School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemA study of weight-loss and compensatory gain in sheep( 1971)Two experiments of similar nature were conducted. In the first experiment 49 Corriedale wethers at approximately 8 months of age were allocated to four experimental groups and, within groups, to various slaughter weights which were spaced at 5 kg intervals. Group I animals were fed ad libitum and slaughtered - over a body weight- range of 38 - 63 kg inclusive. Groups II and III animals were fed ad libitum until 48 kg body weight hereupon intake was restricted to achieve a body weight loss of 0.9 kg/week until body weights were reduced to 38.5 kg and 34.5 kg, respectively. Ad libitum feeding was then resumed and animals were slaughtered up to 63 kg body weight at the same weight intervals as in Group I. Group IV animals were fed ad libitum until 48 kg body weight and then, food was adjusted to maintain body weight at 48 kg. Four animals were slaughtered after 60 days and a further four after 120 days of maintenance of body weight. In the second experiment, 15 wethers of similar age, breed and nutritional history as those used in Experiment 1, were allocated to four slaughter groups in a treatment similar to that of Group III in Experiment 1. Four animals were slaughtered at 33 kg body weight at the beginning of the first period of ad libitum feeding; three animals slaughtered at 45.5 kg at the end of the first period of ad libitum feeding; three animals slaughtered at 33.5 kg at the end of the weight loss phase; and five animals slaughtered at 46.5 kg at the end of the second period of ad libitum feeding. The compensatory growth rates of animals in Groups II and III were greater than those of Group I in each of the successive 5.5 kg increments in body weight. By maintaining higher growth rates over the entire weight range, the largest animals of Groups I I and III were slaughtered at a similar age to those, of Group I. Similarly, in Experiment 2, the compensatory growth rates (Group VI) were greater than continuous growth rates (Group V) over the body weight range used in this experiment. The data was transformed to logarithms in order to use Huxley's (1932) allometric growth equation in the linear form for an analysis of covariance. During continuous growth (Groups I and V), the empty body weight (EBW) increased as a proportion of full body weight (FEW) whilst during the compensatory growth which followed weight loss (Groups II, III and VI) the proportion of EBW remained constant. At the same FEW the EBW of Groups I I and III was less than that of Group I. Similarly, the EBW of animals maintained at a constant body weight (Group IV) was less, at the same FBW, than that of Group I. Carcass weight (CW) increased as a proportion of EBW as EBW increased in Groups I and V but the proportion remained constant in Groups II, III and VI. At the geometric mean FEW, treatment did not affect CW. However, the apparent dressing percentage (CW / FBW x 100) was 2% less during compensatory growth compared with that during continuous growth. The carcass length of animals in Groups II, III and IV was greater than that of animals in Group I.
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ItemSome effects of botanical composition of pasture on the liveweight and wool production of sheep( 1972)Until recently, the main evidence on which to base pasture mixture. recommendations in Victoria, has been district experience and the results from dry matter ( "mowing") experiments. The grazing experiments described in this thesis, were initiated by Messrs. R. Twentyman, R. Newman, R. Allen and K. Maher of the Department of Agriculture during the period, 1960-196. Their aim was to develop some objective appreciation of the relative value for animal production of some of the sown and unsown species in Western district pastures. In addition to pasture species evaluation, they sought information on the relationship between pasture growth and animal production. Such information is needed so that Agrostologists can better evaluate the many pasture management factors (such as fertilizers, seeding rates, seed. treatments, herbicides, insecticides and defoliation treatments) that affect pasture growth and for which advice is frequently sought.
