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The use of dehydrated grass in rations for early weaned lambs and some physiological effects of a rapid… France, Robert Thomas 1975

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THE  USE  EARLY  OF  D E H Y D R A T E D GRASS IN  WEANED LAMBS  EFFECTS  OF  A N D SOME  A RAPID  RATIONS PHYSIOLOGICAL  RATION C H A N G E O V E R .  by  ROBERT B.  Sc.  Agr.,  A THESIS THE  THOMAS  University  SUBMITTED  In  the  British Columbia,  IN PARTIAL  REQUIREMENTS MASTER  FOR OF  THE DEGREE  of  BRITISH  September,  OF  OF  SCIENCE  conforming to  UNIVERSITY  1970  FULFILMENT  Department of Animal  accept this thesis as  The  of  FRANCE  1975.  Science  the  required standard.  COLUMBIA  In presenting this thesis in partial  fulfilment  of the requirements for  an advanced degree at the University of B r i t i s h 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 representatives.  It  is understood that copying or publication  of this thesis for financial gain shall not be allowed without my written permission.  Department of  Animal Science  The University of B r i t i s h Columbia  2075 Wesbrook P l a c e Vancouver, Canada V6T 1W5  Date  ,/}{Jd/7S  ABSTRACT  A study was conducted to evaluate dehydrated grass pellets (Orchard grass — Ladino clover) as a feed for early-weaned lambs. Three groups of 8 Polled-Dorset lambs were weaned at 8 weeks of age and were fed either a) the dehydrated grass, b) a 50-50 mixture of the grass and protein-supplemented barley or c) a protein-supplemented barley ration. All rations were pelleted. Digestibility trials were also conducted and the effect of level of feed intake on nutrient digestibility investigated.  The dehydrated grass resulted in rates of gain comparable to those produced by the pelleted barley ration. Feed conversion efficiency was lowest for the grass and highest for the barley ration. An interaction between the dehydrated grass and barley was observed in nutrient digestibility. Increasing the level of feed intake from approximately maintenance to appetite tended to result in slight depressions in the digestibility of energy and protein of all rations.  It may be concluded from this experiment that dehydrated grass can be used successfully for intensive feeding of early weaned lambs and little nutritional advantage appears to be gained from combining dehydrated grass with barley. A second study was undertaken to measure the changes occuring in five parameters when the ration of lambs was rapidly changed from all-roughage to all-concentrate. The five parameters were blood plasma glucose, rumen lactate concentration, rumen ammonia level, rumen protozoa population and rumen pH.  The main effect of the change over from roughage to concentrate was the accumulation  of lactic acid in the rumen. This accumulation resulted in a lowered  - iii -  rumen pH and a decrease in protozoa numbers. During the change over an initial increase in rumen ammonia level was followed by a decline in this  parameter.  It is postulated that this may have been due to the increased nitrogen intake and a subsequent adjustment  in the rumen microbe population leading to increased  ammonia utilization. An increase in plasma glucose level was observed which was probably due to one of two factors, either the availability  of lactate as a  carbohydrate source in the rumen or to glucose formed by hydrolysis of starch in the intestine.  From the latter part of the study it may be concluded that when  ruminant  rations are changed from high roughage to high concentrate the change should be slow enough to prevent a large accumulation of lactic acid. This would mean a period of 3 to 4 weeks under normal circumstances.  TABLE OF  CONTENTS Page  INTRODUCTION  1  LITERATURE  2  a:-  REVIEW DRIED GRASS FEEDING  2  THE ROLE OF DEHYDRATED IN RUMINANT RATIONS  FORAGES 3  THE USE OF DEHYDRATED FORAGES IN DAIRY CATTLE RATIONS  b:-  THE USE OF DEHYDRATED BEEF CATTLE RATIONS  FORAGES  THE USE OF DEHYDRATED IN SHEEP RATIONS  FORAGES  4 IN 5  6  THE EFFECTS OF PROCESSING ON THE NUTRITIVE VALUE OF DEHYDRATED FORAGES  6  THE EFFECT OF DRYING PROCESS ON NUTRITIVE VALUE OF GRASS  8  THE EFFECT OF TEMPERATURE OF DRYING ON NUTRITIVE VALUE OF GRASS  9  THE EFFECT OF PHYSICAL FORM OF DRIED FORAGE ON ITS UTILIZATION  10  THE EFFECT OF COMBINING OTHER FEEDS WITH DRIED GRASS  10  THE EFFECT OF FORAGE ON RUMEN pH  13  RATION CHANGEOVER  PROCESSING  EXPERIMENT  13  LACTIC ACIDOSIS  13  RUMEN AMMONIA LEVELS  19  -  T  -  Page RUMEN PROTOZOA  22  RUMEN pH  23  PLASMA GLUCOSE  25  MATERIALS AND METHODS  27  a:-  DRIED GRASS FEEDING  27  b:-  RATION CHANGEOVER EXPERIMENT  28  SAMPLING PROCEDURES  28  ANALYTICAL PROCEDURES  31  RESULTS  35  a:-  DRIED GRASS FEEDING  35  b:-  RATION CHANGEOVER EXPERIMENT  40  AND CONCLUSIONS  50  DISCUSSION  LITERATURE CITED APPENDIX  1  56 DEFINITION OF MODULUS OF FINENESS  65  DEFINITION OF WAFERS, COBS, AND PELLETS  66  PHOTOGRAPH OF RUMEN CONTENTS  67  PHOTOGRAPHS OF RUMEN WALL SAMPLES  68  RUMEN LACTIC ACID CONCENTRATIONS  71  RUMEN AMMONIA CONCENTRATIONS  72  RUMEN PROTOZOA NUMBERS  73  APPENDIX 8  RUMEN pH  74  APPENDIX 9  PLASMA GLUCOSE CONCENTRATIONS  75  APPENDIX 2 APPENDIX 3 APPENDIX 4 APPENDIX 5 APPENDIX 6 APPENDIX  7  - vi -  LIST OF TABLES Page  TABLE  1  RATION  TABLE  2  CHANGEOVER  TABLE  3  ANIMAL  TABLE  4  DIGESTIBILITY  TABLE 5  29  COMPOSITION  30  DESIGN  PERFORMANCE  DATA  DATA  CORRELATIONS - Lactic Acid, Barley, Hay, Rumen pH, Rumen Lactate, Rumen Protozoa Numbers, Rumen Ammonia, Plasma Glucose  37  39  41  —  via —  LIST OF FIGURES Page FIGURE 1  PATHWAYS  18  FIGURE 2  CONWAY MICRODIFFUSION UNIT  34  FIGURE 3  WEIGHT CHANGE VS TIME  36  (Dried Grass Feeding)  FIGURE 4  RUMEN LACTIC ACID CONCENTRATION VS TIME  42  FIGURE 5  RUMEN AMMONIA CONCENTRATION VS TIME  44  FIGURE 6  RUMEN PROTOZOA NUMBERS VS TIME  45  FIGURE 7  RUMEN pH VS TIME  47  FIGURE 8  RUMEN pH VS RUMEN LACTATE  48  FIGURE 9  PLASMA GLUCOSE VS TIME  49  -  1  -  INTRODUCTION  The storage and handling of forage crops has always been a problem for livestock producers. The development of the hay baler, which reduced the bulk density of loose hay, helped to some degree. However, hay bales require a lot of storage space and the handling and feeding is difficult  to automate.  For these reasons high density forage cubes and  pellets have been developed. These products require less storage space and lend themselves well to automated  handling and feeding.  Another problem in forage production has been the dependence on weather conditions during harvest. Many million tons of forage are wasted annually due to rain during the field curing process. Experimental work began as early as 1905  (Oehring 1973)  on the artificial drying of forages.  Today a wide range of crops are artificially  dried in drying drums heated  with petroleum products. In the Fraser Valley region of B.C. several dehydration plants produce dried grass pellets. The majority of this product has been used in swine and poultry  rations. In  Europe there has been an increased interest  in feeding dried grass to ruminants. However, very little information is available on the feeding value of dried grass for early, weanedd lambs. Therefore, a study was undertaken to compare the feeding, v~alue of the following rations (1)  dried grass, (2)  mineral supplement, (3)  50% dried grass, 50% barley, plus a protein  barley  plus a protein mineral supplement.  When the lambs on the above rations were slaughtered rumen fluid pH's were measured. It  was noted that the pH of the rumen fluid of the  lambs on the straight dried grass ration was one full that of those on the other two  pH point higher than  rations. After studying the literature it was  decided to undertake a second trial to study the effects of switching a  -  lamb's ration from straight  2  -  roughage to straight concentrate. Five parameters  were measured during this changeover. The parameters were blood plasma glucose, rumen fluid tration  pH, rumen protozoa population, rumen ammonia concen-  and rumen lactic acid levels.  LITERATURE a:-  DRIED  REVIEW  GRASS FEEDING  Connell (1971) stated that technically the artificial is a most efficient crop. Patrick  value of the fresh  (1967) noted that dried green crops can yield 50% more  energy and 300% Hee further  route to conserving the high nutritive  drying of grass  more protein per acre than a two ton crop of barley.  stated that dehydration results in higher yields than other con-  servation processes because of the low nutrient (1967) stated that with efficient  losses that occur. Christensen  operation these losses will not exceed 3%,  even when losses occuring before the crop enters the dryer are considered. This figure compares very favourably with losses, frequently the feeding value, encountered in hay or silage. (Tarrup  over 30% of  Unidry 1973).  Smith and Moeller (1973) stated that the trend toward  mechanized  feeding systems is creating a demand for "roughage" products in a form which can be stored in bulk and can be handled through conventional conveying equipment.  Pelleted dehydrated forages would meet these requirements.  Therefore, it would appear that from the point of view  of quality  of feed  and ease of handling pelleted dehydrated forages have merit. From a nutritional Forage Drying (Shellstar  point of view dehydrated grass is quite valuable.  1973)  listed the average analysis of dehydrated •  grass as follows: Crude Protein  -  13-22%  Dry  -  62-68%  Matter Digestibility  -  3  -  Similar figures were given by Connell (1971). He stated that the average dry matter digestibility  of dehydrated grass was 65% with the range being 60 to  Dried green crops are rather  70%.  