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Sulphate salts affect water consumption : drinking behaviour and welfare of beef cattle Zimmerman, Amanda Shilo 2003

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Sulphate Salts Affect Water Consumption, Drinking Behaviour and Welfare of Beef Cattle by Amanda Shilo Zimmerman B.Sc.Agric, University of British Columbia, 2001 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE In THE FACULTY OF GRADUATE STUDIES (Faculty of Agricultural Sciences) We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA August 2003 © Amanda Zimmerman, 2003 In presenting this thesis in partial fulfillment 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. Faculty of Agricultural Sciences Department of Animal Science The University of British Columbia Vancouver, Canada Abstract Sulphate (SO4) salts are present in many rangeland water sources and can negatively affect animal welfare and production. Existing guidelines for SO4 in cattle drinking water are based on Na2S04 although many water sources contain higher MgSCM concentrations. This research examined the role that MgSCM plays in water consumption, drinking behaviour and health of beef cattle. In a series of three experiments, yearling beef cattle were given water containing a range of SO4 levels (1 - 4806 ppm) as Na2S04, MgS04 or K2SO4. In Experiment 1, water consumption by eight heifers given either tapwater or water containing Na2S04, MgS04 or K2SO4 at a target concentration of 3000 ppm SO4 was monitored in a 4x4 Latin Square with 7-d treatment periods. Experiment 2 used eight yearling heifers, watered with tapwater or water containing Na2S04 or MgS04 at target concentrations of 1500, 3000 or 4500 ppm SO4, in 2-d treatment periods separated by 2 d tapwater access. In Experiment 3, 16 yearling heifers and steers were given tapwater or water containing Na2S04 at a target concentration of 2000 ppm S0 4 , or MgS04 at target concentrations of 2000 and 4000 ppm SO4 in 21-d treatment periods separated by 7 d tapwater access. Both [\la2SO4 and MgS04 showed a dose effect with a stronger negative response for MgS04 than Na2S04 (P < 0.01). Average daily water consumption did not vary (P > 0.05) between tapwater and SO4 salts at either 2000 or 3000 ppm S0 4 , but declined significantly at and above 4000 ppm S0 4 (P < 0.01). Variability in consumption between drinking events increased as MgS04 content rose, as did the number of refusals to drink (P < 0.05). Percent fecal DM, tested after 7, 11 and 21 d on treatment, increased following 21 d of MgS0 4 consumption at approximately 4000 ppm S 0 4 (P < 0.05), but no effect was seen at lower SO4 concentrations (for any salt) or over shorter durations (7 and 11 d). These findings indicate that cattle find MgS04 aversive and at sufficiently high concentrations or length of exposure, water consumption, drinking behaviour and physiological status are disrupted. ii Table of Contents Abstract L ii Table of Contents. . iii List of Tables v List of Figures vi List of Appendices vii List of Abbreviations viii Acknowledgements ix Chapter I: General Introduction Importance of Water to Cattle 1 Factors Affecting Water Consumption 2 Water Quality and Sulphates 5 Providing Water to Cattle on Rangeland 12 Study Objectives 13 References 16 Chapter II: The Effect of Sulphate Salts on Water Consumption by Beef Cattle Introduction 27 Methods and Materials 28 Experiment 1 . .28 Experiment 2 30 Results 32 Experiment 1 32 Experiment 2 33 Discussion : 34 References 39 Chapter III: Magnesium Sulphate Affects Water Consumption and Drinking Behaviour of Beef Cattle Introduction 44 Methods and Materials ; 45 Results 48 Discussion..... 53 References 56 Chapter IV: Conclusions 60 References 64 Appendices Appendix I.. 67 iv List of Tables Table 2-1 Daily water consumption (mean, SD, minimum and maximum) and fecal dry matter values for Exp. 1 :. 3 3 v List of Figures Figure 2-1 Mean (± SEM) daily water consumption (L) for Exp. 2. Values are the means of the mean daily water consumption of the eight animals calculated separately for each 2-d treatment period 34 Figure 3-1 Mean ± SEM of the four measures based on 12 animals in each of the four treatments: (1) average daily water consumption, (2) standard deviation of water consumption of each animal over 42 drinking events, (3) number of drinking events (maximum = 42) when the animal refused to drink, and (4) fecal DM at d 21. Horizontal bars show the three specific comparisons tested by pair-wise comparisons with n = 8 animals per pair. * P <0.05, ** P < 0 . 0 1 50 Figure 3-2 Examples of the variation in water consumption over the 42 drinking events (2 per day). A: When given tapwater, animal #118 consumed water at every drinking event, usually between 15 and 30L. B: When given 2012 ppm SO4 as MgS04, animal #104 failed to drink in seven events and consumed < 15 L in six others. C: When given 4060 ppm SO4 as MgS04, animal #121 drank < 15 L in 10 events and refused to drink in another 23 52 vi List of Appendices Appendix I Summary of mineral content in ponds and dugouts in the Kamloops region. 67 vii List of Abbreviations DM Dry matter DMI Dry matter intake K2SO4 Potassium sulphate M g S 0 4 Magnesium sulphate N a 2 S 0 4 Sodium sulphate PEM Polioencephalomalacia RH Relative humidity S 0 4 Sulphate TDS Total dissolved solids TSS Total soluble salts Acknowledgements This research was carried out through the generous financial support of the Beef Cattle Industry Development Fund, British Columbia Cattlemen's Association, Vancouver Foundation, Agriculture and Agri-Food Canada's Matching Investment Initiative Program and the UBC Animal Welfare Program. I would like to gratefully acknowledge the guidance and support of my committee members, Drs. David Fraser, Doug Veira, Dan Weary and Marina von Keyserlingk. Their endless patience and thoughtful insight over the duration of my thesis preparation was invaluable and I couldn't have reached this final stage without them. A special thank-you belongs to Dr. Veira, who welcomed me to Kamloops and repeatedly went above and beyond the call of supervisory duty. I would also like to acknowledge the late Dr. Jim Shelford, who was an outstanding undergraduate supervisor and provided me with the support to continue into graduate school. The staff at the AAFC Kamloops Range Research Unit were helpful without exception. Glen Garland deserves special mention for patiently providing me with an excellent example of how to handle cattle, and always knowing how to do things better than I, as do Larry Maio and Tim Wallace for helping me out every time something broke, which was often. The assistance of Barb Wheatley, Sue Garvey and Justin Kopp with the execution of experiments, lab work and data entry is greatly appreciated. A huge thank-you belongs to Lavona Liggins, who helped with almost every aspect of my experimental design and execution and helped me to keep everything in perspective. My fellow students in the UBC Animal Welfare program provided me with endless support and friendship. In particular, thank-you to Cassandra Tucker for generously allowing me to use her as a sounding board for statistics and other issues, Sara Dubois for her insight on thesis preparation, and Nicole Fenwick for being a terrific officemate. I would like to thank my parents, who have supported me not only during my thesis work, but in the 22 preceding years in so many ways that it would take another thesis just to list them all. Kimberley and Kyle are the kind of siblings that make me want to set a good example as their big sister. Joan and Alan Grout helped me in more ways than they can imagine. Finally, I would like dedicate this thesis to Ray Grout, who traveled this path with me with good humor and unwavering support, drove a total of 24704 km during my thesis research, and now acknowledges that cows truly are magnificent creatures. ix CHAPTER I - General Introduction Importance of Water to Cattle Water has many properties that make it an ideal fluid for the support of life. It has a high specific heat and conductivity (Frandson and Spurgeon, 1992) and readily acts as a lubricant and solvent (Fraser et al., 1993). It forms the largest component of an animal's body and is required for all biological functions including biochemical reactions, ion and mineral transport, dilution of cell contents, thermoregulation, digestion and metabolism of nutrients, disposal of waste materials and fetal development (Pond et al., 1995). The importance of water in the maintenance of life becomes clear when one considers that while a food-starved animal can recover after losing half of its body protein, almost all its fat reserves, and 40% of its body weight, a water-deprived animal will die if over 10% of the body's water reserves are lost (French, 1956). Fitzsimons (1979) recognized that thirst, the subjective sensation resulting from a lack of water, follows only severe pain and hunger for air in the hierarchy of physiological drives, highlighting the significance of water for homeostatic functioning and animal welfare. When access to water is limited or restricted, there are consequences for animal production, health and welfare. Barrio et al. (1991) found that when water was withheld from sheep for four hours, feed intake declined. In studies where cattle had their water access restricted to 60% of their ad libitum consumption values, feed intake also dropped (Balch et al., 1953). Others have found that mild water restriction, such as a 25% reduction from ad libitum consumption, reduces intestinal volume of water but does not affect feed intake (Butcher et al., 1959). Cattle probably tend to drink in excess of their requirements; hence, moderate restriction of water consumption likely reduces excess ingestion before reaching a level of restriction where the animal's requirements for water are not met. 1 Animal health and welfare may also be compromised by a lack of water. For example, animals fed diets high in salt develop salt toxicity unless they have plentiful water to flush the excess salt through their digestive system (Riggs et al. 1953). In cases of extreme dehydration, the concentration of water in body tissues is decreased, leading to concentration of blood and less efficient circulation and transportation of oxygen (Sykes, 1955). Brain lesions (Padovan, 1980) and hypernatremia, the clinical manifestation of exceptionally high serum Na concentrations, have also been noted in cases of severe dehydration (Knowles, 1956). Other physiological effects of reduced water consumption have been noted. One is depression of thermoregulation, which is particularly pertinent for cattle grazing in hot climates (Ittner et al., 1951). Water deprivation has been shown to influence digestion through changes in rumen contraction (Christopherson and Kennedy, 1983), rumination activity (Gordon, 1965) and rate of passage (Musimba et al., 1987), resulting in decreased dry matter intake (DMI) (Utley et al., 1970; Little et al., 1978). Metabolic parameters, such as urea-N and serum Na, glucose and osmolality, may also be affected by water restriction (Little et al., 1976; Cole and Hutcheson, 1981). Factors Affecting Water Consumption Cattle require a large volume of water to maintain homeostasis. Literature values suggest that growing beef cattle drink 26.5 - 65.9 L per day (Winchester and Morris, 1956; NRC, 1996). This wide range is the result of water requirements varying considerably, depending on a variety of animal-based and environmental factors. Leitch and Thomson (1944) noted the difficulties in comparing water consumption across trials, as the entirety of conditions that affect water consumption are not commonly reported. Animal-based factors such as slow metabolic rate will decrease water consumption (Langhans et al., 1995), while phenotypic characteristics such as breed (Ragsdale et al., 2 1951) and body size (Winchester and Morris, 1956) play various roles in water requirements. Gender is known to influence DMI (Hicks et al., 1990a) and as DMI and water consumption are closely related, it can be said that gender indirectly affects water consumption. Rumen osmolality has also been suggested as a factor influencing water requirements and hence consumption (Dewhurst et al., 1998). It is well established in the literature that increases in DMI (Winchester and Morris, 1956; Castle and Thomas, 1975; and Little and Shaw, 1978) and dry matter (DM) content of feed (Thomas, 1971; Stockdale and King, 1983; Dewhurst et al., 1998) are associated with increased water consumption. Water consumption is also positively correlated with milk production (Thomas, 1971; Little and Shaw, 1978; Dewhurst et al., 1998) and insufficient consumption will result in lowered milk production (NRC, 1988). This latter effect could be particularly problematic for lactating cows and their calves in areas where access to good-quality water is restricted. Ambient temperature (Stockdale and King, 1983; Rouda