A COMPARISON BETWEEN 15 RAM BREEDS FOR EXPORT LAMB PRODUCTION .1. LIVEWEIGHTS, BODY COMPONENTS, CARCASS MEASUREMENTS, AND COMPOSITION

Results on the body and carcass composition of 7885 lambs sired by 371 rams of 15 different breeds mated to Romney cast-for-age ewes are giv en. Trials were run at the Ruakura Agricultural Centre and the Manutuk e Research Station from 1963 to 1972. Lambs of the different breeds we re slaughtered at the same average age so that differences between bre eds/crosses in liveweight and carcass weight reflected differences in growth rate. Ranked from heaviest to lightest mean age-adjusted carcas s weights, lambs sired by the Dorset Horn, Poll Dorset, Hampshire, Bor der Leicester, Suffolk, Dorset Down, South Suffolk, and South Dorset D own produced the heaviest carcasses, and those sired by the Cheviot, S outhdown, English Leicester, and Ryeland were intermediate. The Lincol n, Merino, and Romney sired carcasses were lighter. The longer-woolled Romney, Merino, and Lincoln had lowest dressing out percentages based on full liveweights and the short finer-wooled breeds such as the Sou thdown, Dorset Down, and Poll Dorset/Dorset Horn dressed 2-3% higher. When compared at the same carcass weight, lambs sired by the Southdown followed by the Ryeland had the fattest carcasses and those sired by the Suffolk, Cheviot, and Dorset Horn produced the least fat, leanest carcasses. The Southdown, Dorset Horn, South Dorset Down, and Poll Dor set crosses had the largest eye muscle areas for carcasses of similar weight.