Abstract
A genome-wide association study (GWAS) was performed on the intramuscular fat percentage in pork chops in commercially available swine in Canada. The Duroc, Iberian, Lacombe, Berkshire, and Pietrain breeds were crossed with Large White sows, and their F1 offspring were ranked according to the intramuscular fat percentage (IMF %) obtained in their longissimus dorsi (LD) muscle loin chops. The ideal IMF % is considered to be >3%, whereas the average is ~1.5% in North American pork. The genetics of the top 10% and bottom 10% from our sample population were analysed by using 80,000 single nucleotide polymorphism (SNP) microarrays in the GWAS. Our sample population had an average IMF % of 2.5 ± 0.7%, but some pork achieved >7% IMF. GWAS analysis revealed SNP markers which were associated with the highest marbled pork chops on chromosomes 5, 7, and 16. Using the Sus scrofa/ susScr 11.1 map, we determined that the nearest genes were sarcospan (SSPN), Rh-associated glycoprotein (RHAG), and EGF-like fibronectin and laminin G (EGFLAM), which can be linked with muscular dystrophy disorders. We tested a subpopulation of Duroc-sired animals and found a different set of markers close to glycine receptor beta (GRLB) and potassium channel 3 (KCNJ3) on chromosomes 8 and 15. Based on our results, we could achieve pork with a good IMF of >4% from animals commercially bred and raised to standard market weights of 110 kg. The choice of obtaining a good marbling line of pigs is not necessarily breed-specific, but it is line-specific.
Highlights
A genome-wide association study (GWAS) was performed on commercial boars and sows and their offspring to find the quantitative trait loci (QTLs) that best matched up with the degree of intramuscular fat percentage (IMF %) found in the longissimus dorsi (LD) muscle at the time of slaughter
A GWAS analysis was performed on the intramuscular fat percentage (IMF %) of the longissimus dorsi muscle in pigs
There are many claims of superior marbling in various genetic lines, but these claims must be backed up with verifiable genetic tests that can be performed by a third party
Summary
A genome-wide association study (GWAS) was performed on commercial boars and sows and their offspring to find the quantitative trait loci (QTLs) that best matched up with the degree of intramuscular fat percentage (IMF %) found in the longissimus dorsi (LD) muscle at the time of slaughter. Is called marbling, and is associated with better palatability of the cooked pork chops. Marbling or IMF % is the fat in the muscle fibres of loin pork chops that gives flavour, texture, moisture, and some tenderness to the cooked meat. Most pork produced in Canada contains on average 1.5% IMF in lean longissimus muscle. Low IMF % pork has problems with a lack of taste, moisture, and tenderness. The beef industry has set their minimal amount of marbling fat at 7% IMF in a fresh loin steak [5] to attain a premium grade of AAA or prime
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