Breed and sex differences among equally mature sheep and goats 6. Breed correlations for body composition and food conversion efficiency

Abstract

ABSTRACTBreed means are given for 40 traits relating to food conversion efficiency and body composition at the same stage of maturity in seven breeds of sheep and a feral goat breed. In terms of breed means, food intake and food conversion efficiency were genetically correlated, as were most traits associated with fatness or leanness.Highly inter-correlated measures of breed fatness were proportion of fat in the carcass, proportion of total carcass fat found in the rib plus loin, the fat : muscle ratio and the lipid concentration in the dry matter of all tissues except bone. Dressing proportion was highly correlated with all these measures of fatness.Breeds with a high proportion of subcutaneous fat did not necessarily have a low proportion of intra-abdominal fat. A low proportion of carcass fat in the rib plus loin was associated with a high proportion in the shoulder (inter-breed correlation —0·7): both were measures of leanness. Muscle : bone ratio was not correlated with fatness or leanness. Slower maturing, larger breeds had slightly more bone, less fat and more lean in their higher-priced cuts. Breeds with heavier fleeces were fatter (0·7). The food conversion efficiency of a breed was largely independent of its body composition.