). Other studies also reported no change in weight gain, feed consumption and milk production following the feeding of a r t i f i c i a l l y high levels of TCDD in the form of 2,4,5-trichlorophenoxyacetic acid to beef cattle and Holstein dairy cows (Jensen et al. , 1981; Jensen and Hummel, 1982). Although known toxic campounds were identified in the PFW samples in this study, no resin acids, chlorinated guaiacols or TCDFs were detected in the liver samples of the beef cattle fed contaminated PFW. Microbial degradation of resin acids in pulp mill effluents is known to occur (Nestmann et al. , 1979). Possibly bioaccumulation of resin acids did not occur i f the rundnal microflora rumen degraded any resin acids in the feed. 154 However, the absence of dioxins in the liver samples was contrary to former studies (Jensen et al., 1981). Traces of dioxins in liver tissue (7-10 ppt) were reported in four cattle who consumed an average total of 3.9 ng TCDD in 28 days with feed which contained 0.024 ppb 2,3,7,8-TCDD (Jensen et al., 1981). In this study beef cattle consumed an average total 15.45 mg TCDF in 63 days with feed which contained 25 ppb TCDF. The differences between the studies may be attributed to the lower dioxin detection limits in Jensen's two study. Also, the liver biopsy technique used in both studies may not have permitted adequate sampling compared to a slaughter technique. Possibly the variation in the response of the animals, and the experimental error due to the analyses of minute quantities of the specific measured compounds in small sample sizes may partially account for some of the variation between the studies. The levels of TCDD found in liver, kidney and muscle of beef cattle fed TCDD were considerably lower than the TCDD level in the diet as reported by Jensen et a l . (1981). However, the beef fat was found to accumulate approximately four times that found in the diet. Jensen et al. (1981) suggested beef fat was the most sensitive beef tissue to monitor TCDD exposure. However, the variability was high when analyzing less than 100 ppt of TCDD in unrendered beef fat samples (Jensen et al. , 1981). Although back fat samples were taken from the beef cattle used in this study, due to poor recoveries of TCDD standards in control samples, the results could not be reported by EPA standards. In summary, the results of this study show that potentially toxic chemical compounds were present in PFW and that the concentrations of these compounds may differ between pulp mills. The differences in PFW composition from the two kraft mills reflected varying wood species, pulp washing practices and bleaching operations. Chemical characterization of PFWs from 155 each mill is essential to determine the suitability of PFW as a ruminant feed. Toxicological assessments of the chemical constituents in PFW including their bioactive properties are also recommended. Despite the identification of potentially toxic (Compounds in the PFW, no chlorinated phenols could be detected in the livers of beef animals exposed to this contaminated feed. These results raise questions corK^erning the biological significance of trace levels of contaminants in PFW and the safety of feeding this material to meat or dairy producing animals. Before reaching any conclusions concerning the safety of PFW as a feed, further studies on the bioavailability and tissue accumulation of chlorinated organics in the runuxiant are required. C H A P T E R F O U R T E E N 156 1 4 . 0 G E N E R A L D I S C U S S I O N 1 4 . 1 E C O N O M I C E V A L U A T I O N O F F E E D I N G P U L P M I L L W A S T E S I L A G E To a certain degree the economics of a feedstuff dictate i t s use and feasibility when formulating animal rations. A feedstuff aside from having some nutritive quality, must be available, and must be economically competitive with other feeds. PFW i s generally regarded as an economic l i a b i l i t y . However, as a feed for the beef cattle, PFW may be a profitable, useful commodity. In the central interior of British Columbia grain prices often are relatively high, and hay making weather is unpredictable. Of the 27 pulp mills in British Columbia, 18 utilize the kraft process (Williamson, 1987). PFW is abundant, and i f available in proximity to feedlots, is a cost effective feedstuff. PFW is very expensive to transport because of the bulk of the material and weight due to the water content. The main market for PFW must then be relatively close to i t s source. Figure 14.1 shows the distribution of pulp mills in British Columbia relative to the cattle grazing areas. As an inexpensive commodity, PFW in British Columbia would only be practical in the central interior (ie. Prince George, Quesnel, Kamloops), in the Kootneys (Cranbrook and Castlegar), and possibly in some areas in the lower Fraser Valley). Calculated costs for PFW silage and rations are shown in Tables 14.2-14.7. Costs are based on 1987 prices, and the assumptions outlined in Table 14.2. PFW barley-whey-urea silage would cost $1302.87 i f 49.75 tonnes of silage (theoretical DM = 31.37%) were made. Table 14.4 shows the total cost of PFW silage including the cost of ingredients (Table 14.2), and the additional cost of ensiling (Table 14.3). 