et al., 1994) and relative humidity (RH) (Ali et al., 1994) influence the requirements for and hence consumption of water. However, ambient temperatures must be relatively high to influence water consumption; under conditions of low temperature (2.4 - 13.3 °C) there appears to be little effect (Castle and Thomas, 1975). Hicks et al. (1990a) suggested that cattle experience heat stress at ambient temperatures above 25° C and indeed, under "hot" conditions (i.e., greater than 30 °C) water consumption increases as temperatures rise (Rouda et al., 1994; Molina and Tuera, 2000). It appears that there is a range of ambient temperatures in which cattle can maintain homeostatic conditions without increasing their water consumption, and at temperatures above this range the animals must compensate through higher water consumption. From the literature, 25-30 °C emerges as an upper threshold above which 3 ambient temperature plays an increasingly significant role in the regulation of water consumption. Beyond ambient temperature and RH, climatic factors such as rainfall, hours of sunshine and wind speed affect water consumption. Stockdale and King (1983) found that daily water consumption was positively correlated with hours per day of sunshine and evaporation. Day length may also influence water consumption as cattle rarely drink between sunset and sunrise (Sneva, 1970). Diet composition also affects water consumption. For example, diets high in fibre lead to increased loss of water in fecal matter, raising demands for water consumption. High dietary intake of salt, protein and minerals such as Na and K result in increased urine excretion and hence boost the demand for water (Riggs et al., 1953; Butcher et al., 1959; ARC, 1980). The observed effects of increased intake of these substances can primarily be attributed to greater renal filtration (Weeth and Lesperance, 1965) needed to remove excess ions from the body; the greater volume of urine that results from this increased filtration requires animals to increase their water consumption to replace the volume lost in urine. Riggs et al. (1953) observed that cattle fed a high-salt diet excreted approximately seven times more urine than those on a low-salt diet. This trend is also evident in other ruminants; Barrio et al. (1991) noted that water consumption by sheep was stimulated by infusion of salt into the rumen. Trough design features such as physical dimensions (Pinheiro Machado, 2003) and refill rate (Thomas, 1971; Andersson, 1984) will also affect water consumption. It has been suggested that 10% of a herd must be able to drink concurrently (ARC, 1980); therefore, troughs must be able to accommodate several animals at once and refill at a rate sufficient to supply a continuous flow of water to the drinking animals. Certainly competition and 4 social interactions around water troughs have the potential to influence water consumption by individuals. Individual animals differ considerably in water consumption (Little and Shaw, 1978; Sekine et al., 1989; Dahlborn et al. 1998). Although some of this variation can be accounted for by daily variation in the above-mentioned factors, particularly DMI and milk yield (Little and Shaw, 1978), other undefined factors also play a role, suggesting that there is still ample room for refinement of water consumption prediction methods. Finally, water quality is a key factor affecting water consumption. If water contains compounds that diminish palatability, cattle will reduce their water consumption (Embry et al., 1959; Weeth and Hunter, 1971; Patterson et al., 2002) or seek alternative water sources (Digesti and Weeth, 1976). Alternatively, through conditioned feed aversions, cattle may learn to limit their consumption of water containing compounds that result in gastrointestinal discomfort (Garcia and Hankins, 1975; Provenza, 1995; Ralphs and Provenza, 1999). Water Quality and Sulphates Water quality is an inclusive term often used to describe the biological, chemical and physical properties of water with respect to their influence on the suitability of water for an intended purpose, such as drinking (Price 1985). Biological pollutants, including algae, manure and urine, lower the quality of drinking water, as do chemical pollutants such as minerals and the products of industrial development (Veenhuizen and Shurson, 1992; Carson, 2000). It is perhaps a disadvantage that water is a very effective solvent (Price 1985), as many of the biological and chemical pollutants easily become dissolved in the water that cattle are then required to drink. Water quality can also be impaired by the physical properties of the water, including temperature, colour and turbidity (McKee and Wolf 1963, Price 1985). Temperature, for example, has the potential to alter the sensation 5 of substances dissolved in water (Goatcher and Church 1970a, Zoeteman 1980) and has been shown to affect water consumption by cattle (Ittner et al, 1951; Lofgreen et al., 1975). Water quality as assessed by cattle involves a number of sensory inputs. Taste appears to be of primary significance in determining the acceptability of a water source (Bruvold and Gaffey, 1969; Goatcher and Church, 1970), but sight, smell and touch also play roles (Zoeteman, 1980). Sound can also be used in sensory assessment as the sound of running water can give an indication of viscosity and degree of aeration (Zoeteman, 1980). The various properties of water that elicit a response from cattle can together be considered as affecting the palatability of the water. Provenza (1995) proposed that conditioned feed aversions, based on post-ingestive feedback, can also affect the palatability of water. When ingestion of a substance is followed by gastrointestinal discomfort, cattle can learn to avoid the substance in subsequent tests (Matthews and Kilgour, 1980; Provenza and Balph, 1988). Therefore, palatability may not be dictated solely by taste, smell or other direct sensory factors. Because sulphate (SO4) is a predominant mineral contaminant in many water sources, there is a large volume of literature on this compound. It is a global issue for animal production, as evidenced by research in Canada (Boila, 1988; McLeese et al., 1991; Smart, 2000), the United States (Embry et al., 1959; Digesti and Weeth, 1976), South Africa (Steyn and Reinach, 1939), Australia (Saul and Flinn, 1978; Robertson et al., 1996; Harper et al., 1997) and the Middle East (Bahman et al., 1993; Solomon et al., 1995). Many species of animals appear to be affected by the SO4 content of water, including humans (Backer, 2000), dogs (Roth and Crittenden, 1934), poultry (Gordon and Sizer, 1955), swine (Paterson et al., 1979; Veenhuizen et al., 1992; Anderson et al., 1994), sheep (Peirce, 1960; Johnson et al., 1968) and cattle (Embry et al., 1959; Hansard and Mohammed, 6 1969; Weeth and Hunter, 1971; Robertson et al., 1996). This review will focus on the effect of SO4 on cattle, while drawing from the relevant literature on other species. Early work in this area actually focused on water salinity (Heller, 1933). However, with the recognition that SO4 was, in many areas, the predominant compound responsible for high salinity (Embry et al., 1959), emphasis changed to incorporate or concentrate on SO4. Among the various SO4 salts, sodium sulphate (Na2SCM) and magnesium sulphate (MgSCU) are the most common (Carson, 2000) and have been studied most extensively; of the two, [\la2SO4 is most prominent in the research literature. A wide range of responses to SO4 in drinking water have been reported. Embry et al. (1959) described toxic effects in heifers drinking water containing 6760 ppm SO4 as Na2S04. The symptoms described by these authors are very similar to the clinical presentation of polioencephalomalacia (PEM), a neurological disorder commonly associated with high intake of sulphur. At lower SO4 concentrations of 2700 and 4732 ppm, no effect on feed intake or weight gain was observed; in fact, water consumption increased slightly and free choice consumption of trace minerals salts declined over control animals (Embry et al., 1959). In this early research, however, there was little true replication, and the conclusions need to be evaluated cautiously. In the next major addition to SO4 literature, an American group looked at the effect of Na2S04 in drinking water on beef cattle growth and performance. In one experiment, they determined that SO4 concentrations of 3493 ppm reduced water consumption by 35% and feed intake by 30%, with an associated loss of weight; this level of SO4 was deemed unsuitable for growing animals (Weeth and Hunter, 1971). Weeth and Capps (1972) observed lower weight gains in Hereford heifers supplied with water containing 1462 and 2814 ppm SO4 as Na2S04; although water consumption was unaffected by these treatments, feed intake did drop by 12.4% when the animals were given the higher of the 7 two SO4 concentrations. In yet another experiment, water consumption, feed intake and weight gain were unaffected by 1250 and 2500 ppm SO4 as Na2S04 (Digesti and Weeth, 1976). This last set of results is supported by the work of Robertson et al. (1996), who did not observe an effect of 2000 ppm SO4 on the water and feed intake or weight gain of Brahman steers. More recent work by Harper et al. (1997) demonstrated that at concentrations of less than 2000 ppm SO4, and with gradual increases in concentrations to this level, there appeared to be little effect of S 0 4 on water or feed consumption. However, at SO4 concentrations above 2000 ppm, negative effects on water and feed intake were observed, notably reductions of 40% in water consumption and 30% in DMI at 4000 ppm SO4 (Harper et al., 1997). In contrast, Loneragan et al. (2001) found effects at lower SO4 levels; in their research, as SO4 concentration in drinking water increased from 136 to 2360 ppm, water consumption, average daily gain and feed efficiency decreased. An effect of S 0 4 has also been presented in studies where SO4 was considered as part of the total soluble salts (TSS) (Saul and Flinn, 1985) or total dissolved solids (TDS) (Patterson et al., 2002) in drinking water. Saul and Flinn (1985) observed reductions in feed intake and weight gains at TSS concentrations above 5000 ppm and attributed part of this effect to the 650 ppm S 0 4 present in the overall salt mixture. Water consumption, DMI, average daily gain and feed efficiency all declined in cattle offered water of 3000 and 4000 ppm SO4 included in TDS concentrations of 4800 ppm and 6200 ppm, respectively (Patterson etal. , 2002). Cattle will avoid drinking water containing S 0 4 at certain concentrations if given a choice. In a tapwater vs. S04-contaminated water preference test, Weeth and Capps (1972) found that with water at and above 1450 ppm SO4, its intake accounted for less than 29% of the animals' total daily water consumption, and for less than 20% at 2150 ppm. A similar 8 trend was seen in a second preference experiment where less than 35% of the total daily water consumption by heifers was of water containing 2018 ppm SO4 and less than 20% at 3317 ppm SO4 (Digesti and Weeth, 1976). Although the animals were not given a choice between water sources in the experiment by Weeth and Hunter (1971), they refused to drink water containing 5070 ppm SO4 for 24 hours, indicating a significant aversion. The above differences in results may be due to a number of factors that vary from one experiment to another. These include breed, age, physiological status, nutritional plane and prior experience of the animals, diet, climate, method of SO4 introduction (abrupt or gradual), time on treatment and method of presenting the options (preference test or no choice). Each factor may influence the animals' response to SO4, making it difficult to compare across experiments. Despite these difficulties, the general trend in the literature suggests that certain concentrations of SO4 are acceptable. Summarizing from literature, it appears that water and feed intake begin to be reduced by SO4 at concentrations around 2500 - 3000 ppm. Above 3500 ppm SO4, feed and water consumption, weight gain, health and physiological effects of high-S04 water are observed. Aside from effects on variables such as water and feed consumption, weight gain, feedrgain ratio (feed efficiency) and drinking behaviour, there are a host of physiological changes associated with high levels of SO4 in drinking water. Weeth and Hunter (1971) measured substantial increases in methemoglobin and serum S04-combined with diuresis in heifers drinking water containing 3493 ppm S 0 4 as Na2S0 4 . Smart et al. (1986) noted a positive effect on copper status when SO4 was removed from cattle drinking water. The percentage of free water lost in urine was significantly greater for animals drinking water containing 3 4 9 3 ppm SO4 as Na2S04 than those drinking tapwater (Weeth and Hunter, 1971). Scouring (diarrhea) was also observed in cattle drinking water containing 