School of Agriculture, Food and Ecosystem Sciences - Theses

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End date: 1979 × Subject: Feeding and feeds × Author: Barbiero, Sergio A ×

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    Some factors affecting efficiency of meat production from cattle
    Barbiero, Sergio A ( 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).