157 Figure 14.1 Distribution of kraft pulp mills in relation to cattle grazing areas in British Columbia. 158 The costs of the PFW silage losing the Ag Bag and bunker silo for ensiling were respectively $88.6 and $42.3 per metric ton on an as fed basis. There was a relatively large cost difference between the use of Ag Bags (Chapter 11.2) and bunker silos. The cost of the silages were $282.3 and $134.8 per metric ton on a dry matter basis. The feeding costs of 22% PFW, 44% PFW and grain-hay based rations fed to a herd of 50 beef steers for 75 days are shown in Tables 14.5, 14.6, and 14.7. Table 14.1 Assumptions pertaining to the cost of PFW and whey TRANSPORTATION COST OF PFW: 1) Pulp mill is within a 80.5 km radius from the feedlot 2) Cost included 8 loads (2.74 tonnes/load) for a total of 21.84 tonnes wet PFW 3) Based on 1) and 2), cost for PFW transport is $0.30/km, or $48.39/161 km/2.73 tonnes, or $17.73/tonne TRANSPORTATION AND CONDENSING COSTS OF WHEY: 1) Dairy i s within a 24 km radius from the feedlot 2) Transport costs assume carrying capacity of a f u l l load (25,000 1) raw liquid whey = $0.80/100 1 condensed whey (assuming 28% solids) = $0.20/100 1 = $0.19/100 kg 3) Cost of condensing whey (via ultrafiltration) = $0.26/100 1 = $0.25/100 kg 4) Considering 1), 2), and 3) cost of condensed whey including transport = $44.00/tonne Table 14.2 Cost of ingredients and total ingredient cost of pulp mill fiber waste (PFW) barley-whey-urea silage INGRED. %DM %DM IN TOTAL AMT2 UNIT TOTAL DIET1 DM (MT) PRICE PRICE ($) PFW 25 74 296 43.68 17.73/MT3 774.45 BARLEY 90 20 22.2 3.28 100.00/MT 327.60 WHEY 28 5 17.9 2.64 44.00/MT4 116.16 UREA 100 1 1.0 0.15 572.00/MT 84.66 TOTAL 100 337.1 49.75 1302.87 1 - percentage of feedstuff in silage on a DM basis 2 - amount utilized incorporated in silage (air dry basis) 3 - based on transport costs alone; assumed a zero cost at the mill 4 - based on transport and condensing costs 159 Table 14.3 Costs of ensiling pulp mill fiber waste, other than ingredient costs Rental of Ag Bagger and Ag Bags Rental of harvester ($100/D) for grinding Extra machinery: Cost ($) 2303 400 mixing wagon 400 2 tractors Total 31031 1 - note labour costs are not included Rations containing 22% PFW, 44% PFW and grain-hay would cost $0.99, $1.14 and $1.17 per kg gain (Table 14.8). The relatively higher cost of the 44% PFW ration compared to the 22% PFW ration was attributed to the high relative cost of the protein in the remainder of the ration. Using a bunk silo, PFW rations would be cheaper than a grain-hay ration based on cost per gain. However, since the ADG of the 44% PFW ration was significantly lower (P < 0.05) than the grain-hay ration (Chapter 11.0), the number of days to market would be higher. This price differential would not warrant the use of PFW. But with a 22% PFW ration, the use of PFW may be cost effective compared to traditional grain-hay rations. Since the ADG between these two groups is similar, and i f the number of days to market is assumed to be the same, there may be a considerable savings in terms of profit for the producer using PFW in his ration. In addition, this cost differential may be increased by eliminating whey from the ration depending upon its effect on weight gain and number of days to market. Table 14.4 Total cost of pulp mill fiber silage ENSILING METHOD AG BAGS BUNKER SILO INGREDIENT COSTS 1302.9 1302.9 OTHER 3103.0 800.0 TOTAL (S/49.7 MT) 4405.9 2102.9 COST ($/MT) 88.6 42.3 COST ($/MT DM) 282.3 134.8 160 Table 14.5 Cost of a pulp mill fiber (PFW) ration containing 22% PFW, an equivalent of 30% PFW silage for a herd of 50 beef steers for 75 days. INGREDIENT %DM IN INTAKE2 %EM3 INTAKE2 INTAKE4 PRICE COST5 DIET1 (DM) (AIR DRY) (MT) ($/MT) ($) SILAGE 0.3 3.27 0.26 12.6 47.163 88.56 4176.76 HAY 0.1 1.09 0.94 1.2 4.348 301.70 1311.91 CANOLA 0.47 5.07 0.87 5.8 21.858 100.00 2185.83 BARLEY 0.13 1.47 0.93 1.6 5.923 126.51 749.31 PREMIX 75 G/HD 0.08 1.00 0.1 0.281 1050.00 295.31 T . T M R 0.02 0.23 1.00 0.2 0.869 85.00 73.87 SALT ad l i b . 4 .75/block 95.00 TOTAL ($ /50 head/ 75 days) 8887.99 1 - percentage on a DM basis of feedstuff in complete ration 2 - intake (kg) per animal per day; total daily DM intake per animal is 10.9 kg when silage is fed at 30% of ration (Table 11.7) 3 - percentage DM of the particular feedstuff 4 - intake (MT) per herd of 50 steers for 75 days 5 - cost assumes 49.7 MT of silage are made (Table 14.3) Table 14.6 Cost of a pulp mill fiber (PFW) ration containing 44% PFW, an equivalent of 60% PFW silage for a herd of 50 beef steers for 75 days. INGREDIENT %DM IN INTAKE2 %DM3 INTAKE2 INTAKE4 PRICE COST5 DIET1 (DM) (AIR DRY) (MT) ($/MT) ($) SILAGE 0.60 6.24 0.26 24.0 90.000 88.56 7970.40 HAY 0.10 1.04 0.94 1.1 4.149 301.70 1251.73 CANOLA 0.26 2.71 0.87 3.1 11.689 100.00 1168.92 BARLEY 0.04 0.41 0.93 0.4 1.646 126.51 208.18 PREMIX 75 G/HD 0.80 0.08 1.0 0.281 1050.00 295.31 T . T M R 0.02 0.18 1.00 0.2 0.668 85.00 56.78 SALT ad l i b . 