School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemPasture utilization for wool growth of weaner sheep in south western Victoria( 1988)Two series of experiments are described in this thesis. The first set of experiments report on the use of young, oesophageally fistulated sheep to collect herbage samples in grazing experiments. Secondly, the biological responses of Merino and Comeback weaner sheep to changes in pasture type and season of birth are described. The experiments were conducted at the Pastoral Research Institute, Hamilton, Victoria during 1982-86, where the author is employed as a Science Officer by the Victorian Department of Agriculture and Rural Affairs. Chapters 4 and 5 report the effects of several variables on the chemical composition of oesophageal fistula samples and have been submitted for publication (see below). Mr. P.C. Flinn and Professor A.R. Egan have been included as co-authors of Chapter 4 due to their contribution to chemical analysis of samples, and to planning of the experiment respectively. Mr. P.C. Flinn and Mr. J.F. Heard have been included as co-authors due to their assistance during the experiment described in Chapter 5. Differences between the growth, composition and nutritive value of lucerne/subterranean clover and perennial ryegrass/subterranean clover pastures are reported in Chapter 6. (More detailed data on the growth and composition of the pastures is available on request to the author). The effects of these pastures on the productivity of autumn and spring born, Merino and Comeback weaner sheep are presented in Chapters 7 and 8. It. is intended to submit these three chapters for publication. Mr. R.L. Thompson and Dr. J.M. Obst will be. included as co-authors when the results reported in Chapter 7 are published. The experiments reported in this thesis make up part of a larger project (Sheep Production Systems) for which Mr. Thompson and Dr. Obst are responsible. However I accept full responsibility for the collection of all data, analysis of results and preparation of the manuscripts. In addition, I was responsible for the design of experiments reported in Chapters 4, 5, 6 and 8. Details of publications are as follows:- Chapter 4 : Saul, G.R., Flinn, P.C. and Egan, A.R. (1988). The effect of fasting, breed and sample size on the chemical composition of pasture samples from fistulated weaned lambs (submitted to Australian Journal of Experimental Agriculture). Chapter 5 : Saul, G.R., Flinn, P.C. and Heard, J.F. (1986). The nutritive value of roughages before and after mastication by oesophageally fistulated sheep. Proceedings Australian Society of Animal Production 16, 351-54.
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ItemFlystrike in sheep : producers' knowledge, opinions, and management methods( 1986)Blowfly strike was recorded as a serious problem of Australian sheep during the first decade this century, and has remained a problem ever since. The cost of control was estimated at $44 million in 1975-76, and rising each year (Brideoake 1979). Much of the present knowledge of blowfly biology and strike aetiology was gained in the 1920's and '30's, and by the end of the 1940's simple, cheap and effective procedures were recommended which reduced flystrike by about 90 per cent. In the early 1970's, flystrike still caused major problems. The pest species had not changed, and the original recommendations had not been universally adopted (Graham 1979). This two stage survey assessed awareness of flystrike management among sheep producers, identified some commonly used communication channels for strike control information, and identified and assessed the importance of some socio-psychological and communication factors inhibiting access to or use of strike control information. Communication strategies were suggested for overcoming ineffective use of strike control information. Producers had poor knowledge of theoretical aspects of strike aetiology and the blowfly life cycle, but were well aware of readily observable aspects. Thirty percent of producers used three-joint tails, and the remainder used sub-optimal lengths. The advantages of using three-joint tails were not obvious to producers using other tail lengths, or manifested in practice. There was no association between three-joint tails and expressions of easier or more flexible management, or indications that flystrike was less important in management decisions. Low awareness, and poor capitalisation of the established advantages of three-joint tails probably are barriers which impede extension efforts. Evidence suggested that managers of flocks smaller than 1500 (more than 60 per cent of Australian enterprises) did not aim to maximise net flock revenue. This would be an important and profound barrier to current. extension practice. Mulesing was much more common among larger flocks, and was paradoxically used as an adjunct of other preventative management. Consequently, the majority of Australian flocks were relatively unprepared for strike control, and mulesed flocks were disproportionately well prepared. Producers' assessment of information and its sources varied according to the type of information sought. Popular sources for tail length, mulesing and jetting equipment information included the Department of Agriculture. There is an opportunity for state extension services to work together with other identified sources to stimulate the process of information transfer, and to improve producers' understanding of the practical advantages of strike management recommendations.