poor sources of some major and trace  minerals and this must always be considered when including dried crops in rations. (Forage Drying - Shellstar  THE  1973)  ROLE OF DEHYDRATED  FORAGES  IN  RUMINANT  RATIONS  Having outlined that dehydrated grass is a desirable feed for ruminants the next step is to determine how it "fits"  into the ration. Raymond (1967)  stated that insisting a feed stuff such as dried grass be a complete feed may be impractical. He suggested that perhaps a better use would be to supply certain nutrients to a mixed ration. Raymond (1968) further stated that all livestock enterprises in Britain have access to "fibrous feeds", such as hay, silage or straw. These can provide the basic "fibre" a partial  in the rations, dried grass is then used as  or complete substitute for the concentrate part of the ration. As well  as high digestibility  (energy), dried grass can have a high protein content and so  can balance the low protein content in "fibrous feeds". It  has been claimed that  providing the physical form is acceptable, all classes of stock will eat dehydrated grass, high intakes can be achieved with productive animals. Recent research has shown that dried grass may have a higher feeding value than analysis of crude protein and digestibility would suggest. (Forage Drying - Shellstar  1973)  Tayler (1969) stated that the major requirements of dried grass are high digestibility, adequate protein content and a modulus of fineness close to 1. (Appendix  1)  He also felt that a proportion of long forage or roughage was desirable as a means of maintaining good health in animals fed processed dried grass. He stated  further  that  economic  considerations  indicate  that  -  4  -  dried forage should be regarded as a concentrate supplement to grazed or ensiled feeds, which supply nutrients at lower unit costs, rather than as the sole feed. Oehring (1973) suggested that the greatest opportunities for expanding the market for dried green crops was likely to be in direct feeding of ruminants rather than in the production of compound feeds. Blaxter (1973) stated that in assessing the economic worth of dried forages energy value will prove a more important  THE  USE OF DEHYDRATED  criterion than crude-protein or carotenoid content.  FORAGES  IN DAIRY  CATTLE  RATIONS  Connell (1971) reported that 2.27 kg (5 lbs) of dried grass cubes (milled) effectively  replaced 1.83 kg (4 lbs) of balanced dairy  cubes, as a  supplement to hay, during the first twenty weeks of the lactation of Holstein — Friesian cows. He further  reported production levels of 32 kg  (70 lbs) per day from dairy cattle fed solely on dried grass. Forage Drying (Shellstar 1973) stated that as a concentrate replacer, dried forage can be fed to dairy cattle as a production ration to support milk  production up  to 23 kg per day. They suggested rates of 2.27 kg of 16% crude protein and 65% digestibility dried grass or 2.04 kg of 20% crude protein and 70% digestibility dried grass per 4.54 kg of milk. Tayler and Aston (1973) found, that as a supplement fed with grass silage, straight dehydrated grass was equal to a grass-barley mixture barley-protein mixture.  Khalifa et al  or a  (1970) found no difference in production  of cows fed three combinations of pelleted dried grass and barley concentrate. The three combinations were 75:25, 50:50 and 25:75.  Gordon and Mcllmoyle (1973) reported a replacement value of 1.08:1 for dried grass and concentrates as supplements to silage. In trials where dried grass and grain were compared as a supplement to grass silage they found that dried grass increased silage intake over the intake when grain was fed. Therefore, even though a grass-concentrate pellet was of lower  -  5  -  digestible energy concentration than a straight concentrate pellet the increased silage intake allowed for similar production. In further  work  Gordon and  Mcllmoyle (1973) showed that diets of dried grass wafers with low amounts of straw and a mineral supplement were capable of sustaining milk  production of  about 25 kg per day.  Ostergaard and Neimann-Sorensen (1973) have shown that dried grass can substitute for traditional  roughage and for concentrate without any marked  changes in milk production.  Waldern (1973) reported that high levels of dehydrated grass (56% of total DM intake),  of the quality  used (21.2% crude protein),  can replace corn  silage and grass hay in the diets of lactating cows and satisfactorily  maintain  high levels (23 to 25 kg FCM) of milk  milk  production without altering  composition.  Body weight trials. weight  THE  changes were recorded in several of the above mentioned  It does not appear that these levels of production are accompanied by loss when dry grass is fed.  USE OF DEHYDRATED Londsdale et al  FORAGES  IN BEEF  CATTLE  RATIONS  (1971) compared straight grass wafers with wafers plus  50% rolled barley. They found dry matter intake and live weight gains to be similar on all diets. However, carcass weight gain was significantly higher for animals given wafers containing barley.  It  is stated  in Forage Drying (Shellstar  1973) that for young calves (dairy  or beef) dried forage may be fed free choice. Compared with normal hay and concentrate rations, there appears to be considerable benefit of calves.  in health and appearance  -  For fattening cattle  6  -  Forage Drying (Shellstar  1973) recommends a 2:3  ratio of high quality dried forage: mineralized rolled cereal, fed in conjunction with a basic roughage.  Tayler (1973) reported that cattle fed pellets of dried grass as a supplement with basal grass (silage in winter and pasture in summer) did as well as cattle fed a barley supplement over an eighteen month feeding period.  However, Coleou (1973) reported that exclusive use of dried grasses, fed alone or in combination with legumes, seldom gives either adequate daily gain or a sufficiently finished animal unless the slaughtering age is postponed.  THE  USE OF DEHYDRATED  FORAGES  Although little information grass to lambs for fattening  IN SHEEP RATIONS  is available regarding the feeding of dehydrated  Forage Drying (Shellstar  1973) states that dried grass  can be fed to in-lamb ewes with quite satisfactory results. They recommend feeding up to 1.35 kg per head per day with up to .68 kg of rolled oats.  THE  EFFECTS OF PROCESSING ON THE NUTRITIVE  DEHYDRATED  VALUE OF  FORAGES  Londsdale et al (1971) found that coarse milling compared to chopping reduced the apparent digestibility energy. Wilkins et al  of dry matter, organic matter, cellulose and  (1972) found that the digestibility  of organic matter  and cellulose decreased with a decrease in modulus of fineness (more fine particles) and this was associated with more rapid passage of the finely-milled through the alimentary in digestibility  tract.  material  Milne and Campling (1972) found only small differences  of organic matter, retention  of nitrogen and loss of energy in the  urine between alfalfa cobs and alfalfa pellets. However, the digestibility of crude fibre decreased with decreasing particle size.  -  7  -  Thomson (1971) comparing chopped alfalfa with ground and pelleted alfalfa found that the processing significantly depressed the disappearance of apparent digestible energy prior to the small intestine and significantly increased that occuring in the small intestine.  Wainman et al nutritive  (1972) showed that grass pellets have a greater  value per unit weight than has long unprocessed material. Except  for the poorest quality feed, but it markedly  material, pelleting reduced metabolizable energy of the increased the net availability  for production, and the latter effect was of greater The net availability  of metabolizable energy magnitude than the former.  of metabolizable energy for production was 52% for pellets  and 40% for long nraterial. Blaxter  (1973) reported that pelleting depressed the  metabolizable energy of high quality  dried forages, but tended to increase that  of very low quality  ones. Van Es and Van der Honing (1973) stated that  the higher fecal energy loss of pelleted forages is only slightly compensated for by smaller energy losses in methane or urine. However, a large compensation results from the better utilization  of the metabolizable" energy of pelleted rations.  They conclude that the net energy content of ground and pelleted forage is approximately equal to' the net energy content of the original material.  Wilkins (1973) explained the more efficient  use of energy in ground  roughages compared to long roughages by the following:— reduced expenditure of energy in eating and ruminating, reduced loss of methane and less heat production in the rumen and alteration  in the products of rumen  fermentation  (i.e.  acetate levels lower when ground forages fed). The overall effect  two  phenomena (reduced digestibility and increased efficiency)  roughages.  of the  varies among  -  8  -  Tayler (1969) found that milling of dried grass increased I iveweight gains over the same grass fed in a long form. This increased gain was associated with increases in voluntary  Wallenius et al  intake  of processed grass.  (1966) disagreed with many of the above authors.  They felt that the reduced cellulose digestibility dehydrated alfalfa  of finely ground pelleted  made it an undesirable feed for ruminants. They reported  cellulose digestibility^ values of 52.6%  in one experiment  and 37.2%  in another  when ground pelleted dehydrated alfalfa was fed. This was compared with cellulose digestibility  THE  EFFECT  70.5%  when long alfalfa hay was fed.  OF DRYING  PROCESS ON NUTRITIVE  VALUE  OF GRASS  Thomson (1971) found that when fresh and dried grass were compared the overall digestion of energy did not differ different.  but the site of digestion was  When dried grass was fed less of the apparently  digested energy  disappeared prior to the duodenum and significantly more in the passage through the small intestine. did not differ  He also found that although overall nitrogen digestibilities  the amount of nitrogen entering the small intestine was markedly  higher in the dried compared to the wet grass.  Ekern et al  (1965) reported that the metabolizable energy of fresh  grass was 4% greater than that of the same grass dried (60.92 kcal/100 ingested vs 58.22 kcal/100 the  kcal ingested). However, the heat production from  metabolizable energy of fresh grass was on average 16% greater  of the same grass when artificially energy retention  kcal  than that  dried. The overall result was that the  observed when dried grass was given was greater than when  grass was given in the fresh state.  -  9  These authors also reported a greater nitrogen absorption when fresh grass was fed. They felt the low absorption of nitrogen from dried grass was probably related to denaturation  of the grass protein by heat and to  lowered absorption of nitrogen as ammonia. Sheep given fresh grass excreted j!5%  less nitrogen in the feces and 11% more in the urine than those given  dfried grass. No differences occured in nitrogen retention.  