School of Agriculture, Food and Ecosystem Sciences - Theses
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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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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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