Abstract

Dressing percentage (DO%), the dressed carcass expressed as a portion of live weight, is markedly influenced by the particular definition used. Farmers usually want to estimate cold (works) carcass weights (CCW) from live weights taken on lambs recently removed from pasture (FLW). Gut fill plays a major role in DO%. As lambs empty out after removal from pasture, DO% increases until this effect is offset by loss of carcass and organ weights from increasing periods of starvation. Data on 2207 weaned and shorn lambs ranging from 10 to 46 kg FLW and slaughtered over 3 seasons could be described by the regression: CCW (kg) = 0.473 FLW (kg) - 1.92, RSD = 0.67 kg, r=0.95. DO% calculated from this regression for lambs slaughtered close to the New Zealand mean CCW of 13 kg averaged 41% and increased as FLW increased. Shorn lambs of similar weight sired by longwool breeds had lower DO% than lambs sired by Down breeds. Lamb DO% dropped following weaning. Lambs with carcasses in the leaner A and Y grades dressed lower than lambs in the fatter pre 1983-84 P grade when compared at the same live weight, illustrating that DO% increases as lambs get fatter.

AR, Bray

Proceedings of the New Zealand Society of Animal Production, Volume 44, , 223-226, 1984