Effects of intergenic single nucleotide polymorphisms in the fast myosin heavy chain cluster on muscle fiber characteristics and meat quality in Berkshire pigs

The heterogeneity of myosin heavy chain (MyHC) isoforms is closely related to muscle fiber characteristics, and meat quality in pigs. The fast MyHC gene cluster on porcine chromosome 12 contains MYH2, MYH1, and MYH4, which encode three fast MyHC isoforms expressed in adult skeletal muscle. Here, we identified four intergenic single nucleotide polymorphisms (SNPs) in the gene cluster. Of these, SNP1 and SNP2, which were located near MYH2, were genotyped in 199 Berkshire pigs. SNP1 were significantly associated with the total fiber number (P = 0.046) and intramuscular fat contents (P = 0.041), and SNP2 had significant effects on type I fiber number/area compositions (P = 0.039 and P = 0.041, respectively), water holding capacity (drip loss, P = 0.045; cooking loss, P = 0.001), and meat color (P = 0.003). Taken together, our results suggest that the intergenic SNPs near MYH2 can affect muscle fiber formation and meat quality by modifying the regulatory elements of this gene cluster in pigs.