Abstract:
Proc. Aust. Soc. Anim. Prod. (1978) 12: 238 GROWTH RATE EFFECTS ON THE ALIMENTARY TRACT AND ASSOCIATED FAT OF SHEEP O. SLEZACEK* and D.M. MURRAY** In contrast available of the associated fat of understanding of to information on carcass composition, little data are effect of growth rate on the alimentary tract and sheep. Such data are desirable for a more complete growth rate effects on whole body composition. Fat-trimmed weights and chemical composition of alimentary tract parts and the weight of gut fat were determined in a recent growth experiment. The experiment studied the effects of growing 27 castrate male progeny of Border Leicester x Merino ewes and Dorset Horn rams from a live weight of 15 to 40 kg on either ad libitum feed intake (H), wrestricted intake (L) or ad libitum feed intake to 25 kg followed by a SO-day period of weight s&is which, in turn, was followed by - libitum ad feeding (HMH). Nine animals in each treatment`were fed a pelleted mixture of lucerne (80%) and cereal grain (20%) and killed at 25, 30, 35 and 40 kg. Results for the weights of the separate parts of the alimentary tract in the three treatments are shown in Table 1. TABLE 1: The effect of growth rate (kg/day) on the weight (g) of the separate parts of the alimentary tract and gut fat of sheep. The restricted growth of the L animals caused a reduction in the weights of the omasum and the intestines compared to those in the other treatments. These changes in the gut of the L animals, however, had no apparent detrimental effect on their ability to digest, absorb and store nutrients as carcass composition was similar in all three treatments (Murray and Slezacek 1976). The data in Table 1 also show that an intermittent period of weight stasis in the HMH treatment had no significant effect on the weights of the separate parts of the gut. The chemical composition of the separate parts of the gut was similar in all three treatments despite treatment effects on the weights of some parts. Pooled values (%'s) across treatments for water, protein and ether extract, respectively, were:- rumen-reticulum and omasum 78.2, 15.1 and 6.2; abomasum - 72.6, 11.5 and 16.0; small intestine 76.9, 16.2 and 6.9; *large intestine - 75.4, 15.6 and 8.9. MURRAY, D.M. and SLEZACEK, 0. (1976). J. agric. Sci. Camb. 87: - 171, * Hawkesbury Agricultural College, Richmond, N.S.W., 2753. ** School of Wool and Pastoral Sciences, University of New South Wales, Kensington, N.S.W., 2033. 238.