Hostname: page-component-586b7cd67f-rcrh6 Total loading time: 0 Render date: 2024-11-22T23:15:20.121Z Has data issue: false hasContentIssue false
  • English
  • Français

Relationships between lamb carcass quality traits measured by X-ray computed tomography and current UK hill sheep breeding goals

Published online by Cambridge University Press:  01 January 2008

N. R. Lambe ,
J. Conington ,
S. C. Bishop ,
K. A. McLean ,
L. Bünger ,
A. McLaren  and
G. Simm
N. R. Lambe*
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
S. C. Bishop
Affiliation:
Roslin Institute (Edinburgh), Roslin, Midlothian EH25 9PS, UK
K. A. McLean
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
A. McLaren
Affiliation:
Sustainable Livestock Systems Group, SAC, West Mains Road, Edinburgh EH9 3JG, UK
G. Simm
Affiliation:
Sustainable Livestock Systems Group, SAC, West Mains Road, Edinburgh EH9 3JG, UK
*
E-mail: [email protected]
Get access

Abstract

Genetic parameters were estimated between current UK hill sheep breeding goals and lamb carcass composition and muscularity traits derived using X-ray computed tomography (CT). To produce these estimates, a total of 648 lambs from two hill farms were CT scanned at weaning (ca 120 days of age), over 3 years, and total weights of carcass muscle (MUSC), fat (CFAT) and bone (BONE) and internal fat (IFAT) were predicted. Previously derived muscularity indices were also calculated for the hind leg (HLMI) and lumbar (LRMI) regions, to assess muscle shape. Data for current breeding goals (lamb performance and maternal traits) were also included from a total of 10 297 lamb records and 12 704 ewe records. Heritabilities were estimated for each trait and genetic and phenotypic correlations were calculated between each CT trait and other lamb or ewe traits. Moderate to high positive genetic correlations were found between CT-predicted tissue weights and breeding goals, which were also weights (lamb weaning weight, carcass weight, mature ewe weight, average weight of lambs reared by the ewe). CFAT was positively genetically correlated with ultrasound backfat depth at weaning (UFD) and subjective fatness grade at slaughter (MLCF), suggesting that carcass fat could be decreased using selection on any of these predictors. Ultrasound muscle depth at weaning (UMD) and subjective conformation score at slaughter (MLCC) had high genetic correlations with the muscularity indices (HLMI and LRMI), but correlations with MUSC were not significantly different from zero. This implies that selection to improve MLCC is likely to be increasing the ‘roundness’ of muscle shape in the high-priced carcass region, but having little impact on total lean meat yield. Correlations of CT traits with the other ewe traits (number of lambs weaned, number of lambs lost, longevity, fleece weight) were generally small or not significantly different from zero. The genetic parameters generated in this study can now be used in selection index calculations to assess the benefits of including lamb CT traits in future selection programmes for hill sheep.

Keywords

body compositioncarcass compositioncomputed tomographygenetic parameterssheep
Type
Full Paper
Information
animal , Volume 2 , Issue 1 , January 2008 , pp. 36 - 43
Copyright
Copyright © The Animal Consortium 2008

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Anderson, J 2003. Planned carcase production. Sheep Management Matters 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, Belo Horizonte, Brazil, 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.CrossRefGoogle Scholar
Gilmour, AR, Cullis, BR, Welham, SJ, Thompson, R 2001. ASREML Reference Manual. NSW Agriculture, Orange, NSW, Australia.Google Scholar
Jefferies, BC 1961. Body condition scoring and its use in management. Tasmanian Journal of Agriculture 32, 19–21.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.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
Karamichou, E, Richardson, RI, Nute, GR, McLean, KA, Bishop, SC 2006. Genetic analyses of carcass composition, as assessed by X-ray computer tomography, and meat quality traits in Scottish Blackface sheep. Animal Science 82, 151–162.CrossRefGoogle Scholar
Kvame, T, Vangen, O 2007. Selection for lean weight based on ultrasound and CT in a meat line of sheep. Livestock Science 106, 232–242.CrossRefGoogle Scholar
Lambe, NR, Brotherstone, S, Young, MJ, Conington, J, Simm, G 2005. Genetic relationships between seasonal tissue levels in Scottish Blackface ewes and lamb growth traits. Animal Science 81, 11–21.CrossRefGoogle 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). Journal of Animal Breeding and Genetics 123, 105–113.CrossRefGoogle Scholar
Lambe NR, Bünger L, Bishop SC and Conington J 2008. The effects of selection indices for sustainable hill sheep production on carcass composition and muscularity of lambs, measured using X-ray computed tomography. Animal 2, 27–35.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
McEwan, JC, Morris, CA, Fennessy, PF, Greer, GJ, Bain, WE, Hickey, SM 2001. Selection for high or low backfat depth in Coopworth sheep: breeding ewe traits. Animal Science 73, 241–252.CrossRefGoogle 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
Nsoso, SJ, Young, MJ, Beatson, PR 2004. Genetic and phenotypic parameters and responses in index component traits for breeds of sheep selected for lean tissue growth. Small Ruminant Research 51, 201–208.CrossRefGoogle 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
Wolf, BT, Smith, C 1982. Selection for carcass quality. In Proceedings of the 35th Nottingham Easter School (ed. W Haresign), pp. 493–514. Butterworth, London.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