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ItemOestrogens, isoflavones and the oestrous cycle of the ewe( 1972)The experimental work presented in this Thesis was carried out while the author was a recipient of a Commonwealth Post Graduate Scholarship. The supervision of the experimental work in Chapters 3 to 6 inclusive was delegated to Mr. I.A. Cumming and his willing help, advice and collaboration is gratefully acknowledged. Material contained in these Chapters was obtained from experiments carried out at the S.S. Cameron Laboratory, State Research Farm, Werribee, Victoria. Chapters 7 and 8 report results of Field Trials conducted in collaboration with Mr. J.M. Obst and the Officers of the S.A. Department of Agriculture, and Drs. R.J. Lightfoot and J.F. Smith and the Officers of the W.A. Department of Agriculture, respectively. The experimental programmes in the latter two chapters were mainly financed by the Australian Wool Board Funds allocated to my supervisor, Dr. J.R. Goding. The material presented in Chapters 4, 6 and 8 has been presented to the meetings of the Australian Society for Reproductive Biology (ASRB), 1971, and the Fourth Asia and Oceania Congress of Endocrinology, N.Z., 1971. The abstracts are listed at the end of the Preface. The general facilities of the State Research Farm, Werribee were made available for these studies and the author wishes to thank the Officer in Charge of the S.S. Cameron Laboratory, Dr. P.D. Mullaney and the past Acting Officer in Charge, Mr. A.D. North. Thanks must also be offered to Mr. J.B. McPherson, Manager of the State Research Farm and his staff for assistance in the purchase, feeding and general management of the flocks of sheep used for these studies. I would like to acknowledge the help and support received from my supervisor, Dr. J.R. Goding during the past two years, but particularly to thank him for his invaluable assistance and encouragement during the preparation of this manuscript. Dr. J.M. Brown and her technical assistants Misses J. Fratantaro and E. Renden generously performed the majority of the LH assays. The progesterone assays were done with the assistance of Miss B. Sinnott and under the guidance of Mr. J.M. Obst of the S.A. Department of Agriculture. Mr. G.J. Gyory of the Victorian Department of Agriculture carried out the isoflavone analyses, and Mr. R. Jardine also of the Victorian Department of Agriculture carried out the statistical analyses. Most of the experimental procedures required labour 24 hours a day and this was willingly provided by Agricultural Officers of the Victorian Department of Agriculture. My thanks and appreciation to Messrs. R.W. Baxter, T. Howard, W.B.H. McGregor, A.W. Makin, R.A. Parr and A.H. Williams. Assistance for these experiments was also given to me by my colleagues, Dr. M.A.deB. Blockey, Mr. L.P. Cahill, Dr. M. Cain, Mr. J. Cerini, Mrs. M.E.D. Cerini, Mr. W.A. Chamley, Mr. I.A. Cumming, Miss M.A. Curtis and Miss B.J. Mole. Invaluable technical assistance was given by Mesdames D. Baxter, M. Perry and Misses J. Fratantaro, E. Renden and E. Wilson. A special thank you must be offered to Mr. P. Langdon for the outstanding technical assistance and generous help which made so much of this work possible. The photographic work was done by Mr. W. Douglas and Mr. D. Rizzoli. Mrs. H. Constable typed all the drafts of the Thesis and the final manuscript was typed by Mrs. Adele Dowling. My thanks to all who have assisted me over the last two years.
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ItemThe ability of sheep and goats to utilize crop by-products( 1977)Two digestibility trials and one feeding experiment were implemented. In the first digestibility trial sheep were fed rations of hay to which was added (w/w} 10%, 20% and 30% of rice bran, soybean meal and cassava respectively. The results showed that changes in digestibility were not directly proportional to the amount of the ingredient added, thus the individual analysis or digestibility of a single food does not necessarily indicate its feeding value in mixed diet. In the second trial the digestive efficiency of sheep and goats was compared when fed low, medium and high quality diets as represented by oat straw, meadow hay and sheep fattening pellets. For all practical purposes the sheep and goats were similar in their ability to digest all diets but there was some evidence to show that the goats made better use of crude protein in the oat straw and crude fibre in the pelleted diet. In the feeding experiment the same by-products that were used in the first digestibility trial were variously combined to investigate the best mixture for fattening sheep. The best liveweight gains were obtained from diets D2 and D3. D2 contained 33% hay, 30% rice bran, 25% cassava and 12% soybean meal.' D3 comprised 40% hay, 15% rice bran, 30% cassava and 15% soybean meal.
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ItemVariability in the intake of supplements by grazing sheep( 1979)Although the practice of feeding supplements to grazing animals is widespread through the world, its efficiency still deserves further study. Factors associated with the supplements themselves, the animals being fed, the environment, and the grazing diet being supplemented together constitute a set of variables which affects not only acceptance and intake, but also the nutritional and economic efficiencies of supplementary feeding. This study is concerned with the feeding of supplements to grazing sheep under temperate climatic conditions. Oat grain, hay and molasses-urea blocks (Barastoc, KMM Pty. Ltd., Melbourne) were used initially, but subsequent experiments were confined to the utilization of molasses-urea blocks. Only recently have researchers emphasized the importance of variability in supplement intake between individuals within a herd or flock and estimates of intake, with large ranges between animals, have now appeared in the literature. Langlands and Bowles (1976) considered that such wide variabilities in intake, limit the effectiveness of all forms of supplementation. However, little is known about the factors affecting variability in a group situation and few attempts have been made to identify the possible factors inducing such wide ranges of intakes in grazing animals. Arnold and Bush (1968) identified