4 •75/block 95.00 TOTAL ($ /50 head/ 75 days) 10913.13 1 - percentage on a EM basis of feedstuff in complete ration 2 - intake (kg) per animal per day; total daily DM intake per animal is 10.4 kg when silage is fed at 60% of ration (Table 11.7) 3 - percentage EM of the particular feedstuff 4 - intake (MT) per herd of 50 steers for 75 days 5 - cost assumes 49.7 MT of silage are made (Table 14.3) 161 Table 14.7 Cost of a barley-alfalfa hay ration for a herd of 50 beef steers for 75 days INGREDIENT %DM IN INTAKE2 %DM3 INTAKE2 INTAKE4 PRICE COST DIET1 (DM) (AIR DRY) (MT) ($/MT) ($) HAY 0.20 2.22 0.94 2.4 8.856 301.70 2671.97 BARLEY 0.80 8.88 0.93 9.5 35.806 126.51 4529.87 SUPPLEME 75 G/HD 0.08 1.00 0.1 0.281 1050.00 295.31 LIME 0.21 2.29 1.00 2.3 8.587 85.00 729.92 SALT ad l i b . 4.75/block 95.00 TOTAL ($ /50 head/ 75 days) 8322.07 1 - percentage on a DM basis of feedstuff in complete ration 2 - intake (kg) per animal per day; total daily DM intake per animal is 11.11 kg (Table 11.7) 3 - percentage DM of the particular feedstuff 4 - intake (MT) per herd of 50 steers for 75 days Table 14.8 Summary of total cost of feed for a herd of 50 beef steers for 75 days using Ag Bags or bunker silos for ensiling AG BAG SILO BUNKER SILO RATION ADG1 TOTAL2 COST3 COST4 TOTAL2 COST3 COST4 ($) ($/DAY) ($/GAIN) ($) ($/DAY) ($/GAIN) PFW22% 1.8 8887.99 2.37 1.32 6704.81 1.79 0.99 PFW44% 1.6 11046.36 2.94 1.83 6880.22 1.83 1.14 GRAIN-HAY 1.9 8322.07 2.22 1.17 8322.07 2.22 1.17 1 - average daily gain (Table 11.7) 2 - total feed costs for a herd of 50 beef steers (Tables 14.5, 14.6, 14.7) 3 - feed costs per animal per day 4 - feed cost per kg live weight gain 14.2 FEASIBILITY OF PULP MILL FIBER WASTES AS RUMINANT FEEDSTUFFS Environmental and economic concerns center around better and more efficient utilization of existing raw materials and "in process" raw materials. Rumen microflora are able to convert cellulosic wastes into metabolizable energy. This energy in turn is used for the production of milk and meat. Pulp fiber waste is a suitable ruminant feedstuff since PFW is available in bulk, not seasonally dependent, and cheap when utilized near the mill, providing no additional processing is required. 162 The viability of feeding PFW under feedlot conditions include the mechanization of ensiling and feeding processes. PFW silage is a heavy bulk material, so a high investment in machinery is required for i t s efficient handling. Chopping, mixing and ensiling PFW is labor intensive. The presence of rocks and stones in the PFW is a problem with machinery. Since the moisture contents of PFW and corn silage are similar, similar machinery and methods of ensiling could probably be used. The PFW is available year round. However, the production of silage is not recommended in the colder months. In the winter raw PFW freezes, making i t very dif f i c u l t to handle. When PFW i s ensiled, bunker silos may be preferred to tower silos or to Ag Bags. Bunker silos were not used any any of any experiments conducted in this study but the loss in nutritive quality was assumed to be not excessive. Damage caused by acids and excessive runoff are problems with forages containing more than 75% moisture ensiled in tower silos (Fisher et al., 1985). If the water is not bound up in the mixture, water may accumulate at the bottom of the silo. This high moisture silage at the bottom is prone to C l o s t r i d i a development which may affect fermentation and silage quality. Ag Bags provided a good fermentation and anaerobic conditions for the ensiling of PFW. However, problems with aerobic deterioration were experienced once holes or rips occurred in the plastic. In addition the costs of packing, labor, machinery and the plastic bags were relatively high, and increased the unit price of the silage dramatically despite the low price of the PFW (Tables 14.4 and 14.8). The K PFW may be preferable to the PG PFW since he drier material is more easily handled and shipping expenses are lower per tonne dry matter. Primary sludge, which becomes the PFW, is collected from a water slurry at the mill. Some of the water in the primary sludge is eliminated by presses at the pulp mill. The type of press at the mill determines the moisture 163 content of the PFW. The moisture content of the PG PFW used in this study was approximately 75%, but the moisture content of other PFWs may be higher (Croy and Rode, 1988). Due to the consistency of the material itself, mechanical removal of the majority of the water i s very di f f i c u l t (NRC, 1983). To dry the PFW on large scale would be expensive. According to Gilles (1978), once conventional pulp i s dried, upon rehydration the feeding value was poorer than the original product. If PFW was introduced as a feedstuff to implement PFW as a manageable commodity, close cooperation between the feed industry and pulp industry would be necessary, as would cooperation between pulp mill personnel and regional agrologists. The advantages of using PFW as a feedstuff are : 1) uniformity in chemical and physical characteristics, 2) ability to be blended in complete rations, 3) maintenance of normal rumen function, 4) energy value, 5) competitive cost, 6) availability. 