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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ItemStudies on formaldehyde treated diets for lambs( 1972)In the first section of this thesis the literature relating to the uses of protected proteins fed to ruminants is reviewed. The second section describes an investigation into the effect of formaldehyde treatment of concentrate diets for lambs. The diets consisted essentially of wheat alone and wheat plus 10% linseed meal or 10% rapeseed meal, containing 11.2, 13.7 and 13.8% crude protein respectively. These were fed to 20 kg Corriedale lambs under feedlot conditions. The growth rates of the lambs fed the treated diets were higher than those fed the untreated diets in all cases, but the differences were not statistically significant. Feed intakes were highest with the diets containing linseed meal (P< 0.0 5) . The wool growth rates of lambs fed the treated diets were higher than those fed the untreated diets, but the difference was significant only in the case of the wheat diet (PC 0.05). Increasing the level of the protein meals in the diets to 20; (about 15.8% CP) resulted in increased rates of weight gain with the untreated diets but decreased weight gains and feed intakes in the case of the treated diets. At the higher protein level the feed intakes and growth rates of lambs fed the untreated linseed meal diet were greater (P< 0.05) than those of the lambs on the treated linseed meal diet. No other differences between treated and untreated diets were significant. Investigation into methods of applying formalin to hammermilled wheat showed that neither the dilution of the applied formalin nor the air temperature at the time of application had any marked effect on the amount of formaldehyde bound. The use of unsealed containers for storage of the wheat immediately after treatment caused a reduction in the amount of formaldehyde bound. Pelleting of treated wheat stored for two weeks in sealed plastic bags did not result in losses of bound formaldehyde, but considerable losses occurred when the pelleted material was subsequently stored in hessian bags for a further ten weeks.
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ItemSome factors affecting efficiency of meat production from cattle( 1972)The main aim of the present work was to examine efficiency of production in beef cows. Efficiency of production is defined as the weight of calf produced divided by the feed consumed to produce that calf or those calves. This type of study takes a long time and, among other things, measurement of feed consumption is required. Neither in Australia nor overseas is there sufficient information of this type available for such study of beef cows. An alternative approach may be through "estimation" of cow feed intake from her weight by formulas in which the total requirement of feed is calculated from the maintenance requirements plus the requirement for production. It is generally accepted that both maintenance requirement and requirement of feed for production are proportional to a certain power of body weight. However, this procedure is of doubtful utility since several factors have been shown to affect maintenance requirement: lactation status (Neville and McCullough 1969), age (Brody 1945), level of nutrition (Lofgreen and Garret 1968), environmental conditions (Lambourn and Reardon 1963), parasites (Vercoe and O'Kelly 1972). There is also disagreement as to which power bodyweight must be raised in order to yield an appropriate value (Brody 1945; Kleiber 1961; Graham 1972). Furthermore, factors like appetite and individual variation are not considered in this type of approach. Because of the uncertainty of determining feed requirement from bodyweight data and of the difficulties in finding data directly pertaining to the question contained in the aim, I have studied various aspects of the major problem in the available beef cattle data. They are presented in Chapter II. To deal with the principal problem, I conducted an experiment with mice analagous to one required to study the problem directly with cattle. In this experiment feed intake was controlled. It was possible to examine in detail at some of the variables determining efficiency of production. The mice experiment is considered in Chapter III. In addition, I reviewed the literature in which factors like growth, longevity and fertility are considered as affecting efficiency of production. (Chapter I).