Association Of μ-CAPN Gene Polymorphism With Meat Traits In Nanyang Cattle

μ-CAPN, also named Ca²⁺-dependent protease, is a specifically calcium- activated neutral cysteine thiol endopeptidase and is ubiquitously consisted in animals. Ca²-activated protease is main factor that causes to degrade muscle fibre, also is the main factor that leads to degrade muscle fibre in the muscle-aging process at post- mortem. It directly determines tenderization level of muscle.Theμ-CAPN gene was chosen as a candidate gene to study meat performance traits in 70 NanYang cattles. Sequencing and PCR-SSCP were applied to analyze the relationship between polymorphisms of 6 loci inμ-CAPN gene 5'-UTR, exon 9, 14 and intron 1, 14, 21, and combined genotype of exon 9 and intron 21 in NanYang cattles with the meat performance traits for the purpose of providing molecular maker information to facilitate the breeding efficiency of preferable meat quality. The results as follows:1. 5'-UTR, exon14(CAPN530), intron 1(CAPN5331), 14(CAPN4751) loci ofμ-CAPN gene were cloned and analysed by PCR-SSCP in NanYang cattle. No poly- morphisms were detected in these loci.2. Lower polymorphsm was observed and equilibrium of Hardy-Weinberg was detected by analysis of chi-square in CAPN316 locus ofμ-CAPN. The allele freque- ncy of G and C were 93% and 7% respectively. The genotype frequency of GG, GC and CC were 87%, 11% and 2% respectively. Significant correlation was observed between the locus and pH at 6h at post-mortem by comparison of meat quality. But no correlation was observed between the locus and drip losses, cooking losses, IMF, Shear force and Diameter of muscle fibre. It was detected that genetype GG yielded more tender beef than GC did, genetype and tenderness exhibited significant correlation(p<0.05).3.μ-CAPN gene CAPN4753 showed low polymorphism by analysis of chi-square, and was disequilibrium of Hardy-Weinberg. The allelic frequencies of A and C were 8% and 92% respectly. The genotype frequencies of AA, AC and CC were 3%, 13% and 84% respectively. Significant correlation was observed between the locus and Shear force at d 1 at post-mortem by comparison of meat quality. But no correlation was observed between the locus and pH, drip losses, cooking losses, IMF and Diameter of muscle fibre. It was detected that genetype GG yielded more tender beef than GC did, exhibited very significant correlation(p<0.01).4. Significant correlation was observed in combined genotype that genetype CAGG yielded beef with 4.2% more tenderness than CCGC did at Shear force; genetype CAGG yielded beef with 2.6% more tenderness than CCGG did at Shear force, but they didn't exihibited significant correlation; and neither did those between CCGC ,CCGG and Shear force.