14.3 ENVIRONMENTAL CONSIDERATIONS The hazard or danger from a specific cause or source is interpreted as "risk". The risk factor for a specific source to a particular individual can be defined as the product of the exposure to the source, susceptibility of the individual and the associated consequences of the exposure. The risk assessment is complicated for a particular substance which contains a mixture of potentially hazardous chemicals. To assess the risk of using PFW as a feed, the following must be considered: 1.) the proportion of PFW in the cattle ration, 2.) the concentration of contaminants in the PFW, and 3.) the true absorption and retention of chemicals in the PFW. In vitro identification of toxic chemicals is an indicator only and cannot substitute for whole animal testing when assessing the overall toxicity. 164 The mere presence of a compound does not necessarily imply any biological significance. Using current technology, parts per t r i l l i o n and parts per quadrillion of compounds can be detected in air, soil, water, food, and tissues. The long-term affects of such minute quantities of potentially toxic chemicals, in many cases, are unknown. However, the presence of some compounds, such as dioxins, even in minute quantities may produce, serious consequences (Nygren et al. , 1986). The risk assessment of a material such as PFW is, then, very difficult, the fear being that once toxic and stable substances are incorporated into the ecosystem, they persist, are virtually impossible to remove, and may have irreversible consequences (Westing, 1978). Extractives, chlorinated phenols and a wide range of substances contribute variable amounts of toxicity to pulp mill effluent. The acute toxicity of bleach kraft mill effluents varies widely between mills and between effluents from the same mill discharged at different times (Walden and Howard, 1981; Mueller and Walden, 1976; Leach et al. , 1978a). PFW has been shown to contain some of the same chemical contaminants as those identified in pulp mill effluent. It is possible, though unlikely, that the compounds quantified in the PFW reflected the variation shown in effluent fractions. To what extent the PFW was contaminated is unknown. The investigations described in this thesis relate to the feeding of PFW to ruminants. However, the discovery of chemical contaminants in the PFW negates the usefulness of PFW as a feed, and at the same time raises the issue of the disposal of the chemically contaminated discharge, and problem of accumulation of such chemicals in the environment. The incineration of PFW and compounds, such as dioxins and related compounds present in PFW, in hog fuel burners may not be complete. Dioxins are only destroyed at temperatures above 800°C (Liberti and Brocco, 1982; 165 Cattabeni, 1978). Stable chemical contaminants may be passed on in the form of ash or bound to particulate matter and released into the atmosphere. The fate of dioxin-related compounds once in the atmosphere is unknown. Thus, proper disposal techniques should be considered. Possibly secondary chambers to capture the emissions, and burners at high enough temperatures to destroy the dioxins are necessary. In a landfill situation, the chemical contaminants in PFW are spectulated not to spread throughout the soil but rather remain relatively stable except near the surface where evaporation may occur. However, dioxin related compounds have half-lives which may be weeks or years depending on the conditions (Freeman and Schroy, 1978). The presence of contaminants in PFW has potentially serious environmental repercussions and should not be ignored. The value of PFW as a feed, coupled with the risk associated with the chemical contamination in PFW justifies further work in this area. 14.4 RECOMMENDATIONS An attempt was made in this study to evaluate PFW as a cattle feed. Much more work on its handling properties and the biochemical reactions which occur in the animal ingesting PFW could be done. Further investigation in these areas should be, however, secondary to the elimination of the contaminants. 