6760 ppm SO4 (Embry et al., 1959). In general, subclinical physiological changes will occur before the 9 physical symptoms or behavioural changes; hence, the absence of gross histological symptoms in some studies may not indicate a true lack of SO4 effect. Olkowski (1997) has suggested that "subclinical toxicity from excessive S intake and associated with secondary nutritional deficiencies may represent a plethora of non-specific metabolic disorders" that may not be diagnosed, or if diagnosed, may not be attributed to SO4. Production variables may also be affected by SO4 in drinking water. Loneragan et al. (2001) found that slaughter weight and hot carcass weight decreased, and dressing percentage and predicted yield grade tended to decrease, as SO4 concentration in drinking water for steers on a feedlot diet increased to a maximum of 2360 ppm. Over-consumption of SO4 can result in unanticipated effects such as nutritional imbalances and metabolic disorders. Sulphur has been shown to depress apparent and true selenium digestibility (Ivancic and Weiss, 2001). At concentrations greater than 500 ppm, SO4 may also exacerbate deficiencies of copper, zinc, iron and manganese (CCREM, 1987). Zinn et al. (1997) have suggested that more than 0.2% S in the diet will reduce the net energy value of that diet. Numerous studies have also implicated SO4 in the etiology of PEM (Hibbs, 1983; Gooneratne et al., 1989; Hamlen et al., 1993). The etiology of PEM and the role that S plays in this disorder have been disputed. Some authors contend that the conversion of SO4 and S to hydrogen sulphide (H2S) in the rumen, and its subsequent eructation and absorption through the lungs, is responsible for toxicosis leading to PEM (Bird, 1972; Loneragan et al., 1997; McAllister et al., 1997). Others have hypothesized that thiamine status, on which elevated levels of S may have a detrimental effect, is involved in the development of PEM (Olkowski et al., 1991; Olkowski et al., 1993), or that thiamine plays a role in the prevention of the clinical histology associated with PEM (Olkowski et al., 1992). What is clear is that when cattle are exposed to water containing high concentrations of SO4, the incidence of PEM is increased (Harries, 1987; 10 Beke and Hironaka, 1991; Niles et al., 2000). PEM-like histology, such as neurological lesions, has also been observed in yearling cattle deprived of water for over 48 hours (Padovan, 1980), although these lesions were attributed to hypernatremia (Knowles, 1956) and as such cannot be appropriately classified as PEM. The maximum acceptable concentration of SO4 in cattle drinking water is influenced by the total amount of SO4 or S that the animals will ingest in a day. For example, under hot conditions, water consumption dramatically rises (Winchester and Morris, 1956). If the available water is rich in SO4, then the greater consumption of water will lead to high SO4 intake, and could lead to animals ingesting inappropriately high levels of S. For example, an animal drinking 30 L of water per day, with a SO4 concentration of 2000 ppm, will consume 0.06 kg of SO4. If that same animal increases its water consumption to 40 L per day, it will ingest 0.08 kg of SO4; this 0.02 kg increase may have negative physiological effects. Several studies (Raisbeck, 1982; Sadler et al., 1983; Beke and Hironaka, 1991) have noted that total level of S in the diet, from both feed and water sources, is more closely correlated with incidences of PEM than SO4 levels in water alone. The effects of SO4 salts on water consumption and drinking behaviour are likely mediated through several mechanisms. Sulphate is a known laxative (Fraser, 1991; Gomez et al., 1995) and salts are diuretic (Weeth and Lesperance, 1965). These effects could result in increased demand for water to replace that lost through extra fecal moisture and urine, or have gastrointestinal consequences that produce conditioned feed aversions (Provenza, 1995). Sensory effects may also play a role. Salts with heavy molecular weights, such as Na2S04 and MgS04, are known to have a bitter taste in humans (Montcrieff, 1967). Goatcher and Church (1970a; 1970b) tested taste responses of ruminants and found cattle to discriminate against bitter tastes and strong salt concentrations. Preference testing 11 suggests that an animal's initial reaction to water containing SO4 may be a response to the sensory properties of that compound (Weeth and Capps, 1972; Digesti and Weeth, 1976). Providing Water to Cattle on Rangeland Cattle obtain water from several sources. They fulfill most of their requirements by drinking water; this volume is supplemented by the water consumed in feed and formed within the animal as the result of metabolic oxidation processes (ARC, 1980). Historically, the term 'water consumption' has been used to describe voluntarily consumed water, with 'water intake' referring to water derived from consumption as well as from feed and via metabolic processes (Winchester and Morris, 1956). The percentage of total water intake that comes from feed depends on its water content; lush forage may contain approximately 70% water, while dried or cured forages such as hay may have less than 10% moisture (Pond etal. , 1995). In British Columbia, as in many parts of the world (e.g. United States, Australia), beef cattle are commonly grazed on rangeland for at least part of the year. The rangelands used for this purpose in BC include semi-arid grasslands (Bawtree et al., 1998). For cattle grazing on these grasslands, drinking water comes from three sources: groundwater such as wells, standing water such as lakes, ponds and dugouts, and flowing water such as streams and rivers. There are a variety of issues surrounding the use of surface water bodies (standing and flowing water) by cattle. Cattle often congregate in riparian zones. Aside from the benefit of a ready water supply, riparian zones often provide lush, nutritious vegetation, shade, shelter (Hennan, 1998) and favourable topography (France and Haywood-Farmer, 1998). McLean et al. (1963) noted that the nutritive quality of several sedges found in riparian areas is superior to that of forage found in upland areas. However, by spending large amounts of time in riparian zones, cattle may overgraze fragile vegetation, leading to bank destabilization, loss 12 of small mammal and fish habitat, and long-term environmental damage (Kauffman and Kreuger, 1984; Sheffield et al., 1997). Cattle may wade into and defecate in water, leading to contamination of that water source (Miner et al., 1992; Larsen, 1998) and increased risk of disease transmission between animals. Miner et al. (1992) noted that fecal coliforms and fecal streptococci are common in water sources where livestock have drunk. Escherichia coli and Salmonella have also been found in cattle drinking troughs; hence water may be a source of exposure to these pathogens (Price, 1985; LeJeune et al., 2001), as well as to Tubercle, Brucellae, Listeria, Leptospira and Coccidia (McKee and Wolf, 1963). Furthermore, if cattle defecate into water used as a human drinking water source, there is potential for contamination of drinking water and pathogen transmission. To address the problems of cattle drinking from riparian areas, the beef industry has promoted alternative watering developments such as troughs. Water can be pumped to troughs from any water source, including on-site storage if water has to be brought into an area. It has been shown that installing an off-stream water trough significantly decreases cattle use of adjacent stream riparian areas (Clawson, 1993; Veira and Liggins, 2002). Given the concerns over cattle drinking water from riparian areas, increased use of troughs by ranchers is anticipated. In conjunction with troughs, ranchers may also fence all or part of the riparian zones to prevent cattle from drinking from these sources (France and Haywood-Farmer, 1996). As either of these options involves limiting access to water, we need to determine which water bodies should be used for rangeland cattle, either as a source of water to be pumped into troughs, or as unfenced water bodies to allow cattle direct access. In order to do this, an understanding of water quality and how it affects water consumption by cattle is required. 13 Study Objectives This study addressed water quality as both an animal welfare and beef production issue. As consumer interest in animal welfare issues grows, beef producers will be under greater pressure to adhere to codes of practice and demonstrate that their animals are raised in a humane manner. With provision of water playing a key role in cattle health and welfare, any advancement in this area of production should be welcomed by consumers. Additionally, improved access to water resulting in enhanced production, through higher average daily gains and lower incidence of metabolic disturbance, would provide beef producers with financial incentive to make the changes necessary to provide adequate water to their cattle. Finally, as producers themselves become more aware of the issue of water quality (Pratt, 2002), it will be important to provide them with information that they can use to improve their production practices. The research conducted for this thesis aimed to clarify the role of various SO4 salts on water consumption and drinking behaviour by cattle. Existing literature has not explored whether two common SO4 salts, Na2S04 and MgS04, have different effects on the level of SO4 that cattle will tolerate; it was intended that this research serve to clarify this issue and refine existing guidelines on acceptable levels of SO4 in cattle drinking water. The first study was designed to examine the effect of different SO4 salts on water consumption and fecal DM, with cattle provided with tapwater or water containing either potassium sulphate (K2SO4), N a 2 S 0 4 or MgS04 at target SO4 concentrations of 3000 ppm for 7-d treatment periods in a 4><4 Latin Square design. A second experiment provided cattle with tapwater or water containing Na2S04 or MgS04 at target SO4 concentrations of 1500, 3000 and 4500 ppm, in 2-d treatment periods separated by 2-d periods of tapwater access, to compare the effects of these two cations on water consumption at increasing SO4 concentrations. Based on the results of the first two trials, a third study focused on the effect of MgS04 on water 14 consumption, drinking behaviour and fecal DM. In this experiment, cattle were given tapwater, Na2S04-water at a target SO4 concentration of 2000 ppm, or MgS04-water at target SO4 concentrations of 2000 and 4000 ppm in 21-d treatment periods separated by 7 d of tapwater access. For all experiments, treatments were applied on a within-animal basis. In this thesis, Chapters II and III are written as independent papers for publication, and therefore briefly repeat some of the background in the introduction and discussion sections. 15 References AN, S., L.A. Goonewardene, and J.A. 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Morris. 1956. Water intake rates of cattle. J. Anim. Sci. 15:722-740. 26 Zinn, R.A., E. Alvarez, M. Mendez, M. Montafio, E. Ramirez, and Y. Sehen. 1997. Influence of dietary sulfur level on growth performance and digestive function in feedlot cattle. J. Anim. Sci. 75:1723-1728. Zoeteman, B.C.J. 1980. Sensory Assessment of Water Quality. Pergamon Series on Environmental Science Volume 2. Pergamon Press, Exeter. 27 Chapter II - The Effect of Sulphate Salts on Water Consumption by Beef Cattle Introduction Cattle grazing on rangeland often drink from surface waters that are contaminated with SO4 salts. Studies show that water consumption by cattle begins to decrease at SO4 levels of around 2500-3000 ppm (Weeth and Hunter, 1971; Harper et al., 1997) and declines further at higher concentrations (Embry et al., 1959). High-S04 water has also resulted in reduced feed consumption, lowered weight gains (Embry et al., 1959; Weeth and Hunter, 1971), scours (Embry et al., 1959), diuresis (Weeth and Hunter, 1971) and sub-optimal production (Loneragan et al. 2001). High levels of dietary S, which can be supplied through water containing SO4, have been implicated in reducing the net energy value of a diet (Zinn et al., 1997), interference with mineral status (Smart et al., 1986; Ivancic and Weiss, 2001), and the development of PEM (Olkowski 1997). Guidelines for maximum acceptable limits of SO4 in cattle drinking water (CCREM 1987) are generally based on the Na2S04 literature. However, many water sources contain high levels of Mg and K as well as Na, and in these cases response to the water may be influenced by the cations as well as by SO4. Herbivores have a recognized appetite for Na (Denton, 1982), and readily consume dissolved Na salts while avoiding comparable concentrations of Mg and K salts (Fraser and Reardon, 1980). Sodium is closely linked to thirst mechanisms while Mg and K play no such role (Fitzsimons, 1979). Hence, there are good reasons to expect that animals will respond differently to different cations, and that water quality guidelines should incorporate the effects of the cation. The objective of this work was to clarify the role of different cations in acceptability of S04-contaminated water for cattle. 