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A selection index for lean meat production in sheep

Published online by Cambridge University Press:  21 November 2017

G. Simm  and
W.S. Dingwall
G. Simm
Affiliation:
The Edinburgh School of Agriculture West Mains Road, Edinburgh EH9 3JG
W.S. Dingwall
Affiliation:
The Edinburgh School of Agriculture West Mains Road, Edinburgh EH9 3JG
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Extract

It is generally accepted that leanness of terminal sire sheep breeds should be increased. However, it is very difficult to define formally a selection goal for these breeds. Put loosely, at a given age, we probably require terminal sires with as much extra lean meat as possible, whilst minimising any increase in fat weight. In the past, selection has been mainly on weight for age, but this may actually increase fatness at the age of selection.

Intuitively we expect some in vivo measurements of carcass composition to help in achieving the selection goal. In practice, in vivo measurements of carcass composition in sheep are often imprecise, though the treatment of the animals can affect the relative precision. Ad libitum feeding on a high energy, high protein feed appears to increase the variation in carcass composition of ram lambs compared to those on a lower plane of nutrition (Simm et al, 1985 compared to Cuthbertson et al, 1983). Under these conditions we were able to predict carcass composition reasonably precisely from live weight and ultrasonic measurements (means and original and residual s.d.s for carcass lean weight: 18.30, 1.60 and l.00 kg and for fat weight 13.74, 2.70 and 0.96 kg).

Type
Ruminant Nutrition and Production
Information
Proceedings of the British Society of Animal Production (1972) , Volume 1987 , March 1987 , pp. 59
Copyright
Copyright © The British Society of Animal Production 1993

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References

Cuthbertson, A., Croston, D. and Jones, D.W. 1983. In vivo estimation of lamb carcass composition and lean tissue growth rate. In “In vivo estimation of body composition in meat animals”. Ed.Lister, D, C.E.C., pp. 163–166.Google Scholar
Simm, G., Avalos, E., Dingwall, W.S., King, J.W.B., Parratt, A.C., Owen, M.G. and Cuthbertson, A. 1985. Selection for improved lean meat production in Suffolk sheep: performance test regime and use of ultrasonics and X-ray computed tomography. Brit. Soc. Anim. Prod. Winter Mtg. 1985. Paper No. 35.Google Scholar
Simm, G., Young, M.J. and Beatson, P.R. 1987. An economic selection index for lean meat production in New Zealand sheep. Anim. Prod. (In press).Google Scholar