Sheep carcasses and their appraisal. 1. Characteristics of commercial Australian lamb and mutton

Abstract

Lamb and mutton carcases from abattoirs, and from wholesale and retail outlets, were studied to provide information on the characteristics of typical commercial Australian sheep carcases. Characteristics examined were the weight, length (pubic symphysis to first rib), subcutaneous fat depth (13th rib) and fleshing index (shape) of intact carcases, fat depths on the loin, shoulder and chump cuts, weights and proportions of wholesale lamb cuts, before and after trimming of excess fat, and Warner-Bratzler shear measures of tenderness for lamb and mutton. Lamb carcases studied varied considerably in weight, shape and fatness, with fat depth measurements of up to 30 mm being recorded on some chump cuts. The proportion of trimmed major cuts of lamb varied from 61.3 to 75.7% of cold carcase weight. Because of the large variability in fatness and the considerable variation in trimmed cut proportions, we consider that appraisal systems for lamb should aim to discriminate between carcases on these bases. Variation in eating quality of lamb may offer less ground for discriminating between carcases, as shear values for lamb were observed to be small. Shear values for medial M. longissirnus cores were generally greater than those for lateral cores in both lamb and mutton, though differences were significant (P < 0.05) only for lamb. Mutton carcases were more variable in their characteristics and yielded meat with greater shear values (P < 0.05) than lamb. However in many cases, shear values for mutton samples were also quite small. It was reasoned that potential could exist for greater utilization of two- and possibly also four-tooth animals as sources of table meat.