Ekern et al  (1965) stated that their experiments provided evidence that  the bacterial and digestive processes in ruminants given fresh grass and dried grass differ. The energy of fresh herbage was digested better than that of the dried, and more nitrogen was apparently absorbed, to be excreted in the urine. These and other observations indicated a more active and rapid  fermentation  process in the sheep given fresh grass.  Blaxter  (1973) reported that several experiments have shown that  dehydration increases the nutritive  value of a crop slightly. Both apparent  digestibility and metabolizable energy are depressed by drying the crop, but the efficiency with which the metabolizable energy of the dried crop is used is enhanced, the animals producing slightly less heat when fed the dried rather than fresh material. The net effect of the material  THE OF  EFFECT  is a very small 3-4% increase in the value  as an energy source to the animal.  OF TEMPERATURE OF DRYING ON NUTRITIVE  VALUE  GRASS larrige et al  (1973) reported that high temperature  in a slight decrease in apparent digestibility  of organic matter and a 5-10 unit  decrease in crude protein digestibility, (inlet temperature temperature  90-115"C)  dehydration resulted  700-900°C  outlet  Israelsen (1973) reported that excessive drying may reduce  the net protein utilization  to nearly zero.  -  THE  EFFECT  10  -  OF PHYSICAL FORM OF DRIED  FORAGE ON ITS  UTILIZATION Raymond (1968) stated that present evidence suggests that the optimum package for utilization by ruminants may be a fairly directly from  large pellet, produced  unmilled dried grass, but containing a portion of small particles.  Tayler and Aston (1973) reported that when dried grass was offered to dairy cattle as wafers, cobs or pellets (Appendix 2) with grass silage, the cattle receiving pellets ate 6% more silage and produced 19% more milk than those receiving cobs or wafers. These authors concluded that when dried grass is given as a concentrate supplement to silage fed ad libitum the dried grass should be in pellets of low modulus of fineness. Tayler (1969) found that the intake of dried grass increased as the proportion of fine particles in the feed increased. He also reported that the hardness of pellets was an important  consideration. If  pellets were too hard  (unit density in excess of 1.lg/cc), young cattle ate even less than the same material  in chopped form. He also found that if the package was too  easily broken and was dusty, the full  potential  intake was not achieved. He  reported that when dried grass was fed ad libitum  as a sole feed, and  excessive hardness or dustiness were avoided the highest intake by ruminants was obtained when the grass had been ground in a hammer-mill with screens of about 2 to 4 mm.  THE  EFFECT  OF COMBINING  OTHER  FEEDS WITH DRIED  GRASS  German workers in the late 19th century demonstrated that added starch decreased the digestibility of other nutrients of hay. Armsbyi' (1917) termed this phenomenon "depression of digestibility" since potential digestible matter escaped digestion. This "depression" was particularly  manifested by  feeds containing large amounts of soluble carbohydrate. He reported that the dry matter digestibility of hay may be reduced by as much as 12%  -  11  -  when these feeds are included in the ration.  Forbes (1933) stated "an individual foodstuff expresses its normal and most characteristic nutritive  value, for a given kind of animal, under specified  conditions governing nutritive  requirements, only as it is a part of a ration  which is qualitatively  complete and quantitatively  sufficient, for conditions  existing." He further  emphasized that feedstuffs cannot be properly evaluated  individually as the net energy values of individual foodstuffs are fundamentally variable when in different  combinations in a ration.  Kromann (1973) reported that the associative effects of feeds may be manifested at any one or all levels of metabolism (digestion, absorption and cellular metabolism)  and stated: "The interactional  effect  at the digestive level  is well known and this was thought to be the only level of metabolism influenced by interaction  of feeds within a ration. The decreased utilization  of fibre as  influenced by soluble carbohydrates in ruminants is perhaps relatively  simple to  explain since the micro-organisms use the most readily available carbohydrate as an energy source. These soluble carbohydrates are not available per se to the microorganisms but are hydrolyzed by enz ymes secreted by them. Hydrolysis releases the simple sugars which the microorganisms utilize as an energy source. Similarly, there are hydrolytic enzymes in the digestive tract. These enzymes hydrolyze the soluble carbohydrates, proteins and fats to their  respective simple  units which can then be absorbed. As explained by the Law of Mass Action the less complex substrates are more likely  to come in contact with hydrolytic  enzymes than the complex substrates. Sucrose would have more reacting than an equal weight  material  of starch. Thus, more monosaccharide would be hydrolyzed  from sucrose than starch per unit time; subsequently absorption as well as metabolism would be influenced."  -  Londsdale et al  12  (1971) found that the inclusion of 50% barley with  chopped or coarsely ground grass increased the overall digestibility matter  but reduced the digestibility  of organic  of cellulose.  Tayler (1969) reported that the inclusion of 50% barley  in wafers  increased the rate of gain by only 8% compared to a response to milling alone of 5%. In view of the difference in the estimated net energy values of dried grass and barley this indicated a nutritional  interaction between the two  components of the wafer.  Londsdale et a[ (1971) stated that the reduction in gut fill, when barley grain was added to a roughage feed, masks any increased rate of gain which may occur in body tissues. Therefore, when doing feeding trials to compare dried grass with barley-dried grass mixtures carcass weight gain should be measured, as differences in gut fill  may mask differences in weight  gain.  Forbes et al barley  (1967) reported that supplementing grass intake with  increased total dry matter  centrates increased total intake  intake. Greenhalgh (1973) stated that con-  of long grass but reduced total intake when  included in pellets.  McCullough (1972) reported that the supplementation of grass silage with dehydrated grass was superior to supplementation with barley. As the metabolizable energy concentration of rolled barley appears to be higher than that of dried grass this author concludes that the apparent higher value of dried grass in this experiment  nutritive  is probably due to the better associative  effect between the silage and dried grass than between the silage and rolled barley. His results suggested that 1.12 kg of dried grass was equivalent to 1.80 kg  -  13  -  of rolled barley as a supplement for silage. This underlines the point made earlier that the feeding value of a feedstuff  obtained by feeding it alone to  ruminants is of little use in practical nutrition.  THE  EFFECT  OF FORAGE  PROCESSING ON RUMEN pH  Ground roughages lead to lower rumen pH than long roughages. Wilkins (1973) stated that rapid feed consumption coupled with the low level of rumination when ground diets are fed tends to reduce the quantity  of saliva  secreted. He also noted that rumen V F A levels increase more quickly after feeding when ground roughage is fed, due to rapid consumption resulting in larger quantities  of feed arriving in the rumen in a short period of time.  These two factors combine to yield reduced rumen pH levels when ground roughage is fed.  b:-  RATION CHANGEOVER EXPERIMENT  LACTIC ACIDOSIS Ruminants not accustomed to a grain diet often suffer acute digestive disturbances and in many cases death, within twenty-four of a large quantity Ahrens 1967;  of grain (Hungate et al  Brawner et al  symptoms of this disorder. In  hours after consumption  1952; Gilchrist and Clark  1957;  1969). Rumen atony and loss of appetite are many cases reported in the literature these  symptoms have been induced by rather  unnatural  methods (ie. not likely to  occur in practical feeding situations). For example, the animals are held without feed for twenty-four  hours and are then allowed to engorge themselves with  grain (Ahrens 1967)  or the carbohydrate source is added directly to the rumen  by way of a rumen fistula (Hungate et al usually cause acute acidosis and death. In  1952). These drastic methods commercial animal feeding this very  sudden intake of grain is not likely to occur. It it  is not a major problem.  may occur accidentally but  -  14  -  Lactic acidosis may be a problem during the change from a high roughage to a high concentrate ration as could take place when animals enter a feedlot, if the change was too rapid. The ingestion of excessive amounts of carbohydrate allows for rapid fementation of the fermentation  within the rumen. The main product  is lactic acid. The normal pH of animals on roughage  rations is approximately  within the range 6.5  Thomson 1967; Ahrens 1967;  - 7.5  (Gilchrist and Clark  1957;  Browner 1969). As lactic acid accumulates, the  pH drops from^ithe'se normal levels to 3.5  - 5.0  in severe cases.  Tremere et al (1967) have reported an experiment were introduced at two different  where concentrates  rates to cattle on a hay ration. They  found that in both cases lactic acid levels increased and that the highest level of lactic acid (75  mM/litre) corresponded to the lowest pH.  The results of this increased acidity were as follows: (1)  chemical rumenitis due to the acidity;  (2)  a massive flow  of fluids into the rumen  from the body circulation caused by the increased osmotic pressure; (3)  destruction of the protozoan and bacterial flora of the rumen with the exception of the Streptococci and Lactobacilli which are the organisms carrying out the  fermentation  of the grain. (Thomson 1967).  