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UBC Theses and Dissertations

Growth - with particular reference to it's assessment in beef cattle production Williams, Charles Melville


This thesis is the study of the literature pertinent to the assessment of growth in addition to the analysis of growth data obtained from the Albino Rat, Yorkshire Swine, Black-Tail Deer and a group, of ten Hereford Bulls. It has been concluded that animals grow at a constant percentage rate relative to body weight over each distinct portion of their growth curve. A significant error in the expression of rate of gain is introduced if animals growth rate is calculated over any but an instantaneous period. The latter is possible because growth of an animal body is directly proportional to the protoplasmic mass, a first order reaction and as such is exponential and when the expression is integrated, the slope of the' regression line, logarithm of body weight on time is provided over the period when relative growth rate is constant. From the results of ration variations with male Wistar rats it was concluded that upon returning to ad libitum feeding they will grow at the same relative rate as their controls despite thirty per cent reduction below ad libitum intake over periods up to two thirds of the birth to sexual maturity phase. The extrapolation is made that beef bull calves proceeding from varying environments normally, experienced on pure-breeding establishments will not provide biased data when placed on a test ration and allowed a period for the rumen microflora to become adjusted to the new ration.

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