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Intramuscular fat is reduced in lambs from sires selected for leanness

Pannier, L., Gardner, G.E., Geesink, G.H., Ball, A.J., Jacob, R.H. and Pethick, D.W. (2011) Intramuscular fat is reduced in lambs from sires selected for leanness. In: 57th International Conference of Meat Science and Technology, 7 - 12 August, Ghent, Belgium pp. 1355-1358.

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Abstract

The Australian lamb industry selects for lean meat yield through the use of Australian Sheep Breeding Values, however there is concern regarding the impact of this on eating quality, as selection for lean growth has been linked with declining intramuscular fat (IMF) levels. Sires with reduced subcutaneous fat depth breeding values (PFAT) have reduced carcass fatness and increased loin muscle weight, whereas those with higher post-weaning eye muscle depth breeding values (PEMD) have increased muscularity. We hypothesised that selection for reduced PFAT and increased PEMD will decrease IMF levels. IMF was measured on 5556 lamb loins and linear mixed effects models were used to analyse this data. Fixed effects included site, drop, sex, birth type-rear type, dam breed and sire breed within sire type, sire type and kill group within site by drop, with sire and dam by drop identification as random terms. Hot carcass weight (HCWT), PFAT and PEMD were used as covariates to assess their association with IMF. HCWT (P<0.05) increased IMF levels by 2.40 IMF% units across the 28kg HCWT range. Reducing PFAT below 1.25 mm PFAT, decreased IMF by 0.61 IMF% units over the PFAT range. PEMD demonstrated a weaker association with IMF, reducing IMF levels by 0.44 IMF% units. Current selection objectives with high PEMD sires to increase lean meat yield would not impact as strongly on IMF levels as sires with low PFAT, however continuous selection for leanness might need to slow down to avoid IMF levels to drop below the consumer acceptable levels.

Publication Type: Conference Paper
Murdoch Affiliation: School of Veterinary and Biomedical Sciences
URI: http://researchrepository.murdoch.edu.au/id/eprint/20276
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