three types. of sheep: "shy-feeders", periodic non-feeders, and over indulgers". In some situations social dominance has been observed to affect responses to supplements (Franklin and Sutton, 1952; Wagnon, 1965; Squires and Daws, 1975) , and Arnold and taller (1974) correlated the intake of supplements with body weights of sheep. Chapter 1 of this thesis reviews the direct and indirect effects on animal performance of the main factors related to the feeding of supplements. Chapter 2 presents estimations of intake of three supplements, oats, hay, molasses-urea block, made with sheep in small paddocks. Results of behavioural observations and body measurements of the sheep are presented and discussed separately in Chapter 3. Chapter 4 provides an assessment of the acceptability of molasses-urea blocks by seven different flocks of grazing sheep on five private properties. The effects of confining sheep in yards on their acceptance of the blocks are also reported. Few studies have sought to determine whether management stratagems may improve the rate of adaptation of sheep to molasses-urea blocks and induce more uniform intakes between animals. Pilot trials described in Chapter 5 were conducted to identify possible management procedures that may be suitable for these purposes. Four such procedures were sufficiently encouraging to justify testing in a replicated experiment, which is described in Chapter 6. These treatments were imposed on sheep confined in yards and fed hay at a submaintenance levels. The investigations described in Chapter 7 utilised a different approach and are concerned with the behavioural aspects of learning, a topic which has been intensively studied with laboratory animals but only rarely with farm animals. The effects of offering molasses-urea blocks to lambs in the pre-weaning period are assessed in terms of their acceptance of blocks in later life. Inevitably only a few experimental possibilities and combinations have been assessed in the work reported in this thesis. Major attention was directed towards molasses-urea blocks because they induced wider variability in the responses by sheep than did hay or grain supplements . The blocks used were those manufactured by KMM Pty. Ltd., Melbourne, had a hard texture for protection against wet weather conditions and required animals to lick them rather than chew them. Variations in block formulation were not studied in the work described in this thesis and it remains possible that other types of block may have produced different results.
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ItemEffects of growth patterns on body composition and compensatory growth in sheep( 1977)The literature related to compensatory growth in ruminants, with particular reference to sheep, has been reviewed. An experiment was conducted which examined the effects of planned BW losses on growth rate, body composition, wool growth and nitrogen and energy utilisation of sheep when ad libitum feeding was resumed. Sheep were fed a pelleted ration throughout the experiment, and BW loss induced by reducing feed intake. Following developmental growth from 30 to 37.8 kg, Groups B and C lost 21% BW at 122 and 63 gd-1, respectively to reach 30.2 kg BW. Following developmental growth from 30 to 46.7 kg (Groups D and E), Group D lost 34% BW at 125 gd-1 to reach 30.8.kg BW, while Group E lost 23% BW at 157 gd-1 to reach 35.0 kg. Group A was a control group fed ad libitum throughout the experiment. When ad libitum feeding was resumed compensatory growth occurred in treatment groups for up to 10 kg recovery of BW. Group D showed the most persistent increases in growth rate compared with that of control sheep, however, above 50 kg BW there were no significant differences between groups in growth rate. Weight loss did not produce a reversal of the compositional changes which occurred with increasing BW during developmental growth, in the whole body, carcass or offal. However, differences in composition between groups at the end of weight loss were not significant. During compensatory growth there were few differences between groups in the relative growth rates of protein, fat, ash or water in the whole body, carcass or offal. There were some differences between groups in weights of components at specific BW, carcass weight (CW) and offal weight WW), most notably fat and ash. However, these differences appeared to be transitory, and reflected the composition of that portion of the animal at the start of realimentation, rather than an effect of weight loss which was maintained during compensatory growth. The body, carcass and offal composition of sheep appeared to be resilient to periods of nutritional stress, and tended to return to the "normal" composition expected at that weight. The effects of up to 18 weeks severe undernutrition, resulting in rapid BW loss, were able to be overcome during compensatory growth when feed was offered ad libitum. Compared with developmental growth, nitrogen retention increased during compensatory growth. However, the efficiency of ME utilization was not different during these two periods of growth, although DE requirements for maintenance were lower during compensatory growth, compared with developmental growth. Dry matter intakes (DMI) of treatment groups required up to 13 weeks to return to the DMI of sheep during developmental growth, once ad libitum feeding was resumed. Over their respective growth paths Groups A, B, C, D and E required the same amount of feed to reach 50 kg BW. Wool growth rate (WGR) responded more slowly than BW to changes in level of nutrition, both during weight loss and during compensatory growth. There was a lag phase of at least 30 days. WGR during compensatory growth was reduced and required up to 14 weeks to return to developmental WGR after ad libitum feeding was resumed. Total body water (TBW), estimated from tritiated water (TOH) space in sheep undergoing compensatory growth, was overestimated by at least 20%. TOH space was measured without imposing a period of prior starvation on the sheep, and this may have contributed to the large overestimate. Multiple regression equations including TOH space, BW and a maturity factor (M), were able to explain up to 95% of the variation in chemical composition of the body, but residual standard errors were still high.