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Consumer preferences for lamb cuts are affected by the size, shape and fatness of cuts. Using computer tomography (CT), the best anatomical scan sites for prediction of weight and composition of four primal cuts; hindleg (HL), loin (LN), rack (RK) and forequarter (FQ) were examined. The economic benefit of incorporating cut distribution into a breeding programme was evaluated. The weight and composition of cuts were predicted by CT in 300 lambs. Each CT image was classified according to anatomical location relative to the spine, and the areas of subcutaneous fat, intermuscular fat, lean and bone measured for each cut. A stepwise regression procedure was used to find the best subset of two anatomical positions to predict the tissue depot weights and total cut weight for each cut. The results show that the weight and composition of primal lamb cuts can be very accurately predicted from six to eight CT scan sites recorded per animal ( R 2 range from 0.85 to 0.98 for total cut weights). Net benefit predicted from two selection indices for a hypothetical breeding programme given a 10-year horizon showed higher (NZ$1.02 million) net benefits when selection was for composition of cuts and fat (six images) than breeding for weight of lean and against fat in the carcass (four images). |
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