Pasture type in relation to live-weight gain, carcass composition, iodine nutrition and some rumen characteristics of sheep II. Carcass composition and the non-carcass components of live weight

Abstract

1. The results of two trials with Romney ewes grazed on perennial rye-grass (P), perennial rye-grass with white clover (P + C), short-rotation rye-grass (S) and short-rotation rye-grass with white clover (S + C) are reported. Chemical and dissection analyses of their carcasses were made and the weights of certain internal organs were obtained.2. It was found that the sheep grazed on the P plots had the lightest carcasses (56·2 and 40·9 lb. in trials I and II, respectively), followed by those on the P + C (70·2 and 59·2 lb.), by those on S (74·7 and 61·2 lb.) and the heaviest carcasses were yielded by sheep from the S + C plots (81·5 and 69·1 lb., respectively).3. The weights of dissectible fatty tissue and chemical fat of the carcasses were related to the carcass weights of the different groups of sheep; the group with the lightest carcass weight had the least fat. The other components of the carcass (protein, water and ash) followed the order for group mean carcass weights except that the S carcasses in trial II had slightly less water, protein and ash than the P + C carcasses. The percentage chemical fat of the S carcasses in trial I was also lower than the P + C carcasses.4. In general, the non-carcass components of live weight (head, feet, skin, liver, mesenteric fat, omental fat, kidneys, stomach empty, and intestines empty) all followed the same pattern of increasing weight (P < P + C < S < S + C).