The increased lactic acid concentration is due to a sudden bloom of Streptococcus bovis. Hungate et al  (1952) reported that the numbers of  Streptococcus bovis  diminished almost immediately  billion per millilitre  was reached and lactobacilli then predominate. Streptococcus  bovis  after the maximum  of several  readily ferments soluble carbohydrates to lactic acid. Its predominance  in the rumen would cause lactic acid to be relatively  more abundant than  -  15  -  other products.  Under favourable conditions of pH, lactic acid may be fermented to propionic acid (Phillipson and McAnally 1942;  Elsden 1945). However, the  build up of lactic acid depresses the pH to such an extent that propionic acid bacteria (for  example, Peptostreptococcus elsdenii) cannot grow.  An abundance of lactobacilli in the rumen of animals suffering from acidosis has in some instances been interpreted  as implicating lactobacilli in  the development of the acidity, but these examinations  may have been made  after the initial increase of streptococci has taken place (Perry et al  1957).  Streptococcus bovis occurs in larger numbers in hayfed ruminants than do the lactobacilli and have an extremely  rapid potential  growth  these factors permit Streptococcus bovis to piitgrow but Streptococcus bovis  rate. In  the lactobacilli  most cases initially,  is inhibited at the high acidities it causes, whereas  the lactobacilli are not. Therefore, the initial increase of Streptococcus bovis which occurs when grain is fed is followed by a great reduction of streptococci and the development of a very abundant population of lactobacilli. Hungate (1966) reported that lactobacilli are quite numerous in animals with chronic high rumen acidity.  The concensus of opinion is that the inclusion of soluble carbohydrate in ruminant  rations lowers the rumen pH. This lowered  pH is caused by  increased levels of lactic acid in the rumen. The degree of this increase appears to be related to the changeover period and the levels of grain which are fed. (Tremere et al  1967). Annison (1959) showed very similar lactic acid  accumulations when ruminant  diets were changed from hay to lush pasture.  The fate of lactic acid in the rumen appears to be open to some discussion. Jayasuriya and Hungate (1959), using isotopes, demonstrated that  -  16  -  most of the lactate gave rise to acetate in hay fed animals. This implies conversion of lactate to pyruvate and decarboxylation of pyruvate to acetate. Lactic acid is apparently an unimportant  intermediate  in the rumen fermentation  of hay-fed steers and is not a precursor of the propionate formed. If were an essential intermediate  lactate  in the production of rumen propionate, little  propionate would be expected in rumen contents of hay-fed animals. A considerable amount is usually found, arising via pathways in which lactate is not involved.  However, in the grain fed animal lactate becomes an important intermediate  and gives rise to propionate. Phillipson (1952) noted that in  corn fed lambs the fermentation  of starch in the rumen involved two stages.  The first stage leading to the formation of lactic acid and the second being a further  fermentation  fatty acids, particularly  Baldwin et al fed, the main pathway the acrylate  of the lactic acid with the production of volatile propionic acid. (Figure 1).  (1963) reported that when soluble carbohydrates were of conversion of lactic acid to propionic acid was  pathway.  The very low rate of lactate fermentation  when hay fed cattle receive  soluble carbohydrates indicates a scarcity of lactate fermenters. The result of this scarcity is the accumulation of lactic acid. By the time enough lactate has accumulated to favour lactic acid fermenters, the lactic acid production so exceeds its fermentation  that the rumen becomes acid and microflora!  growth stops before an adequate population of lactacidioves develope. With a gradual change to grain there is no excess acidity, and a balanced flora adapted to. continuous fermentation  of the new ration evolves.  -  17  -  The physiological basis for the accumulation of lactate depends on a shift  in the position of the rate limiting step in the fermentation  from  the hydrolysis of a polysaccharide to the dissimilation of a 3-carbon compound. According to information gained by the use of radioactive isotopes, lactate is not involved to any significant extent as an intermediate of roughage rations, (Eusebio et al  1959;  Baldwin et al  in the  fermentation  1963), so that  when lactate does accumulate the limiting; step is probably the  fermentation  of a compound which may act as a precursor of lactic acid but is usually converted to other  products. In  pyruvate which is greatly  all probability  it is the dissimilation of  slowed down. Instead of being converted to volatile  fatty acids, pyruvate acts as a hydrogen acceptor in the re-oxidization  of the  reduced pyridine nucleotide coenzymes generated by the breakdown of carbohydrates. (Walker 1968).  A  number of factors may be responsible for the slowing of the  conversion of pyruvic acid tomost important.  A fall  of readily fermented  volatile fatty acids and of these pH may be  in pH within the rumen accompanying the  fermentation  carbohydrate is presumably the result of an increased  production of acid materials at a rate which cannot be balanced by absorption through the rumen wall and neutralization  by bicarbonate entering  the rumen in saliva. Enzymes dissimilating pyruvic acid may be adversely affected  by the lower  pH and it  is known that the rates of production of  acetic, propionic and higher acids decline with decreasing pH below (Bruno and Moore 1962). In  addition, below pH 5.5,  in the form of carbonic acid, which in turn  bicarbonate would be  means the conversion of  to propionate would be blocked because that pathway carbon dioxide. The reducing power normally  6.0.  pyruvate  requires the fixation  of  used in the conversion of pyruvate  to propionate is then available for the reduction of pyruvate to lactate. (1968) has demonstrated this phenomenon in his work.  Walker  Hopgood (1965) demon-  strated that the rumen cellulolytic bacteria, Ruminococcus flavefaciens produced  OUTLINE FIGURE  OF VOLATILE  FATTY  18  -  ACID FORMATION  FROM  LACTATE  1 C0  2  H  2  -Acetyl-Co A 2H Acetoacetyl-CoA  Acetate  Pyruvate , ^ 2 H  -V Oxaloacetate  V2H  Lactate  k  -2H B-Hydroxybutyryl-CoA  Malate  /  H 0 2  Aery I ate 2H  ^„ o  2Hs  V Propionate-  2  X  Fumarate ATP  Succinate  Crotonyl-CoA ATPButyryl-CoA ATP Butyrate  SLATTER  AND  ESDALE  PATHWAYS HAY  FED  GRAIN  FED  ANIMALS ANIMALS  L A C T A T E - * PYRUVATE—>ACET ATE LACTATE'—> ACRYLATE—> PROPIONATE  (1968)  -  large quantities  19  -  of succinic acid when supplied with glucose and bicarbonate,  but almost entirely  lactic acid if an exogenous source of carbon dioxide was  not provided.  RUMEN AMMONIA  LEVELS  Another parameter which may be affected  by changes in rations is  rumen ammonia. Several workers have noted that rumen ammonia levels increase as the nitrogen  level in the diet .'.increases. (Annison et al  1970). This can occur when the ration  1959;  Mclntyre  is changed from poor grass hay to  grain, or from grass hay to pasture. The general explanation for this is that there is an excess of nitrogen available in the form protein nitrogen which is readily fermented  of protein and non-  to yield ammonia. Adaptation of  the microbial population to the diet causes a return to normal levels.  Reis and Reid (1959), showed that pH affected in the rumen. The "effect  of pH was most probably the result of an effect  on the enzymes concerned in deamination pH for ammonia accumulation is 6.5 in the  ammonia production  of amino acids. The most favourable  - 7.0.  The lowered levels at low pH,  presence of soluble carbohydrate, is due largely to increased utilization  for the synthesis ofnvmicrobial protein. Therefore, during a change from a poor quality  hay to a grain ration there is an initial increase in rumen ammonia  levels due to an excess of nitrogen which cannot be utilized. However, as the rumen organisms adapt to the higher nitrogen levels the rumen ammonia levels drop. After  the ration has been changed to a grain ration the rumen  ammonia levels may decline below the levels in hay fed animals due to the increased synthesis of microbial protein. Annison et al  (1954) showed that,  the amount of ammonia accumulating reduced as the level of starch was increased when: high protein supplements were fed.  -  20  -  Ammonia accumulation levels in general are the result of a balance between  rate of formation  within the rumen, rate of passage to the omasum,  rate of absorption from the rumen, and rate of uptake by microbial populations.  Purser and Moir (1966) stated that greater  protozoal  populations are  associated with higher ammonia levels. Protozoa probably produce ammonia as a by-product of endogenous metabolism (Warner 1956)  but the significance has yet  to be determined.  Calculations based on the net protein utilization bacterial  protein reported by McNaught et al  bacterial  protein to protozoal  values for protozoal and  (1954) indicated that, in converting  protein, protozoa could release as ammonia  nitrogen, 18% of the protein nitrogen involved in the conversion before the host animal would suffer a loss of available amino acid nitrogen. This was due to the higher digestibility  of the protozoal  protein as compared to 90% for  The relationship between  protozoal  protein (74%  for bacterial  protein) and higher biological value.  rumen ammonia levels and protozoa numbers  is open to some discussion. Purser and Moir (1966) reported that protozoa numbers reflect  rather  than cause variations in the accumulation levels of  ammonia. However Christiansen et al  (1965) and Klbpfenstein et al  (1966)  considered that higher ammonia levels in faunated sheep, as compared to defaunated sheep, were the result of the protozoa present in the  former.  Christiansen et al (1965) found significantly higher ammonia concentrations in faunated  lambs (12.2  mg % versus 6.4  Klopfenstein et al was greater  mg %)  as compared to defaunated lambs.  (1966) stated that protein degradation in the rumen  in the presence of protozoa, resulting in elevated rumen ammonia  concentrations.  -  21  -  There is considerable diurnal variation level is lowest immediately to 3.0  in rumen ammonia levels. The  before feeding and reaches a maximum from  1.5  hours after feeding. (Davis and Stallcup, 1967).  Leibolz (1969) stated that the increase in concentration of ammonia in the rumen liquor after feeding was dependent on the solubility of the dietary-; protein and the dietary  energy intake. The more soluble the protein  the higher the ammonia concentration.  Pearson and Smith (1943) reported that starch stimulated synthesis of protein in rations containing urea. Annison (1956) showed that the rates of disappearance of ammonia and amino acids from the sheep rumen after the feeding of casein were increased in the presence of carbohydrate. It is likely  that there is a stimulation of synthetic reactions that involve an increased  utilization  of ammonia when ' carbohydrate is present.  One of the most interesting problems in rumen ecology is the extent to which ammonia serves as the nitrogenous material for the synthesis of microbial cells. Many of the rumen bacteria assimilate ammonia in preference to amino acids and for some it  is essential (Bryant  Ammonia is probably relatively  and Robinson 1963).  more important  for the nutrition  of  the fibre digesting bacteria than for those utilizing starch or soluble sugars. Immediately after forage is ingested, both soluble carbohydrate and soluble proteins are present/Digestion of the  proteins is rapid, with release of at least  small concentrations of amino acids which may be assimilated directly, and ammonia which may also be assimilated with the available carbohydrate. By the timena the  fibre-digesting bacteria have started growth  period in which they  and during the extended  attack the more resistant components of the forage,  amino acids will be scarce. It  is thus not surprising that fibre-digesting bacteria  -  22  -  have the capacity to use ammonia as a source of nitrogen. (Hungate  The formation nutritional  1952)  of ammonia in the rumen leads to two opposing  actions. First, substances such as urea, which are nutritionally  to the host, can be converted to ammonia and utilized for growth  valueless  of bacteria,  that is for the synthesis of protein, which may be subsequently digested and used by the host. By contrast, the degradation of protein to ammonia, which can be directly absorbed from the rumen, implies a source of loss of nitrogen to the host animal. The interaction  of these opposing actions is probably a  major factor leading to the relative  constancy of biological value of food  nitrogen  (crude protein)  RUMEN  PROTOZOA One effect  for  ruminants (McDonald  of acidosis in the ruminant  1952).  is the elimination  reduction in protozoa numbers as the pH drops. This is rather as the numerous species of protozoa have very different It  or severe  a complex area  nutritional  requirements.  has been suggested that below pH 5 protozoa numbers are greatly reduced  or totally  eliminated.  intermediary  (Mackenzie  1967; Thomson 1967). However, in the  period, after grain is first fed, protozoa numbers may remain constant  or even increase. Certain protozoa, notably  Entodinium caudatum. thrive  so that when grain is first fed to animals on a hay diet their  on starch  numbers increase.  Nakamura and Kanegasaki (1960) reported higher protozoa numbers in cattle fed a mixed diet of hay and grain than present were different of the difference  between  in cattle fed straight hay. Species  the hay fed and mixed diet fed cattle.  may be due to differences in protein level between rations.  The role of protozoa in ruminant  nutrition  appears to be  There seems to be some disagreement as to their role et al  Part  (1965) suggested that the major  very complex.  in metabolism. Christiansen  influence of protozoa was on volatile  -  fatty acid metabolism. However.  23  -  Klopfenstein et al  (1969) considered that  the effect: upon nitrogen metabolism was of equal if not greater than the effect  importance  of volatile fatty acid metabolism.  Christiansen et al  (1965) found that within the rumen of faunated  sheep there werevji (1)  larger amounts of volatile fatty acids produced,  (2)  altered  (3)  greater degradation of proteinaceous material as  ratios of volatile fatty acid production,  compared to defaunated sheep.  The acetate to propionate ratio was narrower  in faunated sheep than  in defaunated sheep. These authors also found that faunated better in the feedlot  than defaunated  lambs performed  lambs, but were unable to determine  which one of the three differences mentioned accounted for the improved performance. Klopfenstein et al greater dry  (1966) reported that faunation  resulted in  matter digestion.  Purser and Moir (1959) stated that the extent of pH depression and the period during which low pH prevails appear to be the major factors in determining the concentration of ciliate protozoa in the rumen when grain is fed.  RUMEN pH As mentioned  in the section on lactic acidosis, the pH of the rumen  contents drops when soluble carbohydrates are fed. Balch and Rowland (1957), showed that pH was inversely related to total volatile fatty acids present in the rumen. Briggs et al  (1957), reported that rumen pH rarely falls outside  the range of 5.0  on diets that do not lead to lactic acid accumulation.  to 7.5  -  24  -  There are numerous reports in the literature of lowered pH values induced by lactic acid accumulation. Hungate et al  (1952) noted a drop of  1.7 pH units twenty-two hours after placing soluble carbohydrate into the rumen of sheep. Briggs et al 20  (1957) reported that lactic acid levels above  mM/L were always associated with pH levels below 5.0, although values  higher than 80mM/L 4.35.  were often recorded, rumen pH levels never fell below  Brawner et al (1969) reported a drop of 3.05 pH units when cattle  were given a ration high in soluble carbohydrates. This drop in pH was associated with an increase in rumen lactic acid from 0.33 mM/L to 99.4 mM/L.  Jensen et al epithelium  (1954) reported that in animals fed barley the rumen  was necrotic and vesicated. The vesicles contained serum, erythrocytes,  leukocytes and colonies of bacteria including Scherophorus necrophorus.  These  authors considered that parakeratosis was due to the build up of acid in the rumen. They also found that the association of gastric lesions and liver abscesses showed statistical significance.  Harris (1962) also suggested a relationship between  lowered rumen pH  and liver abscesses and liver necrosis. He suggested that very acid conditions within the rumen could result in damage to the mucosa, possibly allowing release of ruminal bacteria into the bloodstream and thus to the liver.  Simon and Stovell (1969) indicated that Scherophorus necrophorus was the organism causing liver abscesses. In further examined four hundred and" thirty  work Simon and Stovell (1971)  liver abscesses and found Scherophorus  necrophorus in ninety-seven percent of the abscesses.  From the work of the above authors it would appear that high grain rations, which cause the rumen pH to drop can lead to the development  -  25  -  of parakeratosis; This parakeratosis then enables Scherophorus necrophorus to enter  the bloodstream and cause liver abscesses. Obviously anything which will  lessen the build: up of acid in the rumen will help to prevent and liver abscesses. Changing gradually  from  parakeratosis  roughage to concentrate  rations  will help to lessen the build up of acid in the rumen. This may be an important  consideration when bringing cattle or sheep into a feedlot.  PLASMA  GLUCOSE Annison et al  (1939) reported  that sheep previously housed indoors  and fed hay had increased blood glucose levels when they  were placed on  pasture. Throughout the period of grazing the blood sugar level was significantly greater  than when the animals were indo ors. The maximum  ten days after turning out to grass (approximately slightly  toward  the end of the experiment.  increased availability  level was six to  65 mg%) and then fell  These authors stated that the  of propionate may account for the rise in blood sugar,  but the supplies of lactate may be equally  or more important  as a source of  carbohydrate.  Jorgenson and Schultz (1963) reported when pelleted  roughages were fed. They also reported  fatty acids and higher propionate no difference  Roy maintained all-hay  increased blood glucose levels  by the ruminant  volatile  levels. Schmidt and Schultz (1959)  in bipod blucose levels in dairy  (1970) reported  higher total  reported  cattle fed three levels of grain.  that much higher blood glucose levels are calf fed all-concentrate  diets than by those given  diets. At sixteen weeks of age, calves on all-concentrate diets had  mean plasma glucose values of 93 jmg%  compared with 68 mg% for calves on  all hay diets. He stated that how far these high plasma glucose levels are the result of the glucogenic effect  of propionate  or to glucose-formed by  -  26  hydrolysis of starch in the intestine  -  is uncertain. Little is known of the extent  to which concentrates can escape digestion in the rumen by rapid passage into the abomasum.  Abou Akkada and el-Shazly (1964) noted higher blood blucose levels in defaunated  lambs than in faunated  lambs. Church (1969) stated that blood  glucose levels tend to rise to very high values under conditions of acidosis. It would seem logical that any ration that increase propionic acid production in the rumen could lead to increased plasma glucose levels.  -  27  -  MATERIALS AND METHODS  a:-  DRIED  GRASS FEEDING  Twenty-four  Polled Dorset lambs were: used in the feeding trial. These  lambs were weaned at eight weeks of age and assigned to three rations. The mean initial (1)  weight of the lambs was 19.2 .+  dried grass, (2)  ment, (3)  barley  0.6  50% dried grass, 50% barley  kg. The rations fed were plus a protein mineral supple-  plus a protein mineral supplement. All rations were pelleted.  Details of ration composition are given in Table 1. The lambs were given vitamins A, D and E,  v^' ' by intramuscular injection at the beginning of  the experiment and again six weeks later.  Cobalt iodized salt and water were  freely available. All animals were fed to appetite twice daily and weighed, prior to the afternoon feeding at weekly  intervals.  