Study On The Polymorphisms Of CAPN1 Gene And Their Relationships With Meat Quality Traits In Yak

The associations of single nucleotide polymorphisms (SNPs) of Calpain 1 (CAPN1) gene with meat quality attributes of M. longissimus dorsi from Gannan yaks (Bos grunniens, n=181)were studied. Yaks were harvested at 2,3,and 4 yr of age (n=51,59, and 71,respectively), and samples of each yak carcass were aged at 4℃for 0,1,3,7,14 or 21d.The meat quality attributes (shear force, dry cooking loss (DCL), moist cooking loss (MCL), pressing loss (PL) and pH) from all 181 animals with six postmortem aging days each were determined, while the chemical composition (moisture, protein and fat) was only determined from 60 yaks (20 individuals per age at harvest) with six aging days each. Fragments of the yak CAPN1 gene were amplified using four pairs of primers and subjected to Single Strand Conformational Polymorphism and sequencing analyses. The results showed as follows:1.The results showed that the four loci all had SNPs through PCR-SSCP technique. The sequencing result showed that 3F loucs had a base transformation of G/A in intron 12.The allelic frequency of A was 0.6989, and the genotype frequency of AA was 0.4751 and AA was dominant genotype.4F loucs had a base transformation of G/A in intron 13.The genotype frequencies of BB and AB were 0.3923 and 0.3978. 5F loucs had a base transformation of G/T in intron9. The genotype AA was dominant genotype and the genotype frequency of AA was 0.8287.6F loucs had a base transformation of A/G in exonl4, and caused the 411 of asparagine (N)→aspartate (D).The change was the missense mutation.2.Genetic analysis showed that the polymorphism information contents (PIC) of 3F and 4F were 0.3323,0.3665, respectively. Both of them were in the moderate polymorphism. The polymorphism information contents (PIC) of 5F and 6F were 0.1520,0.1807, respectively. Both of them were in the low polymorphism. The population of yak was Hardy-Weinberg equilibrium at the 3F,5F,6F, beside 4F.3.Interaction of 3F genotype x aging days was evident (P<0.05) for fat percentage. Genotype had little effect (P>0.05) on fat percentage at 0,3,7,14 and 21 days of aging averaged over age at harvest. However, genotype BB had greater fat percentage compared to yaks with genotype AA and AB at 1 day of aging averaged over age at harvest (P<0.05).4. Results showed that 4F affected (P<0.001) pressing loss. Genotype AA had lesser pressing loss compared to yaks with genotype AB and BB averaged over age at harvest and aging days (P<0.05).Interactions of genotype x age at harvest were evident (P<0.10) for protein and fat percentage. Genotype had little effect (P>0.05) on protein and fat percentage for 2-and 4-yr-old yaks averaged over aging time. In 3-yr-old yak, genotype AA had greater fat percentage compared to yaks with genotype AB and BB averaged over aging time (P<0.05).Interaction of genotype x aging days was evident (P<0.05) for moist cooking loss. Genotype had little effect (P>0.05) on moist cooking loss at 0,1,3 and 21 days of aging averaged over age at harvest. Genotype AA had lesser moist cooking loss than yaks with genotype AB (P <0.05) at 7 days of aging averaged over age at harvest, but not BB.However, Genotype AB had lesser moist cooking loss than yaks with genotype BB (P<0.05) at 14 days of aging averaged over age at harvest, but not AA.5.Genotype AA had lesser shear force compared to genotype AB (P<0.05) averaged over age at harvest and aging days. Averaged over age at harvest and aging days there was a trend (P<0.10) for fat percentage to be greater in genotype AB compared to AA. But still had interactions of 5F genotype x aging days, and 5F genotype x age at harvest x aging days for shear force.6. Results showed that 6F affected (P<0.05) protein percentage, genotype AA had greater protein percentage compared to yaks with genotype AB (P<0.05). Interaction of genotype x age at harvest was evident (P<0.05) for moist cooking loss. Genotype had little effect (P>0.05) on moist cooking loss for 2-and 4-yr-old yaks averaged over aging time. In 3-yr-old yak, genotype AB had lesser moist cooking loss compared to yaks with genotype AA (P<0.05) averaged over aging time.