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The effects of selection indices for sustainable hill sheep production on carcass composition and muscularity of lambs, measured using X-ray computed tomography

Published online by Cambridge University Press:  01 January 2008

N. R. Lambe ,
L. Bünger ,
S. C. Bishop ,
G. Simm  and
J. Conington
N. R. Lambe*
Affiliation:
Sustainable Livestock Systems Group, SAC, West Mains Road, Edinburgh EH9 3JG, UK
L. Bünger
Affiliation:
Sustainable Livestock Systems Group, SAC, West Mains Road, Edinburgh EH9 3JG, UK
S. C. Bishop
Affiliation:
Roslin Institute and Royal (Dick) School of Veterinary Studies, Roslin BioCentre, Midlothian EH25 9PS, UK
G. Simm
Affiliation:
Sustainable Livestock Systems Group, SAC, West Mains Road, Edinburgh EH9 3JG, UK
J. Conington
Affiliation:
Sustainable Livestock Systems Group, SAC, West Mains Road, Edinburgh EH9 3JG, UK
*
E-mail: [email protected]
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Abstract

A multi-trait selection index designed to improve the overall economic performance of hill sheep, including both maternal and lamb traits, has been developed and tested in a selection experiment over 7 years. Two versions of the index were tested, with different economic weights applied to the traits, on two different hill farms: one version including maternal and growth traits; the other version with additional breeding goals of carcass weight, fatness and conformation scores. Responses to selection, using both versions of the index, suggest that improvements are being made in overall index score and lamb growth. This study investigated the indirect effects of these selection indices on lamb carcass composition and muscularity traits, as measured using X-ray computed tomography (CT) scanning. A total of 499 lambs from the two hill farms were CT scanned at weaning (approximately 120 days of age). Approximately half of the lambs from each farm were from the selection line (S, animals with highest index scores selected for breeding), while the other half were from a control line (C, animals with average index scores selected). Composition and muscularity traits were estimated on each lamb from CT data and differences between genetic lines investigated, within farm, using restricted maximum likelihood analyses, adjusting for either live weight or age. Results showed that the selection index without carcass traits produced lambs with carcass composition that was not significantly different to control lambs at a given live weight or age. Including carcass traits in the index resulted in lambs with no compositional differences (except for a slight increase in bone) at a set age compared with controls. At a given live weight however, selection lambs had less fat and lower carcass weights and killing-out percentage. Muscularity (3-D muscle shape) and muscle area shape (2-D) were not improved as a result of selection on either version of the index (including carcass weight and grades in the breeding goals or not) and, at a fixed live weight, muscularity in hind leg and lumbar regions tended to be higher in the C line. To accelerate changes in carcass composition and muscularity within the context of a multi-trait selection index for hill sheep, consideration should therefore be given to including objective CT-derived carcass traits in the index in addition to the Meat and Livestock Commission (MLC) carcass grades or ultrasound measurements.

Keywords

body compositioncomputed tomographysheep
Type
Full Paper
Information
animal , Volume 2 , Issue 1 , January 2008 , pp. 27 - 35
Copyright
Copyright © The Animal Consortium 2008

