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 given. Trials were run at the Ruakura Agricultural Centre and the Manutuke Research Station from 1963 to 1972. Lambs of the different breeds were slaughtered at the same average age so that differences between breeds/crosses in liveweight and carcass weight reflected differences in growth rate. Ranked from heaviest to lightest mean age-adjusted carcass weights, lambs sired by the Dorset Horn, Poll Dorset, Hampshire, Border Leicester, Suffolk, Dorset Down, South Suffolk, and South Dorset Down produced the heaviest carcasses, and those sired by the Cheviot, Southdown, English Leicester, and Ryeland were intermediate. The Lincoln, Merino, and Romney sired carcasses were lighter. The longer-woolled Romney, Merino, and Lincoln had lowest dressingout percentages based on full liveweights and the short finer-wooled breeds such as the Southdown, 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
A94091Received 26 September 1994; accepted 27 April 1995 1 Deceased sired by the Suffolk, Cheviot, and Dorset Horn produced the least fat, leanest carcasses. The Southdown, Dorset Horn, South Dorset Down, and Poll Dorset crosses had the largest eye muscle areas for carcasses of similar weight.
