Abstract

Two experiments investigated relationships between biochemical measurements and carcass fat in lambs. In the first, artificially reared Dorset lambs, weaned at 5 (early) or 13 (late) weeks were slaughtered at 5, 9 and 13 weeks for carcass fat determination. In the second experiment, 330 Coopworth male lambs (entire and castrate), were weaned at 9 weeks of age and slaughtered at 21 weeks. At 9 and 13 weeks of age early weaned lambs which had lower carcass weights had significantly lower glucose and insulin levels, and less internal and carcass fat than milk fed lambs. In the second experiment a similar carcass weights entire lambs were leaner than castrates and had lower blood glucose. In contrast to results in the first experiment, lambs grown to slaughter under a uniform dietary regime in the second showed a negative correlation between insulin and fat measurements. It is suggested that insulin is an important regulator of fat deposition in the milk fed lamb but its exact role in the ruminant lamb remains unclear.

RG, Keogh

Proceedings of the New Zealand Society of Animal Production, Volume 44, , 189-192, 1984