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References

Anderson J (ed) 2003. Planned Carcase Production. Sheep Management Matters – a series on sheep management topics from the Meat and Livestock Commission. Meat and Livestock Commission, Milton Keynes, UK, no. 8, 1–16.Google Scholar
Conington, J, Bishop, SC, Grundy, B, Waterhouse, A, Simm, G 2001. Multi-trait selection indexes for sustainable UK hill sheep production. Animal Science 73, 413–423.CrossRefGoogle Scholar
Conington, J, Bishop, SC, Waterhouse, A, Simm, G 2004. A bio-economic approach to derive economic values for pasture-based sheep genetic improvement programmes: application to hill sheep farms in the UK. Journal of Animal Science 82, 1290–1304.CrossRefGoogle Scholar
Conington, J, Bishop, SC, Lambe, NR, Bünger, L, Simm, G 2006a. Testing selection indices for sustainable hill sheep production – lamb growth and carcass traits. Animal Science 82, 445–453.CrossRefGoogle Scholar
Conington J, Lambe NR, Bünger L, McLean KA, Bishop SC and Simm G, 2006b. Evaluation of responses to multi-trait selection indexes and genetic parameters for computer tomography-derived carcass traits in UK hill sheep. Proceedings of the Eighth World Congress on Genetics Applied to Livestock Production, Brazil, comm. no. 04-19.Google Scholar
De Boer, H, Dumont, BL, Pomeroy, RW, Weniger, JH 1974. Manual on EAAP reference methods for the assessment of carcass characteristics in cattle. Livestock Production Science 1, 151–164.Google Scholar
GenStat 8 Committee 2005. GenStat. Lawes Agricultural Trust. Rothamstead Experimental Station, Harpenden, UK.Google Scholar
Hopkins, DL, Safari, E, Thompson, JM, Smith, CR 2004. Video image analysis in the Australian meat industry – precision and accuracy of predicting lean meat yield in lamb carcasses. Meat Science 67, 269–274.Google Scholar
Jones, HE, Simm, G, Dingwall, WS, Lewis, RM 1999. Genetic relationships between visual and objective measures of carcass composition in crossbred lambs. Animal Science 69, 553–561.Google Scholar
Jones, HE, Lewis, RM, Young, MJ, Simm, G 2002a. Incorporating CT measures of composition and muscularity into selection programs for Suffolk sheep. Proceedings of the Seventh World Congress of Genetics Applied to Livestock Production 29, 461–464.Google Scholar
Jones, HE, Lewis, RM, Young, MJ, Wolf, BT 2002b. The use of X-ray computer tomography for measuring the muscularity of live sheep. Animal Science 75, 387–399.CrossRefGoogle Scholar
Jones, HE, Lewis, RM, Young, MJ, Simm, G 2004. Genetic parameters for carcass composition and muscularity in sheep measured by X-ray computer tomography, ultrasound and dissection. Livestock Production Science 90, 167–179.CrossRefGoogle Scholar
Jopson, NB, McEwan, JC, Dodds, KG, Young, MJ 1995. Economic benefits of including computed tomography measurements in sheep breeding programmes. Proceedings of the Association for the Advancement of Animal Breeding and Genetics 11, 194–197.Google Scholar
Jopson, NB, McEwan, JC, Fennessy, PF, Dodds, KG, Nicoll, GB, Wade, CM 1997. Economic benefit of including computed tomography measurements in a large terminal sire breeding programme. Proceedings of the Association for the Advancement of Animal Breeding and Genetics 12, 72–76.Google Scholar
Jopson, NB, Amer, P, McEwan, JC 2004. Comparison of two-stage selection breeding programmes for terminal sire sheep. Proceedings of the New Zealand Society of Animal Production 64, 212–216.Google Scholar
Lambe, NR, Conington, J, McLean, KA, Navajas, E, Fisher, AV, Bünger, L 2006. In-vivo prediction of internal fat weight in Scottish Blackface lambs, using computer tomography (CT). Zeitschrift Für Tierzüchtung Und Züchtungsbiologie – Journal of Animal Breeding and Genetics 123, 105–113.Google Scholar
Lambe, NR, Navajas, EA, McLean, KA, Simm, G, Bünger, L 2007. Changes in carcass traits during growth in lambs of two contrasting breeds, measured using computer tomography. Livestock Science 107, 37–52.Google Scholar
Laville, E, Bouix, J, Sayd, T, Bibe, B, Elsen, JM, Larzul, C, Eychenne, F, Marcq, F, Georges, M 2004. Effects of a quantitative trait locus for muscle hypertrophy from Belgian Texel sheep on carcass conformation and muscularity. Journal of Animal Science 82, 3128–3137.CrossRefGoogle ScholarPubMed
Lewis, RM, Macfarlane, JM, Simm, G, Emmans, GC 2004. Effects of food quality on growth and carcass composition in lambs of two breeds and their cross. Animal Science 78, 355–367.CrossRefGoogle Scholar
Macfarlane JM. 2006. Growth, development and carcass quality in meat sheep and the use of CT scanning as a tool for selection. PhD thesis, University of Edinburgh.Google Scholar
Navajas, EA, Glasbey, CA, McLean, KA, Fisher, AV, Charteris, AJL, Lambe, NR, Bünger, L, Simm, G 2006. In vivo measurements of muscle volume by automatic image analysis of spiral computed tomography scans. Animal Science 82, 545–553.CrossRefGoogle Scholar
Navajas, EA, Lambe, NR, McLean, KA, Glasbey, CA, Fisher, AV, Charteris, AJL, Bünger, L, Simm, G 2007. Accuracy of in vivo muscularity indices measured by Computed Tomography and association with carcass quality in lambs. Meat Science 75, 533–542.CrossRefGoogle ScholarPubMed
Purchas, RW, Wilkin, GH 1995. Characteristics of lamb carcasses of contrasting subjective muscularity. Meat Science 41, 357–368.Google Scholar
Purchas, RW, Davies, AS, Abdullah, AY 1991. An objective measure of muscularity: changes with animal growth and differences between genetic lines of Southdown sheep. Meat Science 30, 81–94.CrossRefGoogle ScholarPubMed
Rius Vilarrasa E, Bünger L, Matthews K, Maltin CA, Hinz A and Roehe R. 2007. Evaluation of Video Image Analysis (VIA) technology to predict meat yield of sheep carcasses online under abattoir conditions. Proceedings of the Annual BSAS Conference, Southport, UK, 2007, p. 108.Google Scholar
Stanford, K, Richmond, RJ, Jones, SDM, Robertson, WM, Price, MA, Gordon, AJ 1998. Video image analysis for on-line classification of lamb carcasses. Animal Science 67, 311–316.CrossRefGoogle Scholar
Waldron, DF, Clarke, JN, Rae, AL, Woods, EG 1992. Expected responses in carcass composition to selection for muscularity in sheep. Proceedings of the New Zealand Society of Animal Production 52, 29–31.Google Scholar
Wolf, BT, Smith, C, King, JWB, Nicholson, D 1981. Genetic parameters of growth and carcass composition in crossbred lambs. Animal Production 32, 1–7.Google Scholar
Wolf, BT, Jones, DA, Owen, MG 2006. In vivo prediction of carcass composition and muscularity in purebred Texel lambs. Meat Science 74, 416–423.CrossRefGoogle ScholarPubMed
Wood, JD, MacFie, HJH, Pomeroy, RW, Twinn, DJ 1980. Carcass composition in four sheep breeds: The importance of type of breed and stage of maturity. Animal Production 30, 135–152.Google Scholar
Wood, JD, MacFie, HJH, Brown, AJ 1983. Effects of body weight, breed and sex on killing-out percentage and non-carcass component weights in lambs. Meat Science 9, 89–99.CrossRefGoogle ScholarPubMed
Young, MJ, Nsoso, SJ, Logan, CM, Beatson, PR 1996. Prediction of carcass tissue weight in vivo using live weight, ultrasound or X-ray computed tomography measurements. Proceedings of the New Zealand Society of Animal Production 56, 205–211.Google Scholar
Young MJ, Simm G, Glasbey CA and Merrell B. 2002. Using CT scanning to improve carcass form in sheep. Proceedings of the Seventh World Congress of Genetics Applied to Livestock Production, Montpellier, France, comm. no. 02-06, p.18.Google Scholar