28 Methods and Materials The two experiments took place at Agriculture and Agri-Food Canada's Range Research Unit, in Kamloops, British Columbia. Average maximum, minimum and mean daily temperatures during the experiments, which ran almost concurrently, were 28.3°C, 13.5°C, and 20.5°C, and average maximum and minimum RH were 72% and 31%, respectively. There was 0.6 mm precipitation during the experimental period, falling as 0.4 and 0.2 mm on two separate days. Experiment 1 Animals & Management. Eight barren yearling Angus heifers (initial weight: 372 ± 10 kg, mean ± SD) were studied between July 3 1 and August 27, 2001. All animals had been raised in the same controlled environment; five had no known previous access to water contaminated with sulfate compounds while the other three had been used in a preliminary trial involving exposure to water containing 3000 ppm SO4 as Na2S04. Each animal wore a neck collar carrying a transponder for a particular Calan headgate (American Calan Inc., Northwood, U.S.A.) which allowed them to access only one water container. Animals were housed together in a pen that contained a combination of concrete and dirt flooring. Two covered areas were separated by a dirt-floored alleyway; the communal feedbunk was located near one of the shelters and the water containers by the other. The feedbunk and drinking areas were lit by red 85W lights. Animals were fed orchardgrass hay {Dactylis glomerata) (mean 12.0% CP DM basis, 96.2% DM) a d libitum, refreshed twice daily between 0 7 0 0 to 0 8 0 0 and 1400 to 1500. The hay contained 0.03% Na, 2.31% K, 0.20% Mg, and 0.24% S on a DM basis. All animals could eat from the feedbunk at the same time. Animals had ad libitum access to a cobalt iodized stock salt block composed of a minimum of 99.0% NaCI (Windsor; The Canadian 29 Salt Company Limited) and to a mineral mix containing 2.0% Mg and 25.0% NaCI (Trail Blazer 1:1 Range Mineral for Beef Cattle with Selenium; New-Life Feeds, Lethbridge AB). Water was supplied to individual animals in 55 L transparent plastic containers through the Calan headgates in two daily "drinking events", one at 1000 to 1100 and one at 1700 to 1830. In each drinking event cattle were allowed to drink until all animals had stopped drinking and left the area of the water containers. Once this happened, headgates were locked to prevent further access to water. Water containers were then weighed to the nearest 50 g and refilled to between 30 and 50 kg with the appropriate water treatment. Change in weight was defined as water consumption for that drinking event. Containers were emptied daily, scrubbed and refilled. Experimental Design & Data Collection. At the start of the experiment, two animals were allocated to each of four treatments: tapwater, Na2S04, MgS04, or K2SO4 at a target concentration of 3000 ppm S 0 4 . Treatment solutions were prepared with ACS grade (> 99 . 0 % purity) anhydrous Na2S0 4 , MgS04 heptahydrate or K2SO4, which were added to tapwater by weight to make up the target SO4 concentration. Actual SO4 concentrations averaged 1 ppm for tapwater and 2794, 2839 and 2897 ppm SO4 for Na2S04, MgS04 and K 2 S 0 4 treatments, respectively, based on the sampling methods described below. After the animals had been on their respective treatments for 7 d, the groups switched treatments; this was repeated every 7 d for four weeks until all animals had been exposed to every treatment. Initial treatment allocation was random; treatments were then applied in sequential order according to a Latin Square design. Group feed consumption was determined by weighing hay before each feeding and weighing back refusals the following morning. Fecal samples were taken by rectal grab sampling once weekly on the morning after d 7 of each treatment period, before starting the 30 next treatment. Samples were then weighed, dried at 60°C for 48 h and then re-weighed, with % moisture calculated from the difference between the two weights. Hay samples were taken at each feeding (twice daily) and pooled weekly. Hay samples were analyzed for CP by micro-Kjeldahl, for Mg, K and Na content by atomic absorption spectrophotometry and for S using nitric-perchloric acid digests by ICP emission spectrometry. Dry matter was determined by drying samples at 60°C for 48 h. Water samples (50 ml) were taken at each drinking event from each water bucket and pooled according to treatment across all eight animals and treatment days. The water samples were analyzed for SO4 by the turbidimetric method (AOAC, 1990) and for Ca, Mg, K and Na content by atomic absorption spectrophotometry. Animals were visually monitored daily for changes in their health status for signs of excessive weight loss and symptoms of PEM such as "star-gazing", head pressing and loss of coordination (Hamlen et al., 1993; Niles et al., 2000). Data Analysis. Graphical examination suggested no difference in response to treatment between the three animals with and the five without previous exposure to water containing SO4; therefore data for all eight animals were pooled for the final analysis. For each 7-d treatment period, only the last 4 d were used in the analysis to allow animals to adjust to treatment. Because water intake of individual animals can vary significantly from day to day (Little and Shaw, 1978), a single mean value for daily water consumption, averaged over the 4 d period, was used for each animal. Effect of treatment on mean daily water consumption, and on fecal DM content, were tested using the general linear model procedure of SAS (SAS Inst. Inc., Cary, NC). Experiment 2 Animals & Management. Eight barren yearling Angus heifers (initial weight 345 ± 8 kg) were studied from August 2 to 29, 2001. All animals had been raised in the same 31 controlled environment with no known previous access to water contaminated with SCM compounds. Animals were housed in two groups of four in pens with a combination of dirt and concrete flooring (in front of the feedbunk). Each pen had a covered shelter sufficiently large for all animals to use it at the same time. Animals were fed as in Exp. 1 except that in this experiment the orchardgrass hay was 96.2% DM and contained 12.6% CP, 0.24% S, 0.03% Na, 2.40% K and 0.20% Mg on a DM basis. Water was provided twice daily, at 1030 to 1200 and 1530 to 1815, in 80 L plastic containers placed in the feedbunk. During these times animals were locked in the back of the pen and then released one at a time to drink from a single container. Containers were emptied every other day, scrubbed and refilled. Treatment solutions were made using the appropriate SO4 salt as described for Exp. 1. Experimental Design & Data Collection. Seven treatments were used: a tapwater control, and six SCvwater treatments comprising Na2S04 or MgS04, each offered at target S 0 4 concentrations of 1500, 3000 or 4500 ppm. Actual SO4 concentrations were 1, 1559, 3194, 4806, 1610, 3306 and 4662 for tapwater and target S 0 4 concentrations of 1500, 3000 and 4 5 0 0 ppm as Na2S04 and MgS04, respectively. Seven animals were allocated to the seven treatments randomly without replacement for the first test period and then proceeded through the remaining treatments in a set order. Hence there was one animal on each treatment in each period, except that the eighth animal had the same sequence as one of the others. Animals remained on a treatment for 2 d (a total of four drinking events) followed by 2 d on tapwater to minimize carryover effects between treatments and to ensure that the animals remained well hydrated. Water consumption at each drinking event was calculated by subtracting final from initial volumes based on 2-L intervals marked on the side of each container. 32 Feed consumption and animal health data were collected as described for Exp. 1. Feed and water samples were collected as in Exp. 1; hay samples were pooled in 4-d periods and water samples were pooled for each 2-d treatment period across all 8 animals, yielding one sample per treatment. Data Analysis. Water consumption per day was determined by taking mean daily values over the 2-d treatment period, thus yielding a single value per animal on each treatment. Graphical examination in Microsoft Excel (Microsoft Corporation, Redmond, WA) suggested a trend for water consumption per drinking event to decline as the concentration of SO4 in the water increased, for both Na2S04 and MgS04. Further analysis used a mixed model (SAS Inst. Inc., Cary, NC) to model covariance structures for these data; the "unstructured" covariance structure was determined to be the most suitable model for these data. This analysis tested whether the effect of SO4 dose varied between the two salts and tested the effect of dose for each salt. Paired t-tests were then used to compare the means of average daily water consumption for Na2S04 and MgSCM at the target SO4 concentrations of 3000 and 4500 ppm SO4. Results Experiment 1 Daily water consumption varied widely between individuals (Table 2-1). One animal consistently had the greatest mean daily water consumption on all treatments, but the animal with the lowest mean daily water consumption varied with treatment. There were no differences (P = 0.70) in mean daily water consumption between the treatments. There was a trend (P = 0.06) towards greater fecal DM content when the animals were given water containing any of the SO4 salts (Table 2-1). 33 Table 2-1. Daily water consumption (mean, SD, minimum and maximum) and fecal dry matter for heifers in Exp. 1 Daily Water Consumption, L Fecal DM, % Treatment [SCM], ppm Mean8 SD Min Max Mean6 SEM Tapwater 1 39 6 31 45 12.8 0.3 Na2S04 2794 37 8 26 52 13.9 0.7 MgSC-4 2839 37 4 30 43 13.4 0.7 K2SO4 2897 38 6 32 51 13.9 0.5 3 Values are the means of the mean daily water consumption for the eight animals, calculated separately for each treatment, based on 4 d of data per treatment b Values are the mean fecal DM for the eight animals, calculated separately for each treatment Group DMI measures revealed that the eight heifers ate on average 8 kg/animal/d (ranging from 6 to 11 kg/animal/d). No instances of compromised animal health were recorded. Experiment 2 Mixed model analysis revealed a dose response for both MgS04 and Na2S04, with decreasing water consumption as SO4 concentration increased (Figure 2-1). The negative slope of intake vs. concentration was steeper for MgSC-4 than for Na2S04 (P < 0.01). The difference between the two cations was particularly evident at the highest SO4 concentration where average daily consumption for MgS04 (13 ± 4 L/d) was much lower (P < 0.01 by paired t-test) than for Na2S04 (30 ± 6 L/d). There was a wide range in response of cattle to water containing the higher SO4 concentrations. Several animals drastically reduced their water consumption at high SO4 concentrations, while others responded with only modest decreases in consumption. For example, when given water at 4 5 0 0 ppm SO4 as MgS04, one heifer drank 4 L/d and another drank 32 L/d. Average daily water consumption at 3000 ppm SO4 was not significantly different (P = 0.16) between Na2S04 and MgS04. 34 Tapwater Na 2 S0 4 MgS0 4 45 0 1500 3000 4500 1500 3000 4500 Target S 0 4 Concentration, ppm Figure 2-1. Mean (± SEM) daily water consumption (L) for Exp. 2. Values are the means of the mean daily water consumption of the eight animals calculated separately for each 2-d treatment period. Average DMI, monitored for the group, was equivalent to between 5 and 12 (mean 9) kg/animal/d. No instances of compromised animal health were observed. Discussion The strongest evidence for different effects of Mg and Na on water consumption by cattle comes from the different dose responses seen in Exp. 2. In that experiment, MgS04 and Na2S04 did not result in different intakes at 1500 or 3000 ppm SO4, but the differences were highly significant at 4500 ppm. Exp. 1 did not detect differences between the three cations, but this may be because the SO4 concentration (3000 ppm) was too low for the effect to be detected. The decline in water consumption with rising SO4 levels seen here is consistent with existing literature (Harper et al., 1997; Loneragan et al., 2001). Other research has also found that SO4 affects water consumption at and above 3000 ppm 35 (Embry et al., 1959, Weeth and Hunter, 1971; Harper et al., 1997), but differential response to the cation (Na or Mg) appears not the have been reported. The differences in Na2S04 and MgSCU acceptability seen in this work, particularly at higher concentrations, are not surprising given the distinct functions of these ions in the body. Specifically, Na is the principal extracellular cation (Fitzsimons, 1979) and plays a very important role in homeostasis through the co-transport of glucose and amino acids and is involved in active transport through the Na + /K + pump, while Mg plays a critical role in the derivation of energy from ATP (Frandson and Spurgeon, 1992). As salt composition can affect palatability in humans (Bruvold and Gaffey, 1969), it is possible that cattle may have also responded to differences in this property between the two salts. Further, differences in post-ingestive consequences (CCREM, 1987) may also play a role in the acceptability of the two cations. For example, while both Mg and SO4 are known purgatives (Harvey and Read, 1973), the effect of Na is less clear. Roth and Crittenden (1934) observed that while either Na2S04 or MgSC-4 increased the intestinal water content of dogs, MgS04 appeared to have a more substantial effect. Addison (1968) noted the importance of considering the Mg salt component of water quality because scouring, loss of condition or death can occur in animals drinking water with high Mg concentrations (500 ppm Mg as part of 15000 ppm total salts). High levels of Mg have also been implicated in central nervous system impairment (Fraser et al., 1991). The unique physiological system that causes a specific appetite for Na could also affect the acceptability of this cation (Denton, 1982). In some circumstances, Na appetite might override aversions to high levels of SO4, whereas the lack of Mg-specific appetite could lead to a different response to MgS04. In the present study, because cattle had ample access to Na, no Na appetite would be expected, but there may still be a tolerance or positive response to Na that does not occur with Mg. Further, Na is linked to thirst 36 mechanisms through complex regulatory systems (Fitzsimons, 1979; Blair-West et al., 1989), a n d animals need to make up both lost water and Na when they become dehydrated (Rolls and Rolls, 1982). Interactions of this nature may cause different responses to the cations in drinking water, particularly over longer exposure periods where dehydration resulting from reduced SCvwater consumption may become a factor. For all salts, there was wide variation between animals in response to SO4 presumably resulting from differences in individual aversion thresholds to SO4 in water. Aversion thresholds can be defined as the concentration at which animals demonstrate that they find a compound to be unpalatable by altering their behaviour, either by reducing water consumption or discriminating against it in a preference test (Digesti and Weeth, 1976). Such phenomena have been described elsewhere as taste discrimination (Bell and Williams, 1959), taste quality (Bruvold and Gaffey, 1969), behavioural taste thresholds (Goatcher and Church, 1970a;b), and discrimination and rejection thresholds (Weeth and Capps, 1972). Aversion thresholds are known to vary in humans (Zoeteman, 1980) and similar differences may well occur in cattle. Goatcher and Church (1970a) demonstrated a trend in variability of aversion thresholds in ruminants offered water containing acetic acid, where response varied by as much as 71% between two groups of sheep. In a trial preliminary to this work, variation in the aversion threshold of SO4 was clearly demonstrated when one heifer refused to drink water containing 3 0 0 0 ppm SO4 as N a 2 S 0 4 , while four others readily drank the same water. The aversion threshold for S 0 4 -contaminated water can be influenced by species, age, gender, physiological status, diet composition (McKee and Wolf, 1963; Goatcher and Church, 1970b) and season or climate (Ray, 1987). The influence of these factors can largely be ruled out in these experiments as the animals were uniform in these characteristics. Previous experience with the compounds in question can also play a role in 37 taste response (Provenza and Balph, 1987) but in these experiments preliminary analysis suggested that response to SO4 was similar for animals with and without previous exposure. Bell and Willams (1959) used monozygotic twin calves to demonstrate that aversion thresholds may be genetically controlled. Associations of taste with negative post-ingestive consequences may also be genetically fixed (Fischer, 1967) and thus could result in varying aversion thresholds between different genetic lines of cattle; this factor was not controlled for in this experiment although all the animals were of the same breed. Additionally, Goatcher and Church (1970a) suggested that normal biological variation in aversion thresholds could allow grazing animals to make the most efficient use of a variety of vegetation. Individual variability in aversion thresholds could account for the lack of treatment differences at lower SO4 concentrations in both Exp. 1 and 2. Once the SO4 concentration increased to approximately 4500 ppm, the water became sufficiently unpalatable to elicit a more consistent rejection of the water. Treatment differences may also have been obscured because the ingestion of saline water (i.e. water containing a surplus of ions) increases the demand for water (Silanikove, 1997) and its intake could result in a continuous feedback loop whereby animals remain thirsty while they are drinking the saline water. This thirst could override much of the tendency to decrease consumption of water containing compounds associated with low palatability or conditioned feed aversions. Variation in response to S04-water may also have been influenced by the physical array of the pens and water containers. Although the cattle drank from individual containers in Exp. 1, they could see the behavioural responses of their pen mates. Behaviours shown by some cattle, such as increased tasting of S04-contaminated water and longer time spent at the water container per drinking event, may affect the response of other animals through social facilitation (Clayton, 1978; Ralphs and Provenza, 1999). Alternatively, Calan gates are 38 known to interfere with social interactions (Phipps et al., 1983; Sowell et al., 1999) which could have also affected the reaction to SO4 and water consumption by individual animals in Exp. 1. At rangeland watering sites, where cattle can drink as a group, it is possible that social factors would reduce individual variation. According to the NRC (1996), cattle similar to those used in this research require approximately 4 1 L water daily, depending on animal and environmental factors. This is in close agreement with average daily water consumption values for all treatments in Exp. 1 and for tapwater in Exp. 2. At approximately 4500 ppm SO4, average daily water consumption dropped well below this level for Na2S04 (30 L/d) and especially for M g S 0 4 (13 L/d). Large stores of rumen water (Hecker et al., 1964) and the ability to withstand several days of water deprivation without long-term consequences (Weeth et al., 1967) may have allowed the cattle to maintain low water consumption for the short duration of these experiments. Presumably, the animals would be unable to sustain such low consumption over longer time periods without becoming dehydrated, or would be forced to reduce their feed intake to compensate for decreased water consumption (Bond et al., 1976). Alternatively, longer treatment periods could force the cattle to increase their consumption of poor quality water (Weeth and Capps, 1972). Dehydration, reduced feed intake and long-term consumption of high-S04 water all have negative consequences for animal welfare and production; hence, the further investigation of Na2SC»4 and MgSCU in cattle drinking water is warranted. 39 References Addison, J.M. 1968. Harmful levels of magnesium salts are not uncommon. J. Agric. 66:468-469. AOAC. 1990. Method 973.57: Sulfate in water - turbidimetric method. Pages 330-331 in Official Methods of Analysis. 15th ed. Assoc. Offic. Anal. Chem., Arlington, VA. Bell, F.R. and H.L Williams. 1959. Threshold values for taste in monozygotic twin calves. Nature (Lond.). 4657:345-346. Blair-West, J.R., D.A. Denton, M.J. McKinley, and R.S. Weisinger. 1989. Sodium appetite and thirst in cattle subjected to dehydration. Am. J. Physiol. 257:R1212-1218. Bond, J., T.S. Rumsey, and B.T. Weinland. 1976. Effect of deprivation and reintroduction of feed and water on the feed and water intake behavior of beef cattle. J. Anim. Sci. 43:873-878. Bruvold, W.H. and W.R. Gaffey. 1969. Evaluative ratings of mineral taste in water. Percept. Motor Skill. 28:179-192. CCREM. 1987. Canadian Water Quality Guidelines. Canadian Task Force on Water Quality: Agricultural Uses - Livestock Watering. Canadian Council of Resource and Environment Ministers, Ottawa, ON. Clayton, D.A. 1978. Socially facilitated behavior. Q. Rev. Biol. 53:373-392. Denton, D. 1982. The Hunger for Salt. Springer-Verlag, New York, NY. Digesti, R.D. and H.J. Weeth. 1976. A defensible maximum for inorganic sulfate in drinking water for cattle. J. Anim. Sci. 42:1498-1502. Embry, LB. , M.A, Hoelscher, R.C. Wahlstrom, C.W. Carlson, L M . Krista, W.R. Brosz, G.F. Gastler, and O.E. Olson. 1959. Salinity and livestock water quality. S. Dakota Agr. Exp. Sta. Bull. 481. Brookings, SD. 40 Fischer, R. 1967. Genetics and gustatory chemoreception in man and other primates. Pages 61-81 in The Chemical Senses and Nutrition. M.R. Kare and 0. Mailer, eds. The Johns Hopkins Press, Baltimore, MD. Fitzsimons, J.T. 1979. The Physiology of Thirst and Sodium Appetite. Cambridge University Press, Cambridge, England. Frandson, R.D. and T .L Spurgeon. 1992. Anatomy and Physiology of Farm Animals. 5 t h ed. Lippincott Williams & Wilkins, Media, PA. Fraser, C M . , J.A. Bergeron, A. Mays, and S.E. Aiello, eds. 1991. 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Saline purgatives act by releasing cholecystokinin. Lancet. 2(1):185-187. Hecker, J.F., O.E. Budtz-Olsen, and M. Ostwald. 1964. The rumen as a water store in sheep. Aust. J. Agric. Res. 15:961-968. Ivancic, J. Jr. and W.P. Weiss. 2001. Effect of dietary sulfur and selenium concentrations on the selenium balance of lactating Holstein cows. J. Dairy Sci. 84:225-232. Little, W. and S.R. Shaw. 1978. A note on the individuality of the intake of drinking water by dairy cows. Anim. Prod. 26:225-227. Loneragan, G.H., J.J. Wagner, D.H. Gould, F.B. Garry, and M.A. Thoren. 2001. Effects of water sulfate concentration on performance, water intake, and carcass characteristics of feedlot steers. J. Anim. Sci. 79:2941-2948. McKee, J.E. and H.W. Wolf, eds. 1963. Water Quality Criteria. 2nd ed. Resources Agency of California State Water Resources Control Board, Sacramento, CA. Niles, G.A., S. Morgan, W.C. Edwards. 2000. Sulfur-induced polioencephalomalacia in stocker calves. Vet. Human Toxicol. 42:290-291. NRC. 1996. Nutrient Requirements of Beef Cattle: 7 t h Revised Edition. Natl. Acad. Press, Washington, DC. Olkowski, A.A. 1997. Neurotoxicity and secondary metabolic problems associated with low to moderate levels of exposure to excess dietary sulphur in ruminants: a review. Vet. Human Toxicol. 39:355-360. Phipps, R.H., J.A. Bines, and A. Cooper. 1983. A preliminary study to compare individual feeding through Calan electronic feeding gates to group feeding. Anim. Prod. 36:544 (Abstr.) Provenza, F.D. and D.F. Balph. 1987. Diet learning by domestic ruminants: theory, evidence and practical implications. Appl. Anim. Behav. Sci. 18:211-232. Ralphs, M.H. and F.D. Provenza. 1999. Conditioned food aversions: principles and practices, with special reference to social facilitation. Proc. Nutr. Soc. 58:813-820. Ray, D.E. 1987. Influence of season, diet and water quality on feedlot performance of steer calves. J. Anim. Sci. 65(Suppl. 1):499. (Abstr.) Rolls, B.J. and E.T. Rolls. 1982. Thirst. Cambridge University Press, Cambridge, England. Roth, G.B. and P.J. Crittenden. 1934. Sulfates of sodium and magnesium on gastro-intestinal activity. Proc. Soc. Exp. Biol. Med. 32:91-94. Silanikove, N., E. Maltz, A. Halevi, and D. Shinder. 1997. Metabolism of water, sodium, potassium, and chlorine by high yielding dairy cows at the onset of lactation. J. Dairy Sci. 80:949-956. Smart, M.E., R. Cohen, D.A. Christensen, and C M . Williams. 1986. The effects of sulfate removal from the drinking water on the plasma and liver copper and zinc concentrations of beef cows and their calves. Can. J. Anim. Sci. 66:669-680. Sowell, B.F., M.E. Branine, J.G.P. Bowman, M.E. Hubbert, H.E. Sherwood, and W. Quimby. 1999. Feeding and watering behavior of healthy and morbid steers in a commercial feedlot. J. Anim. Sci. 77:1105-1112. Weeth, H.J. and D.L Capps. 1972. Tolerance of growing cattle for sulfate-water. J. Anim. Sci. 34:256-260. Weeth, H.J. and J.E. Hunter. 1971. Drinking of sulfate-water by cattle. J. Anim. Sci. 32:277-281. Weeth, H.J., D.S. Sawhne, and A.L. Lesperance. 1967. Changes in body fluids, excreta and kidney function of cattle deprived of water. J. Anim. Sci. 26: 418-423. Zinn, R.A., E. Alvarez, M. Mendez, M. Montano, E. Ramirez, and Y. Sehen. 