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Selection for lean growth in terminal sire sheep to produce leaner crossbred progeny

Published online by Cambridge University Press:  02 September 2010

R. M. Lewis ,
G. Simm ,
W. S. Dingwall  and
S. V. Murphy
R. M. Lewis
Affiliation:
Scottish Agricultural College, West Mains Road, Edinburgh EH9 3JG
G. Simm
Affiliation:
Scottish Agricultural College, West Mains Road, Edinburgh EH9 3JG
W. S. Dingwall
Affiliation:
Scottish Agricultural College, West Mains Road, Edinburgh EH9 3JG
S. V. Murphy
Affiliation:
Scottish Agricultural College, West Mains Road, Edinburgh EH9 3JG
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Abstract

A progeny test was designed to test whether genetic superiority for lean growth in terminal sires is expressed in their crossbred progeny when reared in a different environment. In each of 1986, 1987 and 1988, 22 Suffolk rams were chosen at the conclusion of an indoor, intensive performance testing regime on an index score that rated their propensity for lean growth, while constraining fat growth, at 150 days of age. Half of these rams had high index scores and half had low index scores. In each year, around 400 crossbred ewes were mated and the resulting lambs were finished on grass to one of three target live weights (35·5, 41·5, and 47·0 kg). Shoulder joints were dissected on 1505 lambs whilst half carcasses were dissected on 372 lambs. Double sampling techniques were then used to combine the data from the shoulder and half carcass more precisely to predict the lean, fat and bone weight and content in the carcass.

With each increment in target live weight, the carcasses were heavier and had proportionally more fat. The progeny of high index rams consistently had 144 (s.e.d. 32) g more lean, 66 (s.e.d. 12) g more bone, and 186 (s.e.d. 32) g less fat in a 19·7 (s.e. 0·5) kg carcass than progeny of low index rams, from the double sampling procedure. This improved composition reflected a correlated response to ram selection on the index. One standard deviation increase in ram index score corresponded to 51 g more lean and 64 g less fat in the 20 kg carcass of their crossbred offspring. These results show that the use of rams with high lean index scores in a crossbreeding system will produce lambs with leaner carcasses. Visual appraisals of fat and conformation both increased as the weight and, consequently, the fatness of the carcass increased. Offspring of high index rams were consistently scored as less fat than offspring of low index rams. But, at the lighter weights (35·5 and 41·5 kg), they were also scored lower in conformation — in effect, a penalty for their higher genetic merit for lean growth.

Keywords

carcass compositiongenetic parametersprogeny testingselectionsheep
Type
Research Article
Information
Animal Science , Volume 63 , Issue 1 , August 1996 , pp. 133 - 142
Copyright
Copyright © British Society of Animal Science 1996

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References

Bennett, G. L., Meyer, H. H. and Kirton, A. H. 1988. Effects of selection for divergent ultrasonic fat depth in rams on progeny fatness. Animal Production 47: 379–386.Google Scholar
Boldman, K. G., Kriese, L. A., Van Vleck, L. D., Van Tassell, C. P. and Kachman, S. D. 1995. A manual for use of MTDFREML. U.S. Department of Agriculture, Agriculture Research Service, Clay Centre, Nebraska.Google Scholar
Butterfield, R. M., Griffiths, D. A., Thompson, J. M., Zamora, J. and James, A. M. 1983. Changes in body composition relative to weight and maturity in large and small strains of Australian Merino rams. 1. Muscle, bone and fat. Animal Production 36: 29–37.Google Scholar
Cameron, N. D. 1992. Correlated responses in slaughter and carcass traits of crossbred progeny to selection for carcass lean content in sheep. Animal Production 54: 379–388.Google Scholar
Cameron, N. D. and Bracken, J. 1992. Selection for carcass lean content in a terminal sire breed of sheep. Animal Production 54: 367–377.Google Scholar
Cameron, N. D. and Curran, M. K. 1995. Responses in carcass composition to divergent selection for components of efficient lean growth rate in pigs. Animal Science 61: 347–359.Google Scholar
Conniffe, D. and Moran, M. A. 1972. Double sampling with regression in comparative studies of carcass composition. Biometrics 28: 1011–1023.CrossRefGoogle Scholar
Cook, G. L., Jones, D. W. and Kempster, A. J. 1983. A note on a simple criterion for choosing among sample joints for use in double sampling. Animal Production 36: 493–495.Google Scholar
Cuthbertson, A., Harrington, G. and Smith, R. J. 1972. Tissue separation — to assess beef and lamb variation. In Symposium on aspects of carcass evaluation. Proceedings British Society of Animal Production, pp. 113–122.Google Scholar
Genstat 5 Committee. 1993. Genstat 5 release 3 reference manual. Oxford University Press, Oxford.Google Scholar
Hammond, J. 1940. Farm animals, their breeding, growth inheritance. Edward Arnold and Co., London.Google Scholar
Hill, W. G. and Thompson, R. 1977. Design of experiments to estimate offspring-parent regressions using selected parents. Animal Production 24: 163–168.Google Scholar
Kempster, A. J. 1983. Carcass quality and measurement in sheep. In Sheep production (ed. Haresign, W.), pp. 59–74. Butterworths, London.Google Scholar
Kempster, A. J., Cook, G. L. and Grantley-Smith, M. 1986. National estimates of body composition of British cattle, sheep and pigs with special reference to trends in fatness. A review. Meat Science 17: 107–138.Google Scholar
McClelland, T. H., Bonaiti, B. and Taylor, St C. S. 1976. Breed differences in body composition of equally mature sheep. Animal Production 23: 281–293.Google Scholar
Meat and Livestock Commission. 1993. Sheep yearbook. MLC, Milton Keynes.Google Scholar
Patterson, H. D. and Thompson, R. 1971. Recovery of inter-block information when block sizes are unequal. Biometrica 58: 545–554.CrossRefGoogle Scholar
Simm, G. 1987. Carcass evaluation in sheep breeding programmes. In New techniques in sheep production (ed Marai, I. F. M. and Owen, J. B.), pp. 125–144. Butterworths, London.CrossRefGoogle Scholar
Simm, G. 1992. Selection for lean meat production in sheep. In Recent advances in sheep and goat research (ed. Speedy, A. W), pp. 193–215. CAB International.Google Scholar
Simm, G. and Dingwall, W. S. 1989. Selection indices for lean meat production in sheep. Livestock Production Science 21: 223–233.CrossRefGoogle Scholar
Simm, G., Young, M. J. and Beatson, P. R. 1987. An economic selection index for lean meat production in New Zealand sheep. Animal Production 45: 465–475.Google Scholar
Taylor, St C. S. 1985. Use of genetic size-scaling in evaluation of animal growth. Journal of Animal Science 61: suppl 2, 118–143.CrossRefGoogle Scholar
Thompson, J. M. 1990. Correlated response to selection for growth and leanness in sheep. Proceedings of thefourth world congress on genetics applied to livestock production, Edinburgh, 16: 266–274.Google Scholar
Thompson, J. M., Butterfield, R. M. and Perry, D. 1985. Food intake, growth and body composition in Australian Merino sheep selected for high and low weaning weight. 2. Chemical and dissectible body composition. Animal Production 40: 71–84.Google Scholar
Wolf, B. T. and Smith, C. 1983. Selection for carcass quality. In Sheep production (ed. Haresign, W.), pp. 493–514. Butterworths, London.Google Scholar
Woodward, J. and Wheelock, V. 1990. Consumer attitudes to fat in meat. In Reducingfat in meat animals (ed. Wood, J. D. and Fisher, A. V.), pp. 66–100. Elsevier, London.Google Scholar