The dried grass used for this experiment was produced by Springbank Dehydration, Chilliwack, B.C., from Orchard grass — Ladino clover mixed stands. The forage was artificially  dired prior to fine grinding and pelleting.  Digestibility data were obtained by means of the total collection technique, using six lambs on each ration with a ten day preliminary  adjustment  period, followed by a ten day collection period. Daily fecal outputs were weighed and representative samples taken for analysis. Digestibility determined at two levels of feed intake to assess the effect  values were  of level of feeding  on nutrient digestibility. The levels used for these- determinations were 600 g and 1000  g (air-dry  weight) daily, fed to 45  feed approximately  kg male lambs. These two levels of  represented maintenance and appetite respectively.  Chemical analyses for crude protein, energy and ash were conducted according to Association of Official Agricultural Chemists procedures (AOAC  1965).  -  28  -  The acid detergent fibres (ADF), were determined by the micro Van Soest method of Waldern (1972): The data were subjected to analysis of variance and Duncan's multiple  range test.  (Steel and Torrie 1960).  At the end of the feeding period (45  kg) the animals were slaughtered  and rumen wall and rumen content samples were taken.  b:-  RATION CHANGEOVER EXPERIMENT Two trials were conducted to measure the changes occuring in rumen  lactate, rumen ammonia, rumen protozoa, rumen pH and plasma glucose when the diet of lambs was changed from  100%  roughage to 100%  concentrate.  In  the first trial the diet of four sheep was changed, over a period of seven days, from poor quality chopped hay to rolled barley. In the second trial the change was from the chopped hay to pelleted barley. Daily rumen and blood samples were taken. Four sheep (approximately and fed twice daily at 8:30 681  AM and 3:30  40kg) were individually penned  PM. The sheep were fed  g per day of poor quality chopped hay for four weeks to allow them  to adjust completely to this ration. Their ration was then changed to 454 g per day of barley. The changeover period was six days. (Table 2) and blood samples were taken at 11:30  Daily rumen  AM. A period of four weeks was  allowed to allow the sheep to adjust completely to the barley ration. Rumen and blood samples were then taken to represent adjusted values.  SAMPLING  PROCEDURES  All sampling was done at 11:30  AM, three hours after  the ;morning  feeding / Blood samples were collected in heparinized vacutainer tubes by venous puncture of the jugular vein. The samples were centrifuged at 2000 r.p.m. for  _  29  _  TABLE 1  RATION  COMPOSITION  RATION  1  (Dried grass)  Dried grass %  RATION 2 (50/50)  RATION 3 (Barley)  100  50  Barley %  —  40  80  Supplement %  -  10  20  Chemical Analysis  (DM)  CP%  22.7  18.7  16.9  ADF%  27.0  17.8  6.3  ASH%  13.8  8.9  4.0  Supplement:-  Protein-mineral  supplement containing 32% CP, 2.3%  Ca, 1.0%  P.  -  30  TABLE  CHANGEOVER  -  2  DESIGN  Day 1  681  g of hay  Day 2  567 g of hay plus 114 g of barley  Day 3  454  Day 4  340 g of hay plus 340 g of barley  Day 5  227  g of hay pi us 454  g of barley  Day 6  114 g of hay plus 454  g of barley  Day 7  454  g of hay plus 227 g of barley  g of barley  -  30  31  minutes. The plasma was then drawn  -  off with a Pasteur pipette and placed  in a test tube. The test tubes were stoppered and stored in a freezer  at --5  C.  Rumen samples were obtained by means of a stomach tube. The tube was made of hard plastic (Tygpn).  6.36  mm inside diameter.  A series of  holes were drilled at the end of the tube to prevent blocking with fibrous material.  A  plastic speculum was used to facilitate the passage of the  stomach tube through the mouth  and cdown the throat of the sheep. A  suction pump was used to draw  the samples. The rumen samples were collected  in plastic containers which were sealed as soon as the sampling was completed.  The rumen samples were strained through two  thicknesses of cheese  cloth. Ammonia concentrations were measured on the fresh samples. The remainder  of the sample was frozen for further analyses.  ANALYTICAL BLOOD PLASMA  using the enzymatic  were carried out in batches at the end of the changeover period.  The plasma was deproteinized with 5.1% hydroxide. A 0.2 10:1  zinc sulphate and 0.36N sodium  ml sample was used for the determination,  which was  with distilled water before deproteinizing. The colour development  was measured using a Spectronic 20  LACTIC  "Glucostatkit  Chemicals). Plasma was frozen after collection and glucose  determinations  diluted  -V  GLUCOSE  Glucose was determined (Worthington  PROCEDURES  at a wavelength  of 400  mjt  ACID Rumen samples were frozen after collection. Rumen lactic acid concen-  tration was determined  using the colourimetric  method  of Barker and Summerson  -  32  -  (1941) with the suggested modifications of Pennington and Sutherland (1956). The rumen content samples were deproteinized with 5.1% 0.36N sodium hydroxide. A 1.0 for the determination.  zinc sulphate and  ml sample of this diluted solution was used  In this method the lactic acid is converted into  acetaldehyde by treatment with concentrated reagent grade sulphuric acid, and the acetaldehyde determined by its colour reaction with p-hydroxydiphenyl (p-phenylphenol, Eastman Kodak Company) in the presence of cupric ions.  The colour development was read on a Spectronic 20 of 560  mji. The procedure was as follows:— A  at a wavelength  1 ml sample, after deprotein-  ization and copper-lime treatment, was added dropwise with shaking to 9 ml of ice cold concentrated reagent grade sulphuric acid. The tube was then covered with parafilm After  and placed in a boiling water bath for five minutes.  cooling, four drops of 4% copper sulphate and seven drops of the  p-hydroxyphenyl  reagent was added. The tube was then allowed to stand in  ice for one hour with occasional shaking. The tube was then placed in the boiling water bath for ninety  seconds and returned  minutes. The sample was allowed to  return  to the ice-bath for five  to room termperature  before the  colour development was read.  RUMEN pH The pH was determined after filtration.  (pH  on the fresh rumen samples immediately  meter 28 - Radiometer Copenhagen).  RUMEN AMMONIA CONCENTRATION Ammonia determinations were carried out on fresh rumen liquor immediately O'Malley  after filtering, using the microdiffusion technique of Conway &  (1942). A 2.0  ml sample of rumen liquor was used for the  determination.  -  33  -  The procedure was as follows:  By means of a small brush, a thin  coat of gum arabic fixative was applied to the outer  rim of the microdiffusion  unit.  was added to the  (Figure 2).  A 2.0  outer chamber of the added to the  ml aliquat unit and 1.0  ml of boric acid indicator-solution was  inner chamber. Approximately  were added to the outer replaced. After  whole rumen fluid  chamber of the  3 ml of magnesium oxide suspension unit and the lid was  the lid was sealed the contents of the outer  immediately  chamber were  mixed thoroughly. The unit was then placed in a cupboard for twenty-four  At the end of the twenty-four unit and 1.0  hours the lid was removed from  ml of water added to the central  hours.  the  chamber. The boric acid  indicator was then back titrated with 0.005N sulphuric acid.  PROTOZOA  COUNTS  Protozoa counts were carried out on a 15:1 The protozoa were counted, using a McMaster rumen fluid  was diluted  dilution  of rumen fluid.  Fecal Counting Chamber. The  with Sheather's sugar solution so that the protozoa  would rise to the top of the counting chamber.  Some problems were encountered when the sheep were receiving barley  as the  presence of starch granules made the counting more  difficult.  STATISTICAL ANALYSIS The results were subjected to correlation and regression analysis. The significance of the correlations were measured at the five and ten percent level, using the t-table. (Huntsberger, Two  1967).  trials were conducted. In  the diet of hay fed lambs following  Trial  1, rolled barley was introduced  the schedule in Table  into  1. In Trial 2, pelleted  barley was used. The results of the two trials were very similar and therefore were pooled for analysis and discussion.  - 34 -  FIGURE  CONWAY  2  MICRODIFFUSION  UNIT  INNER  CHAMBER  OUTER  CHAMBER  PLAN  71 mm  15 mm  Jt  31 mm  > \ L 10 mm  ft  12 mm  VERTICAL SECTION ON LINE A - B  CONWAY AND O'MALLY 1941  -  35  -  RESULTS a:-  DRIED  GRASS FEEDING  Average daily gain (ADG) approximately  20  to 40  over a fourteen week feeding period from  kg liveweight  for the three rations fed (Figure 3). treatments  did not differs significantly (P>0.05) The values were 213,  1, 2 and 3 respectively (Table  lambs was significantly (P <• 0.05) The mean daily gain was 236  3).  211  and 216  The ADG of entire  g for  male  greater than that of females on all rations.  g for males compared to  191  g for females  with no interaction between sex and ration.  The feed conversion ratio the ration  increased and was 5.37,  (FCR) decreased as the level of barley in 4.84  and 3.98  for treatments  1, 2 and  3 respectively.  The dressing percentages were 48.7,  50.5  and 53.2%  for rations 1,  2 and 3 respectively. However, gut contents were not weighed so it was not possible to compare carcass growth.  On a group basis feed intake was higher in Group 1 (dried grass) and lowest for Group 3 (pelleted  barley)  but digestible energy  intakes were  similar due to differences in DE levels of the rations. The digestible energy intakes were 3.16,  2.86  and 2.84  Meals for treatments  1, 2 and 3 respectively.  Rumen pH was higher in lambs fed dried grass. The rumen pH in those sheep was 6.74  compared with 5.78  and 5.74  for treatments  2 and  3 respectively. Digestibilities of DM, OM, gross energy, CP and ADF were measured. The DDM, DOM and DE values followed similar trends and percentage DE was significantly  (P ^ 0.05)  different  for the three treatments.  