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The consequences of index selection on carcass composition in Suffolk sheep

Published online by Cambridge University Press:  20 November 2017

R. M. Lewis
Affiliation:
Animal Biology Division, SAC, King's Buildings, Edinburgh EH9 3JG, UK
G. C. Emmans
Affiliation:
Animal Biology Division, SAC, King's Buildings, Edinburgh EH9 3JG, UK
G. Simm
Affiliation:
Animal Biology Division, SAC, King's Buildings, Edinburgh EH9 3JG, UK
W. S. Dingwall
Affiliation:
Animal Biology Division, SAC, King's Buildings, Edinburgh EH9 3JG, UK
J. FitzSimons
Affiliation:
Animal Biology Division, SAC, King's Buildings, Edinburgh EH9 3JG, UK
J.C. Fraser
Affiliation:
Animal Biology Division, SAC, King's Buildings, Edinburgh EH9 3JG, UK
J.E. Donbavand
Affiliation:
Animal Biology Division, SAC, King's Buildings, Edinburgh EH9 3JG, UK
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Extract

Early in the 1980s a selection index was designed at SAC to improve the rate of lean growth in terminal sire sheep which combined ultrasound measurements of fat and muscle depth, and live weight at 150 days of age (Simm and Dingwall, 1989). Beginning in 1985, this index was applied in the SAC Suffolk flock in a performance test. In 1994, rams from a line selected on this index weighed on average 12% more (8 kg) and had 12% lower fat depth (– 0.9 mm) and 10% higher muscle depth (2.9 mm) than rams from an unselected Control line. Comparison of Selection and Control line animals has thus far been based on live predictors of carcass composition at weights substantially heavier than typical market lamb weights. The aims of this study were to test whether selection decisions based on the lean growth index produced an improvement in actual carcass composition in purebred terminal sire sheep and whether these changes persisted at live weights different from those under which selection was carried out.

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Copyright
Copyright © The British Society of Animal Science 1999

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References

Genstat 5 Committee. 1993. Genstat 5 Release 3 Reference Manual. Oxford University Press, Oxford.Google Scholar
Simm, G. and Dingwall, W. S. 1989. Selection indices for lean meat production in sheep. Livestock Production Science 21:223233.CrossRefGoogle Scholar