1997. Influence of dietary sulfur level on growth performance and digestive function in feedlot cattle. J. Anim. Sci. 75:1723-1728. Zoeteman, B.C.J. 1980. Sensory Assessment of Water Quality. Pergamon Series on Environmental Science Volume 2. Pergamon Press, Exeter, England. 43 Chapter III - Magnesium Sulphate Affects Water Consumption and Drinking Behaviour of Beef Cattle Introduction Sulphate contamination of cattle drinking water is a recognized production concern that also raises problems for animal welfare. At and above concentrations of approximately 3000 ppm SO4, cattle typically lower their water consumption, reduce their DMI, and experience lowered weight gain (Embry et al., 1959; Weeth and Hunter, 1971; Loneragan et al., 2001). High-S04 water may also disrupt nutritional status (Smart et al., 1986; Zinn et al., 1997; Ivancic and Weiss, 2001) and gastrointestinal function (Harvey and Read, 1973). Dehydration (Embry et al., 1959) and the metabolic disorder PEM (Beke and Hironaka, 1991; Niles et al., 2000) have been observed in cattle given high-S04 water. Maximum recommended levels of SO4 in cattle drinking water are between 1000 ppm (CCREM, 1987) and 2500 ppm SO4 (Digesti and Weeth, 1976); grazing cattle are often exposed to water containing these or higher concentrations (Boila, 1988; Harper et al., 1997). Although both Na2S04 and MgS04 are prevalent in many water sources, research has mainly examined the effects of [\la2SO4 on cattle, and guidelines for maximum SO4 levels in cattle drinking water are generally based on this literature. However, Mg plays very different metabolic roles than Na, and the two cations have dissimilar effects on animal health (Roth and Crittenden, 1934; Addison, 1968; Frandson and Spurgeon, 1992). The well-known appetite for Na (Denton, 1982), and the lack of a similar appetite for Mg, could also influence the response of cattle to these two cations. Earlier work conducted for this thesis showed that cattle find MgS04 in drinking water more aversive than Na2S04 at high concentrations, as demonstrated by reduced water consumption over brief (2-d) periods. This experiment aimed to build on those findings by documenting the response to high levels of MgS04 over 21 d exposure periods. 44 Methods and Materials This research took place at Agriculture and Agri-Food Canada's Range Research Unit, located in Kamloops, British Columbia from June 13 to August 28, 2002. Average maximum, minimum and mean daily temperatures for this period were 28.7, 13.5 and 20.9°C, and average maximum and minimum RH were 72.8% and 26.8%, respectively. The research site was in a semi-arid environment with 36.6 mm precipitation during this trial, the majority (17.6 mm) falling in July. Experimental Design Sixteen yearling Hereford and Hereford * Angus steers and bred heifers (initial weight: 4 2 1 ± 24 kg, mean ± SD) were used, with eight animals of each gender. All animals had been raised as part of the same breeding herd and had spent the previous summer with their dams on rangeland in the Kamloops area where some natural water sources contain high levels of SO4. All animals had been used in a preference experiment, one month before this experiment, in which they were exposed to water containing SO4 at concentrations ranging from 0 to approximately 5000 ppm as either Na2S04 or MgS04. Animals were housed in two groups, one of eight steers and one of eight heifers, in pens that contained a combination of concrete and dirt flooring. Each pen had a shelter and communal feedbunk sufficiently large for all animals to feed at the same time. Orchardgrass hay (mean 9.7% CP, 91.4% DM, 0.20% S) was fed ad libitum and refreshed twice daily at 0700 to 0800 and 1400 to 1500. The hay also contained 0.03% Na and 0.14% Mg on a DM basis. The diet included ad libitum access to a cobalt iodized stock salt block composed of a minimum of 99.0% NaCI (Windsor; The Canadian Salt Company Limited) and mineral mix containing 10.0% Na, 2.0% Mg and 25.0% NaCI (Trail Blazer 1:1 Range Mineral for Beef Cattle with Selenium; New-Life Feeds, Lethbridge). 45 Access to water was controlled through the use of Calan headgates (American Calan Inc., Northwood, U.S.A.) which allowed each animal to drink from its own large transparent plastic container. Containers had marks on their sides denoting 2 L increments of volume. Access to water was limited to two drinking events per day at 1000 to 1130 and 1630 to 1730 daily. The length of access during each drinking event was not predetermined; instead, a drinking event was considered ended when all animals had stopped drinking and left the area of the headgates and water containers. Once this happened, headgates were locked and covers put on the containers to prevent access to water until the next scheduled drinking event. After each drinking event, water consumption was noted to the nearest 1 L, and containers were refilled to up to 30 L with the appropriate water treatment. Containers were emptied, scrubbed and refilled every second day. Two animals of each gender were randomly allocated to each of the four treatments: tapwater, N a 2 S 0 4 at 2000 ppm S 0 4 ("low Na 2 S 0 4 " ) , M g S 0 4 at 2000 ppm S 0 4 ("low MgS0 4"), or M g S 0 4 at 4000 ppm S 0 4 ("high MgS0 4 "). Solutions were prepared by mixing ACS grade (> 99.0% purity) anhydrous Na2S0 4 , M g S 0 4 heptahydrate or K2SO4 with tapwater by weight to make up the target S 0 4 concentration. Actual S 0 4 concentrations determined by analysis (see below) were 16, 1958, 2012 and 4060 ppm, respectively. After the animals had been on their respective treatments for 21 d, they were placed on tapwater for 7 d to minimize carryover effects, and were then exposed to the next treatment for an additional 21 d. This cycle was repeated for a total of 3 times, so that each animal was exposed to 3 of the 4 potential treatments in an incomplete Latin Square design. Fecal samples were taken by rectal grab sampling on d 1, 11 and 21 of each treatment period at approximately the same time in the morning, before the first drinking event of the day. Samples were immediately weighed and dried at 60°C for 48 h. 46 Hay samples were taken daily and pooled by 21-d treatment period. Samples were analyzed for CP by micro-Kjeldahl, for Mg and Na content by atomic absorption spectrophotometry and for S using nitric-perchloric acid digests by ICP emission spectrometry. Dry matter was determined by drying samples at 60°C for 48 h. Water samples (10 ml) were taken the morning of every second day after containers had been refilled, and were pooled according to treatment within animal. Samples were analyzed for SO4 by the turbidimetric method. (AOAC, 1990) and for Na and Mg by atomic absorption spectrophotometry: Animals were monitored daily for changes in health status through visual observation for excessive weight loss and symptoms of PEM such as loss of coordination. A review of the literature suggested that cattle of the same age and physiological status as the animals used in this trial can fully recover from 4 d of water deprivation (Weeth et al., 1967). Therefore, in order to maintain animal health, daily water consumption was closely monitored and on the one occasion when an animal failed to consume the offered water for 3 d (6 drinking events) it was offered tapwater and discontinued on that treatment. Data Analysis Water intake values were graphed over each 21-d treatment period to visually assess any time trends. Lack of such trends, plus the fact that water consumption by individuals can vary significantly between days (Little and Shaw 1978), suggested that data could be pooled for each treatment period. A single mean daily water consumption value was therefore used for each animal on each treatment. Due to the unbalanced design, each animal was exposed to 3 of the 4 treatments, yielding 12 animals per treatment and eight animals for each pair-wise comparison of treatments. Effects of treatment on average daily water consumption and fecal DM content were tested using general linear model and least squares means procedures of SAS (SAS Inst. Inc., Cary, NC). Fecal DM values for Day 1 47 (before start of treatment) were compared to Day 11 (middle of treatment period) and Day 21 (end of treatment period) with Day 1 fecal DM as a covariate. Graphical analysis in Excel (Microsoft Corporation, Redmond, WA) showed large differences between treatments in the variability of water consumed from one drinking event to another, with some animals failing to drink at some drinking events ("refusals"). This behaviour was captured in two ways: (1) the standard deviation of the consumption was calculated for each animal in each treatment based on the 42 drinking events, and (2) the number of refused drinking opportunities was counted for each animal in each treatment. Wilcoxon paired-sample tests were used to test variability in water consumption patterns by comparing the standard deviation of water consumption over the 21-d treatment period for each animal. The number of refusals during each treatment period was compared using paired t-tests. To reduce the likelihood of spurious significant differences owing to a large number of comparisons, only three specific treatment comparisons were tested: (1) tapwater vs. low MgS0 4 , (2) low M g S 0 4 vs. high MgS0 4 , and (3) low N a 2 S 0 4 vs. low MgS0 4 . The first two comparisons tested the key hypothesis that M g S 0 4 affects the water consumption, fecal DM and drinking behaviour of cattle. The low (\la2SO4 treatment was included as a reference point to the majority of S 0 4 literature where Na2S0 4 is the source of S 0 4 , with the final comparison testing the null hypothesis tha tMgS0 4 and Na2S0 4 have similar effects on water consumption, fecal DM and drinking behaviour at approximately 2000 ppm S 0 4 . Results Average daily water consumption was greater for tapwater than for the three S 0 4 -water treatments (Figure 3-1). The three planned pair-wise comparisons showed that average daily consumption of low Na2S0 4 and low MgS0 4-water was not different (P > 0.05); however, consumption of low MgS0 4-water was lower than that of tapwater (P < 0.01), and 48 consumption of high MgSO-4-water was lower than that of low MgS0 4-water (P < 0.01) (Figure 3-1). 49 a S c — re o. a E V 3 O) |2 2 o < o . SJJ If Q </> re o •o >-c fl> « re o o w re w >i re Q * J re re o a> 40 30 20 10 0 10 0 10 0 16 12 8 4 * * ! i Tapwater Low Na Low Mg High Mg Treatment Figure 3-1. Mean ± SEM of the four measures based on 12 animals in each of the four treatments: (1) average daily water consumption, (2) standard deviation of water consumption of each animal over 42 drinking events, (3) number of drinking events (maximum = 42) when the animal refused to drink, and (4) fecal DM at d 21. Horizontal bars show the three specific comparisons tested by pair-wise comparisons with n = 8 animals per pair. * P<0.05, ** P<0.01. 50 When offered SCvwater, animals generally showed high variation in consumption between drinking events, sometimes refusing to drink at all. For example, in the high MgSCU treatment, animals often refused to drink or drank relatively small amounts at individual drinking events (Figure 3-2C); refusals and low intakes were less common in the low Na2S04 and low MgSCM treatments (Figure 3-2B), and rare when tapwater was provided (Figure 3-2A). In this figure, three different animals were chosen to most clearly present the drinking behaviour patterns differences identified through statistical analysis. The mean of the standard deviations in consumption and mean refusals showed clear increases at higher SO4 levels (Figure 3-1). For both refusals and standard deviation between drinking events, the planned comparisons showed that these variables did not differ between the low N a 2 S C " 4 and low MgSCM treatments, that animals had the fewest refusals and smaller standard deviation for tapwater compared to low MgSCU, and fewer refusals and smaller standard deviation for low MgSCM compared to high MgSC>4. 51 1 3 5 7 9 11 13 15 17 19 21 Day Figure 3-2. Examples of the variation in water consumption over the 42 drinking events (2 per day). A: When given tapwater, animal #118 consumed water at every drinking event, usually between 15 and 30L. B: When given 2000 ppm S 0 4 as MgS0 4 , animal #104 failed to drink in seven events and consumed < 15 L in six others. C: When given 4000 ppm S 0 4 as rvlgS04, animal #121 drank < 15 L in 10 events and refused to drink in another 23. 