The mean DE values  -  36  -  FIGURE 3  WEIGHT CHANGE  OF LAMBS  (kg)  VS TIME (weeks)  50  -\  4d -J  IO -A  0  1  2  3  4  5 Weeks  6  7  8  9  10  11  12  -  37  TABLE 3  ANIMAL  PERFORMANCE RATION 1  DATA RATION 2  RATION 3  Average daily gain (ADG) All animals g  213  211  216  Males g  237  239  233  Females g  189  183  200  Food conversion ratio (FCR)  5.37  4.84  3.98  Dressing percentage  48.7  50.5  53.2  Rumen pH  6.74  5.78  5.74  Feed intake: DM/day kg  1.04  0.95  0.76  DE/day Meals  3.16  2.86  2.84  -  were 66.1,  69.1  and 82.0%  38  -  for rations 1, 2 and 3 respectively. Digestibility  of CP declined as the level of barley decreased, the means being 67.4, 70.0  and 79.0%  for treatments  1, 2 and 3 respectively. Differences between  the means were significantly different  (P<0.05). Digestibility values for ADF  indicated that this was highest for the dried grass and lowest for the pelleted barley. The means were 50.0,  45.8  and 24.2%  for groups 1, 2  and 3 respectively. The digestibility data are summarized in Table 4. The effect  of level of feed intake on the digestibility of the energy  of the feed was studied. With the dried grass ration the increase in intake from 600  to 1000  g resulted in a significant (P>0.05) decrease in digestibility.  The digestibility of energy also tended to be lower at the higher levels of intake for the other two  rations but the differences were not significant  (R>0.05). The mean values at an intake 82.2%  and at  1000  g, 64.4,  68.3  of 600 g were 67.7, 69.8 and  and 81.7%  for treatments  1, 2 and 3  respectively.  There was no significant (P>0.05) effect  of level of feed intake on  protein digestibility, but there was a tendency for digestibility  of protein to  be lower at the higher level of intake for the dried grass and 50-50 rations. The mean protein digestibilities at an intake of 600 g were 68.4, 78.9%  and at  1000  g, 66.5, 68.7  and 79.2% for treatments  71.2 and  1, 2 and 3  respectively. The appearance of the rumen contents were quite different three rations. (Appendix 3)  for the  The rumen contents from the sheep on pelleted  barley were watery with the solid portion having a "porridge" like appearance. The contents of the rumen of the sheep on dehydrated grass contained large amounts of trapped gas and had a frothy  appearance. They were dark green  colour and had an odor very similar to that of the feces of cattle on lush grass. The rumen contents of the sheep on the 50-50 ration were very similar to those on the dehydrated grass, however, there was less trapped gas and the contents were ithicken.'^t .thlcksr.  -  39  -  TABLE 4  DIGESTIBILITY  DATA  RATION  1  (%)  RATION 2  RATION 3  Gross energy  66.1a  69.1b  82.0c  DM  63.1,  70.6  82.3  OM  66.2  72.31.  83.2  CP  67.4a  70.0b  79.0c  ADF  50.0a  45.8b  24.2c  Values on the same line followed by different letters are significantly different. (P<0.05)  -  40  -  RUMEN WALL CHARACTERISTICS On the barley ration the papillae were short, clumped and appeared keratinized. On the 50-50 ration the papillae were clumped, dark  in colour,  closely packed and short. On the dehydrated grass ration, the papillae were extremely  variable, some were long and flakey, with others very  undeveloped. (Appendix 4)  b:-  RATION  LACTIC  CHANGEOVER EXPERIMENT  ACID The tabulated data are presented in Appendix 5.  Rumen lactate  levels increased over the period of the trail (Figure  The increase in lactic acid concentration from day 1 (100% (100%  barley)  was 321.2  hay)  4).  to day 8  mg %. The most marked increase occured between  day 7 and day 8.  The rumen lactate concentration was positively correlated (P 4. 0.10) the level of barley hay (P <• 0.10)  with  in the ration and negatively correlated with the level of  (Table 5).  Rumen lactate and rumen pH were negatively corre-  lated (P < 0.10). There was a negative correlation (P < 0.05)  between lactic  acid levels and protozoa numbers.  As stated above, lactic acid levels rose markedly during the changeover period. The correlation between (P < 0.10)  rumen lactate levels and rumen pH was significant  suggesting3 that the "build-up" of lactic acid was responsible for  the drop in rumen pH. The symptoms of indigestion (.'scouring, refusal of feed, drooping of the head), also appeared to be related to the increases in rumen lactate.  In all sheep the onset of symptoms of "indigestion" corresponded to  the build-up of rumen lactate.  -  41  -  TABLE 5  *  Significance at 5% level.  **  Significance at 10% level.  BARLEY HAY FED FED  BARLEY  HAY  FED  FED  RUMEN  pH  -0.64**  0.72**  RUMEN  LACTATE  0.29**  -0.36**  R U M E N PROTOZOA NUMBERS  _Q 8 0  0  .20*  RUMEN pH  RUMEN LACTATE  RUMEN RUMEN PROTOZOA AMMONIA NUMBERS  PLASMA GLUCOSE  -0.64**  0.29**  -0.08  -0.37**  0.34**  0.72**  -0.36**  0.20*  0.43**  -0.38**  -0.70**  0.37**  0.38**  -0.23**  -0.23*  -0.06  0.14  0.37** -0.23="  C..r,-•  0.44**  -0.70**  RUMEN  A M M O N I A -0.37**  0.43**  0.38** -0.06  0.44**  PLASMA  G L U C O S E 0.34**  -0.38**  -0.23**  -0.17  Correlations between  0.14  ration fed, rumen * pH, rumen lactate,  rumen ammonia, and plasma glucose when the ration roughage to concentrate  over an eight day period.  -0.17  rumen protozoa numbers,  of lambs is changed from  -  43  -  RUMEN AMMONIA CONCENTRATION Tabulated  results are presented in Appendix 6.  Rumen ammonia levels increased initially day  1 values. The highest level (6.0  mg%)  and then dropped below  occured on day 3 (Figure  The rumen ammonia concentration was negatively with barley  intake and positively correlated  levels were positively correlated  RUMEN  (P^O.10)  (P < 0.10)  correlated  5).  (P <  0.10)  with hay intake. Ammonia  with protozoa numbers (Table  5).  PROTOZOA NUMBERS Tabulated  results are presented in Appendix 7.  Rumen protozoa numbers increased during the changeover period to day 7 and then declined sharply (Figure in numbers over the adjustment  6).  There was a further  period.  Protozoa numbers were positively correlated Protozoa numbers and pH were positively correlated  (P < 0.05) (P^ 0.10).  protozoa numbers and the rumen lactate levels were negatively (Table  reduction  with  hay.intake.  Rumen correlated  (P < 0.05).  5).  Protozoa numbers increased when barley was added to the ration. This initial increase was followed  by a decline in numbers as the level of barley  increased. The sharpest decline in numbers occured on day 8, which corresponded with the largest increase in lactic acid.  FIGURE 5 RUMEN AMMONIA CONCENTRATION (mg%) VS TIME (days)  ( Study 2)  mg% 12.0 11.0 10.0 9.0 8.0 7.0 6.0 -| 5.0 4.0 3.0 2.0 1.0 3  4  6  7  1  Standard Deviation  8  35 DAYS  FIGURE 6 13.0 12.0  RUMEN PROTOZOA NUMBERS PER ml OF RUMEN FLUID (X 10 ) 6  VS TIME (days)  -I  (Study  2)  11.0 10.0 9.0 8.0 7.0 6.0 . 5.0 4.0  -I  3.0 2.0 1.0 J i  i  1  1  1  1  '  1  2  3  4  5  6  7 Standard Deviation  r—  8  DAYS  -  46  -  RUMEN pH Tabulated results are presented in Appendix 8.  The rumen pH dropped during the changeover period and continued a slight decline over the adjustment  Rumen pH was negatively positively correlated  (P <• 0.10)  period (Figure  correlated  7).  (P ^ 0.10)  with hay intake.  with barley  intake and  Rumen ammonia and rumen  protozoa numbers were positively correlated with rumen pH (P < 0.10). Blood glucose and rumen lactate were negatively (Table 5)  The relationship between  correlated with rumen pH (P  rumen pH and rumen lactate  0.10).  is demonstrated  in Figure 8.  The molar concentration of lactic acid reached in this study was 76.3  mM/L.  BLOOD GLUCOSE CONCENTRATION The tabulated  results are presented in Appendix 9.  Plasma glucose increased during the changeover period. There was a slight drop in plasma gluco se:j levels during the adjustment :  were still above initial  values. (Figure 9)  Blood glucose levels were positively correlated intake and negatively  period but levels  correlated  rumen pH were negatively  (P ^ 0.10)  correlated  (P <• 0.10)  with hay intake.  (P < 0.10). (Table  5)  with barley  Blood glucose and  -  48  -  RUMEN LACTATE CONCENTRATION VS RUMEN pH (Study 2)  FIGURE 8  r  1  2  3  4  5  6  DAYS  7  8  35  8.0  FIGURE 9  PLASMA GLUCOSE (mg%) VS TIME (days)  Study 2)  mgyo  Standard Deviation  DAYS  35  -  50  -  DISCUSSION AND CONCLUSIONS  The dressing percentage figures obtained in the first trial agree with those of Lonsdale et al  (1971) who found that dressing percentage increased  when barley was added to grass wafers for cattle. Although weight gains for the trial were similar for the three rations, the dressing percentage was 4.5  percentage units higher for lambs fed straight barley compared to straight  grass. The difference between straight grass and 50-50 grass-barley was  1.8  percentage units in favour of the 50-50 ration. Therefore, although the three rations appear to give equal liveweight gains, the carcass gain would probably be higher for the barley fed animals. Unfortunately  no sample lambs were  slaughtered at the start of the trial so that the actual differences in carcass gain between rations could not be measured. Using the dressing percentages obtained it would appear that a 50  kg lamb would yield 24.3,  25.3  and 26.6  kg carcass respectively for rations 1, 2 and 3. This represents an approximate difference of 9.2%  in carcass yield between  rations 1 and 3.  Coleou (1973) reported difficulties in obtaining the degree of finish wanted All  on calves fed straight grass. This was not observed in this experiment.  lambs were adequately finished at approximately 45 kg.  The replacement value of dried grass for barley 1.35:1. This compares favourably with the by Connell (1973) in work  in this experiment was  1.25:1 replacement ratio reported  with dairy cattle .  The digestible energy percentage of treatment 2 was not as high as would have been expected from the values for dried grass and barley separately. A  similar effect when dried grass and barley were combined has been reported  by Tayler and Lonsdale (1970). These workers have concluded that with un-  -  51  processed dried grass the digestibility  -  of a mixed diet of grass and barley  was greater than that of grass alone at low digestibilities but the difference between diets declines with increasing digestibility  of the grass. When the grass  has an organic matter digestibility exceeding 75% the addition of barley tends to depress the digestibility Wainman et al  of the mixture below that of grass alone. Similarly,  (1970) reported metabolizable energy to remain almost constant  with rations ranging from all dried grass to all barley, but they found net energy almost doubled over this range. The digestibility of OM of the grass used by Wainman et al  (1970) was slightly in excess of 70%.  