The body composition of growing sheep during milk feeding, and the effect on composition of weaning at various body weights

Abstract

Thirty-four (13 <J, 21 $) entire cross-bred lambs were suckled on reconstituted, spray-dried cows' milk from 2 days of age for varying periods of time up to 18 weeks before being weaned on to solid food or slaughtered to determine chemical composition. The body composition of each sheep (water, fat, protein, energy) was also estimated from the tritiated water (TOH) space at 3-weekly intervals during milk feeding, at intervals of 5-8 weeks subsequently and at slaughter. Comparison between. TOH estimates and whole body analysis confirmed the accuracy of the previously-derived prediction equations.The relationship between each of the various body components and body weight for individual sheep during milk feeding was described by a 'bent' (non-rectangular) hyperbola. There were no substantial differences between animals in either the position or slope of the lower asymptote nor in the slope of the upper asymptote. There were, however, substantial differences in the point of intersection of the two asymptotes both within and between sexes. The mean intersection points for males and females were 17-7 and 14-4 kg body weight respectively.Sheep weaned at body weights of 11-16 kg subsequently followed the previously defined pattern of growth. Weaning at higher body weights (21-34 kg, body fat not less than 5-5 kg) resulted initially in both fat and/or body weight loss. In the final fattening phase of growth early-and late-weaned sheep of the same sex had similar body composition but females were fatter than males.on body composition were also studied. In vivo estimates of body composition were obtamed in In a previous experiment (Searle, Graham & individual animals throughout the growing period O'Callaghan, 1972) the course of growth in sheep by means of the tritiated water (TOH) technique was described in terms of the relationship between of Searle (1970a). the various body components (fat, protein, water In the mathematical treatment of the results of and energy) and body weight. A model was set up the previous experiment ) each in which four phases of growth were distinguished, phase was represented by a linear equation, implynamely the milk-feeding phase, the period of rumen ing a sharp transition from one phase to the next, development and a prefattening followed by a though it was recognized that smooth transitions fattening ruminant phase. The lambs in that were more likely. The results of the current experiexperiment were on milk exclusively for only 3 ment were analysed by a modification of the weeks (body weight ca. 9 kg) before being intro-previously used piecewise linear regression model, duced to solid feed. Further work has now been allowing for smooth transition between phases. An carried out to examine the course of growth with essential feature of the mathematical treatment of more extended milk-feeding (up to 18 weeks and the results in both experiments was the use of data body weights of 41 kg). The effect of weaning and from individual sheep rather than the pooled data subsequent growth as well as t...

Changes in cell number and size and in lipogenic enzyme activity in adipose tissues during growth and fattening of Lacha (Manech) lambs

“…In this study, development of adipose tissues, expressed both in absolute terms and relative to empty LW, was greater between 24 and 36 kg LW than between 12 2 and 24 kg. This is consistent with the observation that adipose tissue is the tissue which develops the latest and its allometric coefficient is between 1.3 and 1.6 (Hammond, 1932;Fourie et al, 1970;Kirton et al, 1972; Kempster, 1980 (Searle and Griffiths, 1976 (1985) founding that in kids the largest relative weight lost after weaning among the depots studied omental, mesenteric, perirenal and pericardic was observed in the perirenal depot.…”

Influence of weaning age, management, and slaughter age on export lamb carcass production and slipe wool weights

“…Although previous work has shown similar changes in composition (Mitchell & Jagusch 1972;Penning & Treacher 1975;Searle & Griffiths 1976), it has also been suggested that early nutritional effects on composition tend to be less pronounced at live weights above 40 kg. The results show that extreme weaning-age treatments markedly affected growth performance, but at the same time achieved differences in carcass composition over the 30-50 kg liveweight range.…”

Body composition of animals during sucking and the immediate post-weaning period

“…given milk-substitutes varying in crude protein (nitrogen x 6.25) content from 120 to 460 g/kg, while Searle and colleagues studied the changes in the body composition of lambs whilst with their mothers at pasture, or when given a cow's-milk diet and weaned under pen conditions (Searle, 1970;Searle et al 1972;Searle & Griffiths, 1976). These authors are agreed that when lambs are restricted to a particular diet, such as reconstituted cow's milk, their body composition is closely related to body-weight rather than to age or rate of gain, an observation which is in agreement with the conclusions of Mitchell et al (1928).…”