Skip to main content Accessibility help
×
Home

The effects of selection for lean growth in Suffolk sires on the saleable meat yield of their crossbred progeny

  • G. Simm (a1) and S. V. Murphy (a1)

Abstract

This experiment involved a commercial evaluation of carcasses of extensively reared crossbred lambs. These were sired by Suffolk rams from either a selection line or a control line of a Scottish Agricultural College (SAC) selection experiment, in which selection wasfor lean growth, or by Suffolk ‘reference sires’ from an industry co-operative breeding scheme (SSRS). The lambs were slaughtered at a target live weight of 42 kg between June and October 1992. In total, 421 lamb carcasses were included in the evaluation, 173 from six selection-line rams, 193 from six control-line rams and 55from three SSRS rams. Each of the carcasses was visually appraised for estimated subcutaneous fat proportion and for conformation of the shoulder, loin and leg, as well as being classified using conventional Meat and Livestock Commission (MLC) scales for fat and conformation. Animals were slaughtered at an average age of 139·5 (s.d. 25·6) days and achieved an average cold carcass weight of 20·04 (s.d. 0·96) kg. Carcasses had an average estimated subcutaneous fat proportion of 122·3 (s.d. 22·4) g/kg — equivalent to MLC fat class 3L to 3H. Overall conformation scores, on a 15-point scale, averaged 8·63 (s.d. 1·80) points. Carcasses were cut into joints according to a leading supermarket specification. The weights of pairs of shoulder, flank, loin and leg joints were obtained for each carcass, as well as weights of bone and fat removed during jointing. Saleable meat weights and proportions averaged 15·31 (s.d. 0·76) kg and 765·9 (s.d. 10·0) g/kg respectively. At a constant carcass weight, the SAC selection-line progeny were significantly younger (-11 days), had a significantly higher carcass value (+£1·50), a significantly lower estimated subcutaneous fat proportion (-13 g/kg), and a significantly higher weight of saleable meat (+0·1 kg) and higher proportion ofsaleable meat (+4 glkg) than control-line progeny, but had lower conformation scores. SSRS progeny had similar growth and fatness to selection-line lambs, but had poorer conformation, and significantly more bone in the carcass than either of the SAC lines. When comparisons were made at a constant estimated subcutaneous fat proportion, all differences in conformation between SAC lines disappeared. However, SSRS progeny remained poorer in conformation. The SSRS rams werefrom afoundation generation of the scheme, and were not expected to be markedly superior for carcass characteristics. Carcass weight was byfar the most important predictor of weight of saleable meat, or leg and loin joint weights. Conformation and estimated fat proportion made only marginal improvements, if any, to the precision of prediction, with fat proportion being the more important of the two predictors.

Copyright

References

Hide All
Bass, J. J., Carter, W. D., Woods, E. G. and Moore, R. W. 1984. Evaluation of the ability of two carcass conformation systems to predict carcass composition of sheep Journal of Agricultural Science, Cambridge 103: 421427.
Bruwer, G. G., Naude, R. T. and Vosloo, W. A: 1987. An evaluation of the lamb and mutton carcass grading system in the Republic of South Africa. 3. Fatness score, conformation score and carcass mass as predictors of carcass composition. South African Journal of Animal Science 17: 9093.
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: 379388.
Cameron, N. D. and Bracken, J. 1992. Selection for carcass lean content in a terminal sire breed of sheep Animal Production 54: 367377.
Croston, D., Kempster, A. J., Guy, D. R. and Jones, D. W. 1987. Carcass composition of crossbred lambs by ten sire creeds compared at the same carcass subcutaneous fat proportion Animal Production 44: 99106.
GENSTAT 5 Committee. 1993. GLNSTAT 5 release and reference manual. Clarendon Press, Oxford.
Guy, D. R. and Croston, D. 1994. UK experience and progress with sheep sire referencing schemes. Proceedings of the fifth world congress on genetics applied to livestock production, vol. 18, pp. 5558.
Horgan, G. W., Murphy, S. V. and Simm, G. 1995. Automatic issessment of sheep carcasse s by image analysis Animal Science 60: 197202.
Kempster, A. J. 1983. Carcass quality and its measurement in sheep. In Sheep production (ed. Haresign, W.), pp. 5974. Butterworths, London.
Kempster, A. J., Croston, D. and Jones, D. W. 1981. Value of conformation as an indicator of sheep carcass composition within and between breeds Animal Production 33: 3949.
Kempster, A. J., Cook, G. L. and Grantley-Smith, M. 1986. National estimates of the body composition of British cattle, sheep and pigs with special reference to trends in fatness. A review. Meat Science 17: 107138.
Lewis, R. M., Simm, G., Dingwall, W. S. and Murphy, S. V. 1996. Selection for lean growth in terminal sires to produce eaner crossbred progeny. Animal Science In press.
McClelland, T. H., Bonaiti, B. and Taylor, St C. S. 1976. Breed differences in body composition of equally mature sheep. Animal Production 23: 281293.
Meat and Livestock Commission. 1993. Sheep yearbook. MLC, Milton Keynes.
Patterson, H. D. and Thompson, R. 1971. Recovery of inter-block information when block sizes are unequal Biometrika 58: 545554.
Purchas, R. W., Davies, A. S. and Abdullah, A. Y. 1991. An objective measure of muscularity: changes with animal growt h and differences between genetic lines of Southdown sheep. Meat Science 30: 8194.
Schrooten, C. and Visscher, A. H. 1987. [Genetic parameters of growth and carcass quality in Texel Sheep.] Rapport, Instituut voor Veetcltkundig Onderzoek ‘Schoonoord’, no. B283.
Shrestha, J. N. B., Fortin, A. and Heaney, D. P. 1986. Genetic and phenotypic parameters of carcass traits in ram lambs reared artificially in a controlled environment Canadian Journal of Animal Science 66: 905914.
Simm, G. 1987. Carcass evaluation in sheep breeding programmes. In New techniques in sheep production (ed. Marai, I. F. M. and Owens, J. B.), pp. 125144. Butterworths, London.
Simm, G. 1992. Selection for lean meat production in sheep. In Recent advances in sheep and goat research (ed. Speedy, A. W.), pp. 193215. C.A.B. International, Wallingford.
Simm, G. 1994. Developments in improvement of meat sheep. Proceedings of the fifth world congress on genetics applied to livestock production, vol. 18, pp. 310.
Simm, G. and Dingwall, W. S. 1989. Selection indices for lean meat production in sheep Livestock Production Science 21: 223233.
Wolf, B. T., Smith, C., King, J. W. B. and Nicholson, D. 1981. Genetic parameters of growth and carcass composition in crossbred lambs Animal Production 32: 17.
Wolf, B. T., Smith, C. and Sales, D. I. 1980. Growth and carcass composition in the crossbred progeny of six terminal sire breeds of sheep Animal Production 31: 307313.
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. 66100. Elsevier, London.
Young, M. J. 1990. Developmental changes in muscularity and selection to alter body composition. Proceedings of the eighth conference of the Australian Association of Animal Breeding and Genetics, pp. 553554.

Keywords

Related content

Powered by UNSILO

The effects of selection for lean growth in Suffolk sires on the saleable meat yield of their crossbred progeny

  • G. Simm (a1) and S. V. Murphy (a1)

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed.