Selection for eye muscle depth breeding value increases dressing percentage in lambs
Gardner, G.E., Williams, A., Ball, A.J., Jacob, R.H. and Pethick, D.W. (2013) Selection for eye muscle depth breeding value increases dressing percentage in lambs. In: 64th Annual Meeting of the European Federation of Animal Science, 26 - 30 August, Nantes, France.
Pre-slaughter live weight taken directly off pasture and hot standard carcase weight data was collected from 7,849 lambs produced at 8 sites across Australia over a 4 year period (2007-2010) as part of the Sheep Cooperative Research Centre’s information nucleus flock experiment. These lambs were the progeny of 363 Terminal, Maternal, and Merino sires divergent for post-weaning eye muscle depth breeding values (PEMD). Dressing percentage was calculated by dividing hot standard carcase weight by pre-slaughter weight expressed as a percentage, and all three of these terms were analysed using a linear mixed effects models. The base model included fixed effects for site, year of birth, kill group, sex, birth-rear type, sire type and dam breed, with sire and darn identification included as random terms. Sire post-weaning fat depth, weight, and PEMD breeding values were included as covariates. The PEMD breeding value was found to have no effect on pre-slaughter weight, however it did increase (P<0.01) hot standard carcase weight by 1 kg across the 7 unit PEMD range. This increase was attributable to the impact of sire PEMD on dressing percentage which increased (P<0.01) by 1.7 dressing percentage units across the PEMD range. This represents a clear production advantage for producers using high PEMD sires, the progeny of which will have a similar live weight to low PEMD sires, but will deliver heavier carcase weights on the basis of their improved dressing percentage. Although live growth rate does not appear to be impacted, the implications for feed efficiency due to reduced fat deposition are currently being explored.
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|Murdoch Affiliation:||School of Veterinary and Life Sciences|
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