An independent validation association study of carcass quality, shear force, intramuscular fat percentage and omega-3 polyunsaturated fatty acid content with gene markers in Australian lamb.

Previous association studies revealed several single nucleotide polymorphisms (SNPs) that explained the observed phenotypic variation for meat tenderness and long-chain omega-3 polyunsaturated fatty acid (PUFA) content of Australian lamb. To confirm the validity of these associated SNPs at predicting meat tenderness and omega-3 PUFA content, an independent validation study was designed. The OvineSNP50 genotypes of these animals were used to impute the 192 SNP Meat Quality Research (MQR) panel genotypes on nearly 6200 animals from the Cooperative Research Centre for Sheep Industry Innovation Information Nucleus Flock and Sheep Genomics Falkiner Memorial Field Station flock. Association analysis revealed numerous SNP from the 192 SNP MQR panel that were associated with carcass quality - fat depth at the C-site and eye muscle depth; shear force at day 1 and day 5 after slaughter (SF1 and SF5); and omega-3 PUFA content at P<0.01. However, 1 SNP was independently validated for SF5 (i.e. CAST_101781475). The magnitude of the effect of each significant SNP and the relative allele frequencies across Merino-, Maternal- and Terminal-sired progeny was determined. The independently validated SNP for SF5 and the associated SNP with omega-3 PUFA content will accelerate efforts to improve these phenotypic traits in Australian lamb.

Sources of variation of health claimable long chain omega-3 fatty acids in meat from Australian lamb slaughtered at similar weights.

The sources of variation of health claimable omega-3 polyunsaturated fatty acids (eicosapentaenoic acid, EPA+docosahexaenoic acid, DHA) in 2000 Australian lambs were investigated using 98 sires (Merino, maternal or terminal breeds) that were mated to about 5000 Merino or crossbred (Border Leicester×Merino) ewes. Pasture was supplemented with feedlot pellets, grains or hay as necessary, when the availability of quality green pasture was limited. Lambs were grown at 8 sites across Australia and when slaughtered the longissimus lumborum muscle was collected. Site and kills within sites were the major sources of variation for health claimable fatty acids. These environmental effects are likely to be driven by dietary background. The sire variance differed from about one twentieth to a half of the residual lamb within dam variation, depending on site and kill. This is the first comprehensive study to investigate on-farm sources of variation of long chain omega-3 polyunsaturated fatty acid content of lamb meat.