1.) There is a large variation in chemical composition between PFWs from mills which use the same process (Mertens and Van Soest, 1971; Millett et al., 1973; Croy and Rode, 1988). A l l recommendations pertaining to PFW as animal feeds should be on a site-specific basis. Several factors influence the value of PFW as a feed including degree of delignification, the washing 166 of the unbleached pulp, and the bleaching conditions in the pulp mills. Specific recommendations concerning the suitability of PFW as a feed should be based on the chemical composition of the PFW, and the presence of potentially toxic contaminants. 2. ) Since some of the chemicals present in PFW are suspected carcinogens and teratogens, reproductive studies would indicate long term affects of feeding PFW. Direct animal toxicity and animal carcinogen studies, though expensive, could better define the toxicological implications of feeding PFW. 3. ) The Ames test is not recommended for the direct testing of mutagenicity in PFW due to the mixture of compounds present in PFW. A wide variety of metabolites of drugs and other ingested compounds appear in the urine. Urine tests detect carcinogens requiring metabolic activation for mutagenic activity where the standard in vitro liver microsomal method fa i l s (Ames et al., 1975). Testing urine of experimental animals using the Salmonella test system could be an option for mutagenesis screening (Ames et al., 1975). 4. ) Lipophilic chlorinated hydrocarbons accumulate in milk (Jensen, 1987; Jensen and Hummel, 1982; Fanelli et al., Nau et al., 1986). Monitoring the retention and metabolism of such compounds by lactating animals also could be useful in determining the metabolism of such compounds in PFW. 5. ) Discharges and raw products from pulp and paper mills should be assessed for contamination. However, analysis is often limited by the high cost and suitable laboratory facilities. A greater urderstanding of the environmental impact and low level, long-term effects from chemical 167 pollutants identified in this thesis, should be explored. To assure minimal irreparable damage, exposure to hazardous chemicals must be reduced to minimal levels. 6. ) Adhering to environmental guidelines which consider no-effect levels (NEL) rather than acute toxicity would decrease the stress on the environment. In Canada a regulatory grey zone has existed with regard to pulp and paper discharges. In the past the pulp and paper industry has tried to identify and to minimize environmental impact. Yet with the recent concern of possible toxicants, a review of process operations and i t s consequences is necessary. Government and industry together must work to set regulations and codes of conduct to avoid environmental contamination by hazardous wastes. In some places in Europe heavy taxes on excess discharges enforce laws on toxic emissions by pulp mills (Van Strum and Merrell, 1987). Lastly consumer education to accept less bleached materials as an option would ease the burden of producing highly bleached paper goods. 7. ) Banning chemical production, incineration and other sources which emit hazardous compounds are not always feasible without providing alternatives. Oxygen treatment of kraft pulp before bleaching, combined with partial replacement of chlorine with chlorine dioxide (Smith, 1981) reduces toxicity, mutagenicity, color and organic load of bleach plant effluents (Kringstad and LirKistrom, 1984). This alternative to chlorine bleaching is used in Sweden, West Germany and Japan. 168 CHAPTER FIFTEEN 15.0 CONCLUSIONS 1. ) Ensiling PFW was shown to be an effective preservative and storage technique. Probably bunker silos would be more cost efficient than Ag Bags although Ag Bags did provide suitable and effective anaerobic conditions for ensiling. 2. ) Ensiled PFW was more palatable and more digestible than non-ensiled PFW. 3. ) Both raw liquid acid whey and sweet condensed whey were effective PFW silage additives. The addition of condensed whey (2.7% on a dry matter basis) to PFW tended to increase the digestibility of the ensiled material, more than when no whey or or higher levels of whey were used. However, the cost of whey and i t s availability may outweigh i t s benefits in fermentation during ensiling. 4. ) PFW ensiled with barley, whey and urea was a palatable feedstuff. Rations containing 20-44% ensiled PFW were readily consumed by sheep, dairy heifers and beef cattle. 5. ) Rations containing ensiled PFW must be supplemented with crude protein, vitamins and minerals in order ensure a balanced diet. 6. ) The chemical composition of PFW was a good indicator of its nutritive value. Although both PFWs studied could be suitable feedstuffs, generally, animal performance was better with PG PFW than with K PFW. This difference was attributed to slight differences in chemical composition of the two PFW sources measured. 169 7. ) The nutritional merit of PFW lies within i t s high apparent dry matter, and acid detergent fiber digestibilities. 