52 After 21 d on treatment, fecal DM content was greater (P = 0.03) for high MgS04 than low MgS04 (Figure 1). This difference was not apparent at d 11 (P = 0.22) or between any of the other treatments at d 11 or d 21. No instances of compromised animal health were recorded during this study; however, one animal was removed from the high MgS04 treatment on d 10, after 6 consecutive drinking events where her consumption was less than 3 L/drink. Upon receiving tapwater, this animal's average daily consumption rose to 42 L/d, well within acceptable levels. Discussion The response to drinking water containing low Na2S04 (2000 ppm SO4), low MgS04 (2000 ppm SO4) or high MgS04 (4000 ppm SO4), seen in this trial is consistent with previous work undertaken as part of this thesis and with earlier studies showing that water consumption was not affected at 2000 (Robertson et al., 1996) or 2500 (Digesti and Weeth, 1976) ppm S 0 4 . At higher SO4 concentrations of 3493 (Weeth and Hunter 1971) and 4000 ppm (Harper et al. 1997), water consumption was depressed by 35 and 40%, respectively; in this experiment, average daily water consumption was depressed by 44% when animals were given high MgS04 compared to tapwater. It appears that between 2000 and 4000 ppm SO4 a threshold is reached beyond which water consumption and other variables are negatively affected; other authors (Weeth and Capps, 1972; Digesti and Weeth, 1976) have suggested a similar range. Apart from reduced consumption, there is other evidence that cattle find SO4 aversive at approximately 2000 ppm (as both Na2S0 4 and MgS04) as well as 4000 ppm (as MgS04). Some variation in consumption between drinking events was anticipated, if only because of the well known diurnal variation in drinking and feeding behaviour (Sneva 1970; Dulphy et al., 1980). However, the large increase in variability in consumption with SO4-water has not been reported previously. The fact that cattle did not drink at all on some 53 occasions suggests there is indication of a change in the motivational level required for the animal to drink. Thirst is recognized as the strongest physiological drive after those for air and severe pain (Fitzsimons, 1979). A skipped drinking opportunity suggests that the animal's level of thirst, which almost always led to drinking tapwater, was not great enough to overcome SO4 aversion; instead, cattle may skip a drinking event and thus would be expected to be thirstier for subsequent events. Because SO4 salts, particularly MgS04, are known to have purgative effects (McKee and Wolf 1963, Harvey and Read 1973, Fraser et al. 1991), it was expected that their presence in water would result in an increase in fecal moisture. For example, Embry et al. (1959) observed scouring in cattle given high-SO-4 water. However, the fecal DM content actually increased after 21 d of exposure to high MgSCU, presumably because of the lower water intake on this treatment. When cattle experience water restriction or deprivation, one of the first physiological responses noted is a decrease in the water content of fecal material (Thornton and Yates 1968, Little et al. 1976). NRC (1996) suggests that cattle such as those used in this study require approximately 4 1 L of water daily; however, average daily consumption of water containing 4000 ppm SO4 was only 26.3 ± 1.9 L/d. This low consumption may have been enough to cause reduced fecal moisture sufficient to outweigh any purgative effects of MgS04. Indeed, the purgative effects of MgS04 early in the 21-d treatment periods may have accentuated the evidence of subsequent dehydration as water consumption declined. In this experiment, we used MgS04 as the source of S 0 4 at 4 0 0 0 ppm because previous thesis work suggested that cattle find it more aversive than Na2S04. With a documented effect of S 0 4 on water consumption (Weeth and Hunter, 1971; Loneragan et al., 2001), it is now important to further explore the role that Mg plays in the reduced water consumption, fecal DM changes and behavioural responses observed in this study. When 54 Weeth and Hunter (1971) compared the reaction of cattle to water containing either Na2S04 or NaCI, they were able to isolate the effect of SO4 from that of the cation by demonstrating that water consumption was reduced when it contained Na2S04 instead of NaCI. This same approach could be used with MgSO-4 and MgCb to investigate the relationship between Mg, S 0 4 , and their effects on water consumption, fecal DM and drinking behaviour. Further studies could also assess composition and consumption data for feed, mineral supplements and water sources to calculate total Mg intake. This approach would allow for comparison with suggested upper tolerance levels for cattle (NRC, 1996) and examination of what role (if any) Mg toxicity plays in response to MgS04. In this study, estimated daily intake of Mg was approximately 0.35% of DMI for the low MgS04 treatment and 0.4% of DMI for the high MgS04 treatment; NRC guidelines (1996) suggest that these values are equal to or below maximum acceptable concentrations. The reduced water consumption, increase in fecal DM and changes in drinking behaviour indicate that high levels of MgS04 in drinking water pose a problem for cattle; in particular, water containing greater than 3000 ppm SO4 should be avoided. When water consumption is reduced, feed intake is depressed (Bond et al., 1976); hence, it is reasonable to expect lower feed intake and weight gains when animals are exposed to SO4-water for extended periods as may occur with cattle grazing on rangeland in semi-arid regions. High S04-water is also animal welfare concern as those cattle skipping opportunities to drink presumably experienced increased thirst. 55 References Addison, J.M. 1968. Harmful levels of magnesium salts are not uncommon. J. Agric. 66:468-469. AOAC. 1990. Method 973.57: Sulfate in water -turbidimetric method. Pages 330-331 in Official Methods of Analysis. 15th ed. Assoc. Offic. Anal. Chem., Arlington, VA. Beke, G.J. and R. Hironaka. 1991. Toxicity to beef cattle of sulfur in saline well water: a case study. Sci. Total Environ. 101:281-290. Boila, RJ . 1988. The sulfate content of water for cattle throughout Manitoba. Can. J. Anim. Sci. 68:573-576. Bond, J., T.S. Rumsey, and B.T. Weinland. 1976. Effect of deprivation and reintroduction of feed and water on the feed and water intake behavior of beef cattle. J. Anim. Sci. 43:873-878. CCREM. 1987. Canadian Water Quality Guidelines. Canadian Task Force on Water Quality: Agricultural Uses - Livestock Watering. Canadian Council of Resource and Environment Ministers, Ottawa, ON. Denton, D. 1982. The Hunger for Salt. Springer-Verlag, New York, NY. Digesti, R.D. and H.J. Weeth. 1976. A defensible maximum for inorganic sulfate in drinking water of cattle. J. Anim. Sci. 42:1498-1502. Dulphy, J.P., B. Remond, and M. Theriez. 1980. Ingestive behaviour and related activities in ruminants. Pages 103-122 in Y. Ruckebusch and P. Thivend, eds. Digestive Physiology and Metabolism in Ruminants: Proceedings of the 5th International Symposium on Ruminant Physiology, held at Clermont-Ferrand, on 3rd-7th September, 1979. MTP Press Limited, Lancaster. 56 Embry, LB. , M A Hoelscher, R.C. Wahlstrom, C.W. Carlson, L M . Krista, W.R. Brosz, G.F. Gastler, and O.E. Olson. 1959. Salinity and livestock water quality. S. Dakota Agr. Exp. Sta. Bull. 481. Brookings, SD. Fitzsimons, J.T. 1979. The Physiology of Thirst and Sodium Appetite. Cambridge University Press, Cambridge. Frandson, R.D. and T .L Spurgeon. 1992. Anatomy and Physiology of Farm Animals. 5 t h ed. Lippincott Williams & Wilkins, Media, PA. Fraser, C M . , J.A. Bergeron, A. Mays, and S.E. Aiello, eds. 1991. Page 1382 in The Merck Veterinary Manual. 7th ed. Merck & Co., Rahway, NJ. Harper, G.S., T J . King, B.D. Hill, C.M.L. Harper, and R.A. Hunter. 1997. Effect of coal mine pit water on the productivity of cattle II. Effect of increasing concentrations of pit water on feed intake and health. Aust. J. Agric. Res. 48:155-164. Harvey, R.F. and A.E. Read. 1973. Saline purgatives act by releasing cholecystokinin. Lancet. 2(1):185-187. Ivancic, J. Jr. and W.P. Weiss. 2001. Effect of dietary sulfur and selenium concentrations on the selenium balance of lactating Holstein cows. J. Dairy Sci. 84:225-232. Little, W., B.F. Sansom, R. Manston, and W.M. Allen. 1976. Effects of restricting the water intake of dairy cows upon their milk yield, body weight and blood composition. Anim. Prod. 22:329-339. Little, W. and S.R. Shaw. 1978. A note on the individuality of the intake of drinking water by dairy cows. Anim. Prod. 26: 225-227. Loneragan, G.H., J.J. Wagner, D.H. Gould, F.B. Garry, and M A Thoren. 2001. Effects of water sulfate concentration on performance, water intake, and carcass characteristics of feedlot steers. J. Anim. Sci. 79:2941-2948. 57 McKee, J.E. and H.F. Wolf., eds. 1963. Water Quality Criteria. 2nd ed. The Resources Agency of California State Water Resources Control Board Pub. 3-A. Sacramento, CA. Niles, G.A., S. Morgan, W.C. Edwards, and D.L Lalman. 2000. Effects of increasing dietary sulfur concentration on the incidence and pathology of polioencephalomalacia in weaned beef calves. Pages 55-60 in Okla. State Univ. Res. Rep. Oklahoma, OK. NRC. 1996. Nutrient Requirements of Beef Cattle: 7th Revised Edition. Natl. Acad. Press, Washington, DC. Robertson, B.M., T, Magner, A. Dougan, M.A. Holmes, and R.A. Hunter. 1996. The effect of coal mine pit water on the productivity of cattle. I. Mineral intake, retention, and excretion and the water balance in growing steers. Aust. J. Agr. Res. 47:961-974. Roth, G.B. and P.J. Crittenden. 1934. Sulphates of sodium and magnesium on gastro-intestinal activity. Proc. Soc. Exp. Biol. Med. 32:91-94. Smart, M.E., R. Cohen, D.A. Christensen, and C M . Williams. 1986. The effects of sulphate removal from the drinking water on the plasma and liver copper and zinc concentrations of beef cows and their calves. Can. J. Anim. Sci. 66:669-680. Sneva, F.A. 1970. Behavior of yearling cattle on eastern Oregon range. J. Range Manage. 23:155-157. Thornton, R.F. and N.G. Yates. 1968. Some effects of water restriction on apparent digestibility and water excretion of cattle. Aust. J. Agr. Res. 19:665-672. Weeth, H.J. and D.L. Capps. 1972. Tolerance of growing cattle for sulfate-water. J. Anim. Sci. 34:256-260. Weeth, H.J. and J.E. Hunter. 1971. Drinking of sulfate-water by cattle. J. Anim. Sci. 32:277-281. Weeth, H.J., D.S. Sawhne, and A.L. Lesperance. 1967. Changes in body fluids, excreta and kidney function of cattle deprived of water. J. Anim. Sci. 26:418-423. Zinn, R.A., E. Alvarez, M. Mendez, M. Montano, E. Ramirez, and Y. Sehen. 1997. Influence of dietary sulfur level on growth performance and digestive function in feedlot cattle. J. Anim. Sci. 75:1723-1728. 59 Chapter IV - Conclusions This research has shown that Na2S04 and MgS04 affect a variety of parameters associated with the drinking behaviour of beef cattle. A decline in water consumption with increasing SO4 content has been well documented in studies where the primary source of S 0 4 was N a 2 S 0 4 (Embry et al., 1959; Weeth and Hunter, 1971; Harper et al., 1997). For this work, the focus shifted to MgSCU because many standing surface water bodies such as ponds and dugouts in the Kamloops region contain higher levels of Mgthan Na (Appendix I). While lower (at and below approximately 3000 ppm) SO4 concentrations did not elicit a uniform response, high (approximately 4700 ppm) S 0 4 concentrations of both compounds resulted in reduced average daily water consumption. In the two experiments where SO4 concentrations increased, cattle appeared to find MgS04 more aversive than Na 2S04, as shown through a stronger negative dose response to the former compound. Given the fact that Mg and Na fulfill very different physiological roles (NRC, 1996), the phenomenon of Na appetite in herbivores (Denton, 1982), and the close link of Na to thirst mechanisms (Fitzsimons, 1979), it is not surprising that cattle responded differently to these cations in their water supply., Sulphate at high concentrations has been shown to depress water consumption, feed intake and weight gain (Weeth and Hunter, 1971; Weeth and Capps, 1972; Patterson et al., 2002), interact with other minerals (Smart et al., 1986) and negatively affect carcass characteristics (Loneragan et al., 2001). At sufficiently high concentrations in these experiments, both SO4 salts were responsible for decreased water consumption, confirming the role of SO4 in these effects. However, the stronger negative response to MgS04 suggests that the cation also plays a role in the perception of water quality by cattle, meriting further investigation so that guidelines for acceptable levels of SO4 in drinking water can accurately reflect cattle response to different SO4 salts. 