In the present experiment digestibility  of OM was 66.2%  for the dried  grass. Tayler and Lonsdale (1970) have proposed the following equation to predict digestibility  of mixed diet when the value for the dried grass is known: Y  =  39.0  +  0.48  X  Y  =  the OM digestibility  of the mixed diet.  X  =  the OM digestibility  of the dried grass.  where:  The OM digestibility  of the mixed ration in this experiment was 72.3%  compared to a value of 70.8%  predicted by the equation of Tayler and  Lonsdale (1970);' This would appear to be a reasonable approximation considering that the equation was derived with unprocessed dried grass while the material used in this study was ground and pelleted. The value which would have been predicted from the digestibilities of grass and barley was 75%.  Tayler and Lonsdale (1970), Kromann (1973), Londale et al (1971) have suggested this associative effect  may be due to a reduction in fibre  digestion. In this - study ADF digestibility data did not indicate that the digestibility  of this fraction was less in the mixed ration than that which would  -  52  -  have been prediced from the values for the components. It other associative effect  Blaxter  accounts for the reduced  would appear some  digestibility.  (1962) has suggested that the decline in digestibility  with  increased level of feed intake may be due to the increased rate of passage and a decrease in fibre  digestion. While depressions in digestibility  at  the  higher levels of feed intake were observed in this study, it was not possible from the results to  identify  reduced fibre digestion as the cause. The use of  only 3 animals per treatment for the digestibility tributed  determinations  may have con-  to the lack of significant differences. Rate of passage was not measured  in this study and therefore  Very  its effect  is not known.  little can be concluded on the effect  rumen papillae. Comparing papillae development  of these rations on  becomes difficult  because the  location of the rumen wall samples was not noted. Therefore some differences may be due to differences  in location of sample. The papillae appeared to be  developed more in sheep fed straight dehydrated  No health experiment  grass than  in the other groups.  problems were encountered with the lambs during this  and the results suggest that dried grass could be used successfully  in the intensive rearing of early  weaned  lambs. The decision would be primarily  dependent on the relative costs of dried grass and protein supplemented cereal grain rations.  In the second trial the introduction receiving hay led  of (barley into the ration  of sheep  to changes in the blood and rumen fluid, the most notable  of these being the "build-up" of lactic acid in the rumen. This one factor appears to be the dominant  result as it  in turn affects several other  This "build-up" of the lactic acid leads to lowered which increase initially  due to the availability  parameters.  pH levels. Protozoa numbers  of starch are then inhibited by  -  the lowered pH.  53  -  The introduction of soluble carbohydrates, in the form of  grain, into the ration of ruminants, normally results in a drop in rumen pH. The depression of 1.64 the value;- of 1.70  pH units observed in this study was very similar to  pH units reported by Hungate et al  (1952).  The drop in rumen pH corresponded closely with the increase in lactic acid concentration in the rumen. This agrees with the work et al (1969) and Briggs et al  of Brawner  (1957). The molar concentration-* of lactic acid  reached in this study is very similar to that reported by Briggs et al  (1957).  Saliva contamination was difficult to avoid when obtaining rumen samples. This may have increased the pH of the rumen fluid. However, the initial  pH values correspond to those reported by Gilchrist and Clark (1957),  Thomson (1967), Ahrens (1967) and Brawner (1969).  Rumen ammonia increased somewhat when barley was first fed. This was due in part to increased nitrogen intake which was not utilized. As the rumen microbes adapt they are able to utilize the increased levels of available carbohydrate as an energy source for microbial synthesis. Therefore, rumen ammonia levels drop after the initial and agrees with the work  rise. This trend was evident in this trial  of Annison (1959) and Mclntyre (1970).  Rumen pH and the rumen ammonia appear to be related (P< 0.10). This agrees with the work  of Reis and Reid (1959), who suggested the effect  of pH is probably an effect  on the enzymes concerned in the deamination of  amino acids.  Plasma glucose increased as the level of grain in the ration increased. This increase was probably due to one of two factors, the availability  of lactate  as a carbohydrate source in the rumen or to glucose formed by hydrolysis of  54  _starch in the intestine. As Roy  -  (1970) stated, little is known of the extent to  which concentrates can escape digestion in the rumen by rapid passage into the abomassum. When the animal is adjusted to a grain diet, the higher glucose values are probably due to the increased propionate production. However, during the changeover period propionate production is impeded and therefore it is not likely it is the source of increased glucose levels.  Protozoa numbers increased when barley was added to the ration. This initial increase was followed by a decline in numbers as the level of barley increased. These data agree with the work of Mackenzie (1967), Thomson (1967) and Nakamara and Kanagesaki (1969). The initial increase in protozoa numbers may be due to the increased availability of starch causing an increase in numbers of the protozoa capable of using starch. As the pH declines protozoa numbers drop.  The correlation between protozoa numbers and rumen ammonia levels was positive. There is some disagreement as to which is the governing variable. Purser and Moir (1966) stated protozoa numbers reflect, rather than cause, variations in the accumulation levels of ammonia. However, Klopfenstein et al (1966) stated that protein degradation in the rumen was greater in the presence of protozoa, resulting in elevated rumen ammonia concentrations. Warner (1956) and Christiansen et al (1965) tend to support this latter view. The data from this study does not aid in this controversy.  Rumen and blood fatty acid levels would have aided in interpretation of results. Blood lactate levels should also have been measured. 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Skidmore. 73-80. WAINMAN, F.W., BLAXTER, K.L., and SMITH, J.S. 1972. The utilization of the energy of artificially dried grass prepared in differed ways. Journal of Agricultural Science. 78: 441-447. WAINMAN, F.W., BLAXTER, K.L. and SMITH, J.S., and DEWEY, P.J.S. 1970. Calorimetric studies of the nutritive value of dried grass. Proceedings of the 5th Symposium on Energy Metabolism of Farm Animals. Lucerne, Switzerland. WALDERN, D.E. 1973. Dehydrated grass in dairy cattle rations in British Columbia. Proceedings of the First International Green Crop Drying Congress. University of Oxford, Oxford, England. Edited by C.L. Skidmore. 168-175. WALKER, D.J. 1968. The position of lactic acid and its derivatives in the nutrition and metabolism of ruminants. Nutrition Abstracts and Reviews. 38: 1-11.  -  64  -  WALLEN1US, R.W., HIBBS, J.W. and CONRAD, H.R. 1966. Effect of feeding different proportions of beet pulp, corn silage, or alfalfa hay on digestibility of dehydrated alfalfa pellets. Journal of Dairy Science. 49: 1266-1269. WARNER, A.C.I. 1956. Proteolysis by rumen microorganisms. Journal of General Microbiology. 14: 733-748. WILKINS, R.J., LONSDALE, C.R., TETLOW, R.M. and FORREST, T.J. 1972. The voluntary intake and digestibility by cattle and sheep of dried grass wafers containing particles of different sizes. Animal Production. 14: 177-188. WILKINS, R.J. 1973. The effects of processing on the nutritive value of dehydrated forages. Proceedings of the First International Green Crop Drying Congress. University of Oxford, Oxford, England. Edited by C.L. Skidmore. 119-134.  -  65  -  APPENDIX  DEBINIMON' OF  1  MODULUS OF  FINENESS  :— Percentage of a 250 gram sample of ground feed remaining on each of seven screens. (3/8, 4, 8, 14, 28, 48, and 100 mesh) and in the pan following a 5 minute test.  egSCREEN  MESH  PERCENT OF MATERIAL ON EACH SCREEN  3/8  1.0  X 7 =  7.0  4  2.5  X 6 =  15.0  8  7.0  X 5 =  35.0  14  24.0  X 4 =  96.0  28  35.5  X 3  48  22.5  X 2 =  45.0  100  7.5  X 1 =  7.5  PAN  0.0  X 0  0.0  TWAIS  100.0  THEREFORE  MODULUS OF 312/100 =  AMERICAN  - 106.5  312.0  FINENESSES  3.12  SOCIETY OF AGRICULTURAL ENGINEERS YEARBOOK, 1970.  APPENDIX 2 DEFINITIONS  1.  wafers  —  made by compressing chopped forage in a piston-type press.  2.  cobs  —  made by compressing chopped forage in a roller-die press.  3.  pellets  —  made by compressing ground forage mill) in a roller-die press.  (hammer  -  67  -  APPENDIX 3  PHOTOGRAPH  OF  RUMEN  CONTENTS  -  68  -  APPENDIX PHOTOGRAPHS  OF  RUMEN  4 WALL SAMPLES  -  69  -  APPENDIX 4 (continued)  RATION 1  RATION 1  100% GRASS  -  70  -  APPENDIX 4 (continued)  RATION 2  70-A  APPENDIX 4 (continued)  APPENDIX RUMEN  DAY  LACTIC ACID  5  CONCENTRATIONS  LACTIC ACID mg%  1  31.7  2  31.8  3  23.1  4  39.7  5  47.1  6  59.6  7  65.2  8  352.9  35  127.6  CONCENTRATIONS ARE THE AVERAGE  OF  EIGHT  SHIE'EP  -  72  -  APPENDIX  RUMEN  DAY  AMMONIA  6  CONCENTRATIONS  RUMEN  AMMONIA  1  4.2  2  4.9  3  6.0  4  4.5  5  3.2  6  3.3  7  3.3  8  2.6  35  2.0  CONCENTRATIONS  ARE THE AVERAGE  OF  EIGHT  mg%  SHEEP  -  73-  -  APPENDIX 7 RUMEN  DAY  PROTOZOA NUMBERS  PROTOZOA NUMBERS/ ml  1  3.2  2  3.0  3  3.4  4  2.9  5  4.4  6  3.6  7  4.1  8  2.0  35  0.8  CONCENTRATIONS ARE THE AVERAGE OF  EIGHT SHEEP  X10  6  -  74  -  APPENDIX  8  K10MEN pH  DAY  pH  1  7.44  2  7.14  3  6.99  4  6.98  5  6.80  6  6.71  7  6.75  8  6.01  35  5.80  CONCENTRATIONS  ARE THE  AVERAGE OF  EIGHT SHEEP  -  75  :  -  APPENDIX 9  PLASMA  DAY  GLUCOSE  CONCENTRATIONS  GLUCOSE mg%  1  37.3  2  42.8  3  41.5  4  41.1  5  42.2  6  53.1  7  49.7  8  52.4  35  43.5  CONCENTRATIONS ARE THE AVERAGE  OF  EIGHT  SHEEP  

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