8. ) Weight gains, feed conversions and voluntary intakes for rations containing 22% ensiled PG PFW as measured by beef cattle were comparable to animals on a grain ration. 9. ) In terms of energy content, ensiled PFW was a suitable feed for growing-finishing animals. As a feed, ensiled PFW can be managed under feedlot conditions. 10. ) PFW may be a cheap, economical feedstuff when utilized in close proximity to a pulp mill. 11. ) Identifiable chemical contaminants including resin acids, chlorinated guaiacols, and tetra-cnlorodibenzofurans were quantified in PFW. However, no mutagenicity in the organic or aqueous fractions of the PFWs tested was detected with the Ames-Salmonella mutagenicity assay. With current technology and maintaining current pulp production levels, reducing the amount of PFW is impossible. Redirecting waste back into the mill's system and recycling the PFW into other products are alternatives to the current disposal route. The primary purpose in feeding PFW to cattle was to provide a safe, economic waste management alternative for the pulp mills, and a safe, cheap high energy feed for animal producers. 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Storage characteristics of southern pine whole tree chips in Complete utilization of southern pine. C.W. McMillin, ed. Forest Products Research Society. Madison, Wis. Stalling, D.L., Petty, J.D., Smith, L . M . , Rappe, C. and Buser, H.R. 1982. Isolation and analysis of polychlorinated dibenzofurans in aquatic samples in Chlorinated dioxins and related corrpounds. D. Hutzinger, ed. Pergamon Press, New York, pp. 77-85. Statistical Analysis System. 1985. SAS user's guide: Basics. SAS Institute, Inc., Cary, N.C. Statistical Analysis System. 1985. SAS user's guide: Statistics. SAS Institute, Inc., Cary, N.C. Thivend, P. 1977. Use of whey in feeding ruminants with particular reference to pollution problems. World Anim. Rev. 23: 20. Van Aggelen, personal communication. Van den Berg, M., Van der Wielen, F . W . M . , Olie, K. and van Boxtel, C.J. 1986. The presence of PCDDs and PCDFs in human breast milk from the Netherlands. Chemosphere 15(6): 693-706. Van Keulen, J. and Young, B.A. 1977. Evaluation of acid-insoluble ash as a natural marker in ruminant digestibility studies. J. Anim. Sci. 44(2): 282-287. Van Soest, P.J. 1969. Composition, maturity and nutritive value for forages. Adv. Chem. Ser. 95: 262. Van Soest, P.J. 1982. Nutritional ecology of ruminants. O & B Books, Orvallis, Oreg. 181 Van Soest, P.J. 1963. Use of detergents in the analysis of fibrous feeds: II. A rapid method for the determination of fiber and lignin. J.A.O.A.C. 46: 826. Van Strum, C. and Merrell, P. 1987. No margin of safety: a preliminary report on dioxin pollution and the need for emergency action in the pulp and paper industry. Greenpeace USA, Inc. Tidewater, Oregon. Vetter, R.L. and Van Glan, K.N. 1978. Abnormal silages and silage related disease problems in Fermentation of silage - a review. M.E. McCullough, ed. National Feed Ingredients Assoc. West Des Moines, Iowa. Walden, CC. and Howard, T.E. 1981. Toxicity of pulp and paper mill effluents - a review. Pulp Paper Can. 82(4): T143-T148. Walden, C C and Howard, T.E. 1977. Toxicity of pulp and paper mill effluents - a review of regulations and research. TAPPI 60(1): 122-125. Waldern, D.E. 1971. A rapid micro-digestion procedure for neutral and acid detergent fiber. Can. J. Anim. Sci. 51: 67. Westing, A.H. 1978. Ecological consideration regarding massive environmental contamination with 2,3,7,8-tetrachlorocliberizo-para-dioxin in Chlorinated phenoxy acids and their dioxins. C. Ramel, ed. Ecol. Bull. 27: 285-294. Whitlock. J.P. 1987. The regulation of gene expression by 2,3,7,8-teracnlorodlbenzc^p-cUoxin. Pharmacol. Rev. 39(2): 147-161. Wilkins, R.J., Hutaiiinson, K.J., Wilson, R.F., Harris, C.E. 1971. The voluntary intake of silage by sheep. I. Interrelationships between silage composition and intake. J. Agr. Sci. 77: 531. Wilkins, R.J. and Wilson, R.F. 1970. Silage fermentation and feed value. The British Grassland Society's Meeting. Grassland Research Institute, Hurley, Maidenhead, Berks. Williamson, P., ed. 1987. Pulp and paper Canada annual and directory. Southam Business Publications, Westmount, Quebec. Woods, W. and Burrough, W. 1962. Effect of whey and lactose in beef cattle rations. J. Dairy Sci. 45: 1539. Woolford, M.K. 1984. The Silage Fermentation. Marcel Dekker, New York. Yokoyama, M.T. and Johnson, K.A. 1988. Microbiology of the rumen and intestine in The ruminant animal: digestive physiology and nutrition, D.C. Church, ed. Prentice Hall, Englewood Cliffs, New Jersey. Zabik, M.E. and Zabik, M.J. 1980. Dioxin levels in raw and cooked liver, loin steaks, round, and patties from beef fed technical grade pentachlorophenol. Bull. Environ. Contam. Toxicol. 