Factors associated with differences in carcass conformation in lamb

Abstract

Factors associated with differences in carcass conformation were studied in three experiments involving 85 pairs of lambs, half of which had been selected as having blocky conformation and half leggy conformation. Pairs of carcasses were matched for carcass weight and age at slaughter. The blocky carcasses contained more fat and less red meat and bone than the leggy carcasses. They also had a higher proportion of the fatter cuts (loin, ribs, and flap) and a lower proportion of the leaner cuts such as the leg. A taste panel found the palatability characteristics of leg meat from both types of carcasses acceptable and did not differentiate between them. The differences in conformation strongly influenced the export grading of the carcasses, the blocky carcasses grading predominantly Prime Down Cross and the leggy carcasses mainly Prime Crossbred and Y. Southdown sires produced the blockiest carcasses and the other breeds studied produced the leggiest carcasses. Within-breed variation was also noted in one experiment where conformation differences were less extreme. The leggy carcasses came from animals that had heavier liveweights at slaughter than the blocky animals, although the hot carcass weights of both were the same. The results are discussed in relation to the New Zealand meat industry. The conclusion is reached that the blocky carcasses have no superiority in terms of meat content or proportion of high-priced cuts, and that in future more emphasis should be placed on economic characteristics and less on conformation in breeding and crossbreeding programmes.