Identifying the marbling genes in Western Canadian Commercial Hogs
Banff Pork Seminars 2018.
Plain language summary
Commercial boars were used to breed offspring for pork production. Their first generation offspring F1 were grown to market weight and the loins were assessed for the degree of marbling fat ~intramuscular fat % in their pork chops. Breeds of Duroc, Iberian and Lacombe were used in the comparison. The Duroc was the best for marbling but it was not consistent. The gene were compared between the boars using DNA microarray analysis and found different genes in different breeds and different animals of the same breed. The Canadian market typically has IMF% values of 1.5%. We found certain boars can produce offspring that have 7% IMF which is close to a properly marbling cut of AAA beef.
Marbling is the fat in the muscle of loin pork chop that gives flavour, texture, and moisture and some tenderness to the cooked meat. It is visually assessed as small white fat and can be objectively scored as the intramuscular fat %. At Lacombe, we have scored the loin muscle by NMR to assess the IMF % in > 600 commercial western Canadian pigs. Using whole genome analysis on Illumina 80,000 SNP microarrays with Delta Genomics and Golden Helix software, we have started to identify the genes associated with contributing to IMF %. Duroc, Iberian, and Lacombe boars, crossed with Large White sows, were segregated according to the IMF % values in their F1 offspring. The highest level of IMF % was obtained from the Duroc sires and was linked to genetic markers on chromosomes 4, 8, and 1. Lacombe markers were on chromosomes 16, 17, 9 and 4. Iberian IMF % biomarkers were on 2 and 15.
Implications: The locations of genetic biomarkers of IMF % are unique to different breeds. In Canadian Duroc commercial boars, we are finding a QTL region located on chromosome 4 at QTL ASGA0018089 , which is near the LRRC6 gene which is a general transcriptional factor.