24: 344-349. Zagar, John. Environmental Officer, Weyerhaeuser Canada, Kamloops, B.C., personal communication. APPENDIX A l VOLATILE FATTY ACIDS ANALYSIS 182 For volatile fatty acid analyses pulp mill fiber waste silage and effluent samples were prepared according to the following procedure. Liquid effluent samples ]_ were gravity filtered. Distilled water was added to the solid samples (2:1) and the mixture was equilibrated in a closed container for 24 hr. The wet PFW mass was strained through cheese cloth, and the moisture was manually squeezed from the PFW. Modifying the procedure of Erwin et al . (1961), liquid aliquots from both the effluent and wet PFW fractions were deproteinized with zinc sulphate (0.5 N) and sodium hydroxide (0.5 N), centrifuged at 25,000 G for 20 min, decanted and stored at -20°C until analysis. Supernatants were analysed for volatile fatty acids by gas chromatography (GC). A i d sample which had been acidifed with ortho-phosphoric acid and filtered through a C-18 Cartridge Sep-pak (Waters Associates, Milford, Massachusetts, 01757), was injected onto the column of a Varian Vista 6000GC. The GC was fitted with a split-splitless capillary injector, flame ionization detector and Varian 8000 autosampler (Varian Instruments Group, Walnut Creek, CA). A J&W fused, DBWax, 15 m, 0.526 mm ID s i l i c a megabore column (J&W Scientific, Folsom, CA, 95630) with a 1.0 can film thickness was used for a l l analysis. Operating conditions were: injector temperature, 200°C; ion temperature 250°C; oven temperature i n i t i a l l y held at 110°C for 5.0 min, then increasing by 5°C per min to a final temperature of 125°C held for 5.0 min. Helium carrier head pressure was 0.35 kg/cm2, the split flew was 27 ml/min and flew rates of the hydrogen and air were 30 and 340 ml/min respectively. 1 - Adjusting the pH of the sample prior to gravity filteration was shown not to be c r i t i c a l with PFW effluent. The presence of volatile fatty acids as salts, i f any, did not affect the overall concentration of the VFAs extracted. 183 The volatile fatty acids were identified by comparison with standards made from stock solutions. Data acquisition and calculations of results were performed by a Vista 402 data system (Varian Instruments Group, Walnut Creek, CA). A P P E N D I X A2 C O M P A R I S O N O F T H E R E C O V E R Y O F V O L A T I L E F A T T Y A C I D S I N S A M P L E S U S I N G S T E A M D I S T I L L A T I O N W I T H T H E M A R K H A M S T I L L , A N D D I R E C T I N J E C T I O N T H R O U G H S E P - P A K F I L T E R S O N T O T H E G A S C H R O M A T O G R A P H Routine analyses of volatile fatty acids from rumen and silage samples can involve the separation of volatile acids by steam distillation, preparation of their sodium salts, liberation of the free acids, and extraction of acid into an organic solvent before quantification on gas-liquid chromatography (Gilchrist Shirlaw, 1967; Analyses of Agricultural Methods, 1973). Methods have been adapted to increase the sensitivity and reliability with which volatile fatty acids can be determined on the gas chromatograph. Erwin et al . (1961) showed that when 25% metaphosphoric acid was added to strained rumen fluid, allowed to stand for 30 min and centrifuged at 3000 rpm for 10 min, the supernatant could be analyzed directly by the GC. However, to maximize the sensitivity and accuracy of the column of the GC, the injected solution must be as pure as possible. In this experiment, steam distillation as a method of extracting VFAs from solution was compared with the use of Sep-Paks as a f i l t e r . VFA concentrations were determined on the GC under the conditions described in Appendix Al. 184 Prepared standards from VFA stock solutions were distilled at 1-2 ml/min using a Markham s t i l l . In addition, this prepared standards were injected directly onto the GC via a C-18 Cartridge Sep-Pak (Waters Associates, Milford, Massachusetts, 01757). Differences in the recoveries of the individual acids were tested with analysis of variance. Paired t-tests were used to determine differences between the theoretical concentration of VFA injected and the actual measured concentration. When the distilled solutions were analyzed on the GC, the recoveries of the individual acids ranged from 2.31-2.61% (Table Bl). However, the recoveries of VFAs using the direct injection via a Sep-Pak ranged between 96.45-106.49%. In this latter method, no difference (P < 0.05) between the theoretical and measured concentrations were detected. Table Al Recoveries (%) of volatile fatty acids after steam distillation using the Markham s t i l l SAMPLE ACETIC ACID PROPIONIC ACID BUTYRIC ACID 1 2.921 2.79 2.61 2 2.72 2.58 2.40 3 2.19 2.05 1.92 AVERAGE 2.61a2 2.47a 2.31a standard error 0.32 0.34 0.35 1 - mean values of duplicated samples 2 - within a given row, values with different letters differ significantly (P < 0.05) 185 Table A2 Direct injection of a sample via a Sep-Pak f i l t e r onto the gas chromatograph VOLATILE INJECTION MEASURED % RECOVERY FATTY ACID CONCENTRATION