Bishop, S. C.

Bünger, L.

Conington, J.

Lambe, N. R.

McLaren, A.

McLean, K. A.

Simm, Geoff

English

Lambe, NR

Conington, JE

Bishop, SC

McLean, KA

Bunger, L

McLaren, A

Simm, G

SRUC - Scotland's Rural College

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

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 littleimpact 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

Edinburgh Research Explorer

Accuracy of in vivo muscularity indices measured by Computed Tomography and association with carcass quality in lambs.

An objective measure of muscularity: changes with animal growth and differences between genetic lines of Southdown sheep.

Body condition scoring and its use in management.

Genetic analyses of carcass composition, as assessed by X-ray computer tomography, and meat quality traits in Scottish Blackface sheep.

Genetic and phenotypic parameters and responses in index component traits for breeds of sheep selected for lean tissue growth.

Genetic parameters for carcass composition and muscularity in sheep measured by X-ray computer tomography, ultrasound and dissection.

Genetic parameters of growth and carcass composition in crossbred lambs.

Genetic relationships between seasonal tissue levels in Scottish Blackface ewes and lamb growth traits.

Genetic relationships between visual and objective measures of carcass composition in crossbred lambs.

Growth, development and carcass quality in meat sheep and the use of CT scanning as a tool for selection.

In vivo measurements of muscle volume by automatic image analysis of spiral computed tomography scans.

In-vivo prediction of internal fat weight in Scottish Blackface lambs, using computer tomography (CT).

Selection for carcass quality.

Selection for high or low backfat depth in Coopworth sheep: breeding ewe traits.

Selection for lean weight based on ultrasound and CT in a meat line of sheep.

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