60 Throughout these experiments, the response to SO4 compounds in water was highly variable, with some animals drastically reducing their water consumption in the presence of SO4 salts, and others demonstrating only moderate declines. Research suggests that aversion thresholds to compounds dissolved in water vary in humans (Zoeteman, 1980), and Goatcher and Church (1970) showed a wide range in aversion thresholds in ruminants given water containing acetic acid. Such variation could be due to random biological variation (Goatcher and Church, 1970), genetic parameters (Bell and Williams, 1959; Fischer, 1967), and various other animal- and environmental-based factors (McKee and Wolf, 1963; Ray, 1987). This variation has implications for the management of cattle because a watering site that is suitable for some cattle may not be suitable for all and therefore selection of such sites should be made keeping those more sensitive animals in mind. Fecal DM increased after 2 1 d of exposure to water containing 4 0 6 0 ppm SO4 as MgS04, demonstrating that this compound can potentially disrupt normal functioning of the gastro-intestinal tract. This effect can likely be attributed to dehydration resulting from significant reduction in water consumption rather than S 0 4 per se; similarly Weeth et al. (1967) and Thornton and Yates (1968) observed reductions in the amount of water lost through fecal material when cattle were deprived of or had restricted access to water. The absence of this finding under shorter treatment durations (7 and 11 d) and lower SO4 concentrations suggests that time and amount of SO4 ingested play important roles in determining the effect of SO4 on digestive functioning. It is unclear, however, how the effects seen in this study would affect animals under production conditions. Although there is some evidence that cattle can acclimate to S0 4-water under gradual introduction, this ability appears to be limited to SO4 concentrations at or below 2000 ppm (Robertson et al., 1996). At the higher concentrations explored in this study, long-term exposure has been 61 linked to the reduced productivity described above, as well as to the development of PEM (Harries, 1987) and death (Patterson et al., 2003). The health-related effects of high-S04 water have obvious implications for animal welfare. In addition, increased latency to drink S04-water suggests that animals must be thirstier to drink such water when compared to tapwater. Hence, animal welfare may also be affected by increased thirst or frustrated attempts to alleviate thirst. The findings raise new questions regarding the role of the cation-S04 complex in the acceptability of this water by cattle, individual variation with respect to aversion thresholds for these compounds, and the applicability of these findings to production situations on rangeland. As described in Chapter III, continued work with MgS04 and other Mg-anion compounds could be used to tease apart the relative effects of the cation and anion, in a manner similar to that used by Weeth and Hunter (1971) to separate the effects of Na from those of SO4. Assessment of total Mg, Na and S0 4 intake could be used to determine whether toxicity to either of these minerals plays a role in the response. Experiments specifically designed to assess individual variation in response to SO4 salts could provide a clearer picture of how this variation affects production and animal welfare. Additionally, testing the response to these compounds under range conditions, such as group watering, would strengthen the applicability of these findings to production situations. In summary, this research demonstrates that the SO4 salts MgS04 and Na2S04 are aversive to cattle at certain concentrations. While lower concentrations (below approximately 3 0 0 0 ppm SO4) do not appear to consistently affect variables such as average daily water consumption, concentrations of approximately 4000 ppm S0 4 and above result in dramatic reductions in water consumption, shifts in water balance, and changes in drinking behaviour. Existing guidelines promoting 1000 ppm as the maximum acceptable SO4 concentration in cattle drinking water (CCREM, 1987) appear to be 62 sufficiently conservative to avoid negative effects on cattle. However, as other authors (Digesti and Weeth, 1976; Harper et al., 1997) have suggested these recommendations may be too conservative, it is possible that future guidelines will cite higher SO4 concentrations as acceptable. In that case, it will be important that such guidelines acknowledge that MgS04 appears to be more aversive than Na2S04, necessitating cation specific guidelines for SO4 content in cattle drinking water. Additionally, recommendations for maximum acceptable SO4 levels will need to be sufficiently conservative to take into account individual variation in aversion thresholds and other factors such as total dietary S intake in order to avoid welfare and production consequences. Finally, this research has shown that cattle producers need to be aware of the mineral content of the water they provide to their cattle, and that decisions regarding which natural water bodies to use as watering sources - either through controlled direct access, or off-site pumps - should be made with information such as that provided through this research. 63 References Bell, F.R. and H.L Williams. 1959. Threshold values for taste in monozygotic twin calves. Nature. 4657:345-346. CCREM. 1987. Canadian Water Quality Guidelines! Canadian Task Force on Water Quality: Agricultural Uses - Livestock Watering. Canadian Council of Resource and Environment Ministers, Ottawa, ON. Denton, D. 1982. The Hunger for Salt. Springer-Verlag, New York, NY. Digesti, R.D. and HJ . Weeth. 1976. A defensible maximum for inorganic sulfate in drinking water of cattle. J. Anim. Sci. 42:1498-1502. Embry, LB. , M.A. Hoelscher, R.C. Wahlstrom, C.W. Carlson, L M . Krista, W.R. Brosz, G.F. Gastler, and O.E. Olson. 1959. Salinity and livestock water quality. S. Dakota Agr. Exp. Sta. Bull. 481. Brookings, SD. Fischer, R. 1967. Genetics and gustatory chemoreception in man and other primates. Pages 61-81 in The Chemical Senses and Nutrition. M.R. Kare and 0. Mailer, eds. The Johns Hopkins Press, Baltimore, MD. Fitzsimons, J.T. 1979. The Physiology of Thirst and Sodium Appetite. Cambridge University Press, Cambridge. Goatcher, W.D. and D.C. Church. 1970. Taste responses in ruminants. IV. Reactions of pygmy goats, normal goats, sheep and cattle to acetic acid and quinine hydrochloride. J. Anim. Sci. 31:373-382. Harper, G.S., T J . King, B.D. Hill, C.M.L. Harper, and R.A. Hunter. 1997. Effect of coal mine pit water on the productivity of cattle II. Effect of increasing concentrations of pit water on feed intake and health. Aust. J. Agric. Res. 48:155-164. Harries, W.N. 1987. Polioencephalomalacia in feedlot cattle drinking water high in sodium sulfate. Can. Vet. J. 28:717. (Abstr.) 64 Loneragan, G.H., J.J. Wagner, D.H. Gould, F.B. Garry, and M.A. Thoren. 2001. Effects of water sulfate concentration on performance, water intake, and carcass characteristics of feedlot steers. J. Anim. Sci. 79:2941-2948. McKee, J.E. and H.W. Wolf, eds. 1963. Water Quality Criteria. 2nd ed. Resources Agency of California State Water Resources Control Board, Sacramento, CA. NRC. 1996. Nutrient Requirements of Beef Cattle: 7th Revised Edition. Natl. Acad. Press, Washington, DC. Patterson, H.H., P.S. Johnson, and W.B. Epperson. 2003. Effect of total dissolved solids and sulfates in drinking water for growing steers. J. Anim. Sci. 81(Suppl. 1):80. (Abstr.) Patterson, H.H., P.S. Johnson, T.R. Patterson, and D.B. Young. 2002. Effects of water quality on performance and health of growing steers. J. Anim. Sci. 80(Suppl. 2):113. (Abstr.) Ray, D.E. 1987. Influence of season, diet and water quality on feedlot performance of steer calves. J. Anim. Sci. 65(Suppl. 1):499. (Abstr.) Robertson, B.M., T. Magner, A. Dougan, M.A. Holmes, and R.A. Hunter. 1996. The effect of coal pit mine water on the productivity of cattle. I. Mineral intake, retention, and excretion and the water balance in growing steers. Aust. J. Agric. Res. 47: 961-974. Smart, M.E., R. Cohen, D.A. Christensen, and C M . Williams. 1986. The effects of sulphate removal from the drinking water on the plasma and liver copper and zinc concentrations of beef cows and their calves. Can. J. Anim. Sci. 66:669-680. Thornton, R.F. and N.G. Yates. 1968. Some effects of water restriction on apparent digestibility and water excretion of cattle. Aust. J. Agr. Res. 19:665-672. Weeth, H.J. and D.L. Capps. 1972. Tolerance of growing cattle for sulfate-water. J. Anim. Sci. 34:256-260. Weeth, HJ . and J.E. Hunter. 1971. Drinking of sulfate-water by cattle. J. Anim. Sci. 32:277-281. Weeth, HJ. , D.S. Sawhne, and A.L. Lesperance. 1967. Changes in body fluids, excreta and kidney function of cattle deprived of water. J. Anim. Sci. 26:418-423. Zoeteman, B.C.J. 1980. Sensory Assessment of Water Quality. Pergamon Series on Environmental Science Volume 2, Pergamon Press, Exeter. 66 Appendix I - Summary of mineral content in ponds and dugouts in the Kamloops region The majority of SO4 research has used Na2SC>4 to examine the effects of SO4 on water and feed consumption, productivity, animal health and other variables (Embry et al., 1959; Weeth and Hunter, 1971). However, sampling of surface waters in the area of Kamloops and Merritt, British Columbia, indicated that many contain higher levels of Mg than Na, suggesting that cattle response to SO4 in these areas may be driven by MgS04 rather than Na2SC-4. Therefore, the research conducted for this thesis focused on the role of MgS04 in response to SO4 in cattle drinking water. The values presented in the table below provide examples of the mineral content of water sources that cattle grazing in these regions might be expected to encounter. Samples were obtained from 1999 - 2001 by D. Veira, L. Liggins and L. Stroesser of the M F C Range Research Unit. Solute Concentration, ppm Sample Location Date Sampled PH TDS S 0 4 Na K Mg Ball Lake 1 7/9/1999 9.66 6600 4980 37 20 612 Transect Lake 7/9/1999 8.73 601 115 1688 618 130 Muskrat Lake 7/9/1999 9.21 310 45 27 29 17 Muskrat Dugout 1 7/9/1999 9.24 145 178 5 18 11 Dam Lake 7/9/1999 9.95 4950 4980 2403 211 203 Beresford Dugout 14/9/1999 8.46 4290 3810 1654 136 1060 Beresford Pumped 14/9/1999 8.64 4554 3490 2120 143 1134 Beresford Dugout 17/08/2000 8.92 n/a 11721 3425 < 0.01 2320 Bat Lake 17/08/2000 9.68 n/a 106 568 < 0.01 9 Ball Lake 17/08/2000 9.54 n/a 63243 20725 3686 2448 67 Solute Concentration, ppm Sample Location Date Sampled pH TDS SO4 Na K Mg Transect Lake 17/08/2000 8.13 n/a 174 507 125 7 Dam Lake 17/08/2000 10.19 n/a 6025 2194 411 566 NE Dam (lake unknown) 17/08/2000 10.23 n/a 1094 933 174 5 Staple Lake 17/08/2000 9.18 n/a 1720 1033 210 268 Separation Lake 21/08/2000 9.06 n/a 1108 709 167 119 Lake #54 27/08/2000 9.25 n/a 1106 843 120 32 Lake SE of #54 27/08/2000 9.79 n/a 492 453 96 44 Lake #58 1 27/08/2000 9.07 n/a 4324 781 163 944 Long Lake (#61) 1 27/08/2000 8.73 n/a 5445 903 183 1262 Lake #207 1 27/08/2000 8.69 n/a 16980 1914 284 4542 Lake #208 1 27/08/2000 8.07 n/a 10932 1073 136 3518 Island Lake (#57) 27/08/2000 9.03 n/a 6757 2364 436 2217 Lake WSW of Mirror Lake 27/08/2000 9.46 n/a 367 769 142 334 Mirror Lake 1 27/08/2000 9.07 n/a 6863 1711 296 1834 Lac Du Bois (#48) 27/08/2000 • 8.85 n/a 113 440 92 8 Lake #185 27/08/2000 8.56 n/a 1123 502 155 366 Batchelor Lake (#188) 1 27/08/2000 8.86 n/a 5907 868 189 1687 Lake #52 21/09/2000 8.82 n/a 3446 1304 <0.02 507 Lake #56, Pipe Inflow 1 21/09/2000 8.25 n/a 131 29 12 104 Lake #9 1 21/09/2000 8.81 n/a 20785 3327 < 0.02 4093 Lake #214 21/09/2000 8.91 n/a 15064 3209 < 0.02 2298 Lake #205 1 21/09/2000 8.97 n/a 23184 2364 < 0.02 4574 Solute Concentration, ppm Sample Location Date Sampled PH TDS S0 4 Na K Mg Trough NE of Lake #205! 21/09/2000 7.78 n/a 1232 73 15 374 Lake #186! 21/09/2000 8.91 n/a 3335 < 0.3 90 760 Lake #184 21/09/2000 9.81 n/a 582 898 50 169 Lake #53 21/09/2000 9.88 n/a 4668 5355 < 0.02 154 Grace Lake (#64) 1 25/09/2000 8.79 n/a 6357 980 < 0.02 1505 Long Lake, edge 1 12/07/2001 9.06 8720 5280 814 225 2077 Long Lake, middle 1 12/07/2001 9.02 8653 5213 704 200 1582 Lake #186, edge 1 12/07/2001 8.96 4990 2910 383 128 910 Lake #186, middle i 12/07/2001 8.90 4980 2933 482 161 1137 Batchelor Lake (#188), edge 1 12/07/2001 9.28 12100 7240 387 183 1873 Batchelor Lake (#188), middle 1 12/07/2001 9.02 11200 7370 462 200 2344 Lake #185, edge 1 12/07/2001 8.83 2900 1620 41 89 530 Lake #185, middle 1 12/07/2001 8.59 6890 1590 51 151 623 Lake #58, edge 1 12/07/2001 9.24 6200 4020 628 179 1841 Lake #58, middle 1 12/07/2001 9.08 7443 4473 748 213 1971 Lac Du Bois (#48) 1 12/07/2001 9.22 619 57 62 25 204 Lake #53 12/07/2001 10.07 13900 3880 1830 511 129 Grace Lake 1 12/07/2001 9.14 11700 6260 1341 460 2922 Lake #54 1 12/07/2001 9.77 2270 1000 388 82 440 Lake SE of Lake #54 12/07/2001 9.33 1814 570 140 55 42 Mirror Lake 1 12/07/2001 9.58 12300 7420 1411 297 2119 69 Solute Concentration, ppm Sample Location Date Sampled pH TDS SO4 Na K Mg Lake WSW of Mirror 1 2 / ° 7 / 2 0 0 1 9 5 Q 1 6 1 0 3 Q 1 216 71 444 L a k e 1 Lake #56, Pipe 12/07/2001 g 6 Q 6 g 3 1 2 4 26 9 110 Inflow 1 1 These water bodies contain higher concentrations of Mg than Na References Embry, L.B., M.A. Hoelscher, R.C. Wahlstrom, C.W. Carlson, L M . Krista, W.R. Brosz, G.F. Gastler, and O.E. Olson. 1959. Salinity and livestock water quality. S. Dakota Agr. Exp. Sta. Bull. 481. Brookings, SD. Weeth, H.J. and J.E. Hunter. 1971. Drinking of sulfate-water by cattle. J. Anim. Sci. 32:277-281. 70 

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