CONCENTRATION ACETIC ACID 349.44 a 1' 2/ 3 337.04 ± 39.35 a 1' 4 96.45 PROPIONIC ACID 268.08 b 285.48 ± 32.59 b 106.49 BUTYRIC ACID 217.36 c 219.44 ± 26.86 c 100.96 1 - concentration i s expressed as micromoles per m i l l i l i t e r 2 - within a given row, values with different letters are significantly different (P < 0.05) 3 - theoretical concentration of the actual concentration is based on the dilution of standard stock acids 4 - mean of three samples analyzed in duplicate by the gas chromatograph The use of Sep-Paks to extract VFAs from solution showed high recoveries and improved accuracy over the steam distillation method. Since only standard solutions were measured, the efficiency of the Sep-Paks to f i l t e r any extraneous compounds (such as sugars in the PFW silage supernatants) and to avoid contamination of the column i s not known. 186 A P P E N D I X B T H E U S E O F A C I D I N S O L U B L E A S H A S A M A R K E R T O P R E D I C T D R Y M A T T E R D I G E S T I B I L I T Y O F P U L P M I L L F I B E R W A S T E S I L A G E R A T I O N S The usefulness of ALA as a marker for estimating dry matter digestibility (DMD) in monogastrics and ruminants was reviewed by El Hag and El Hag (1983). However, the use of AIA was restricted to hays and grains rations. In certain feeds (ie. alfalfa hay), AIA is a poor method of estimation of DMD due to the magnitude of analytical error associated with the absolute amount of AIA in the sample (Van Keulen and Young, 1977). In this experiment, acid insoluble ash (AIA) as a natural internal marker was compared with total fecal collection to determine the usefulness of the former in estimating DMD coefficients of PFW silage rations in ruminants. In addition, an appropriate recovery rate of AIA in sheep fed PFW silage rations was determined. Reported recovery rates of AIA were shown to have large variations depending on feed composition and species of animal used in testing (El Hag and El Hag, 1983). In this comparison of procedures a total of six pregnant ewes were used, three animals in two periods. A randomized complete block design was used, isolating method and period effects. All animals were fed PG PFW barley-whey silage, prepared with 2.5% whey on a dry matter basis. Details of silage and ration preparation, and the digestibility t r i a l are given in Chapter 9.0. During the last six days of each feeding period, feed, ores and feces were weighed and sampled. Samples were analysed for AIA according to the 2 N HCl procedure used by Van Keulen and Young (1977). The recovery of AIA in the PFW silage rations when fed to sheep was 74.56%. This recovery value was smaller than that reported by Van Keulen and Young (1977) for legume-grain rations fed to sheep (89.6-104.9%). El 187 Hag and El Hag (1983) also reported very high recovery values (105-164%) with sheep and goats on high concentrate rations. Table Bl shows that the range of AIA content of the feed with i t s standard error was 1.59-3.59% ± 1.27. However, the mean AIA content in the feces had a smaller standard error value (0.07). Once the rations were dried and ground, the PFW had a tendency to separate out from the rest of the mixture. The large standard error in the AIA content of the feed reflected the difficulty in sampling. This error carried over in the calculation of the DMD. The mean DMD in the AIA method was 63.69%, while the mean DMD in the total collection method was 62.29%. No significant difference in DMD was detected between the two methods. The results reported herein corroborate the conclusions of Van Keulen and Young (1977) and El Hag and El Hag (1983). Table Bl Mean dry matter digestibility coefficients (DMD) of pulp mill fiber waste silage as determined by total fecal collection (FC) and by acid insoluble ash (AIA) as a natural internal marker ANIMAL %AIA IN %AIA IN %RECOVERY3 DMD4 DMD FEED FECES OF AIA (AIA) (FC) 1 3.071 3.35 79.50 72.86 60.23 2 1.59 3.59 74.48 32.99 65.57 3 2.88 3.45 76.29 63.69 62.75 4 3.42 3.44 77.29 76.84 61.44 5 3.59 3.10 67.66 78.35 62.17 6 2.60 3.27 72.17 57.38 61.57 AVERAGE 2.86 3.37 74.57 63.69a2 62.29a standard error 1.27 0.07 1.71 6.96 1.81 1 - mean of a composited sample from 6 days, analysed in duplicate 2 - within a given row, values with different letters differ significantly (P < 0.05) 3 - RECOVERY = f%AIA IN FECES X DM WEIGHT OF FECES) * 100 (%AIA IN FEED * DM CONSUMED) 4 - DIGESTIBILITY = %RECOVERY * (%AIA IN FEED) (%AIA IN FECES) 188 AIA in PFW silage rations occurred in readily measurable levels. Because of sampling variation, a thorough mixing of the ground samples, and a large number of samples from feed are recommended to increase the precision and accuracy of the estimated values. In conclusion, where total collection is not feasible, the digestibility of PFW silage rations can be predicted using AIA as a natural marker. 

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