Association Of The POUIFI And CAST Gene Polymorphisms With Rabbit Carcass Traits

POU1F1 (also named PIT-1) is the first pituitary-specific transcription factor and CalpastatinC CAST) is also an endogenous inhibitor that controls the activity of calpains. Both of them are associated with carcass quality. Many researchers considered the two genes as the candidate marker for growth. But there is a little research about rabbit meat. The purpose of this research was to investigate the effect of the POU1F1 and CAST gene on meat quality traits in the Hyla, Champagne, Tianfu Black rabbit breeds using PCR-sequencing. We got the results as the following:(1) For CAST gene in rabbit, we detected one single nucleotide polymorphism located at 271 bp in intron 5 and three genotypes (GG, TT and GT). The genotype frequency of TT was far hiGHer than GG and GT. The T allele frequency (0.6240 to 0.7163) was also much hiGHer than G which showed a hiGH prevalence in these breeds. Chi-square tests showed that genotypic frequencies were not in Hardy-Weinberg equilibrium (P<0.05) in any of the three rabbit populations. The three rabbit populations had intermediate levels of genetic diversity according to PIC. The results of the association showed that rabbits with the GT genotype had a significantly greater pHoh and b*oh than those with the TT genotype. Similarly, rabbits with the GT genotype had a significantly greater pHoh and b*oh than those than TT rabbits for the biceps femoris muscle(P<0.05). In addition, GT rabbits had significantly hiGHer pH24h than rabbits with the GG genotype for the biceps femoris muscle. Rabbits with the GT genotype had a significantly lower intramuscular fat content in the longissimus dorsi and biceps femoris muscles than those with genotype TT and GG. The value of intramuscular fat was significantly hiGHer in rabbits with the TT genotype in longissimus dorsi.(2) For POU1F1 gene in rabbit, we detected one single nucleotide polymorphism located at 536 bp in intron 5 and three genotypes (CC, TT and CT). The genotype frequency of CC was hiGHer than TT and CT. The C allele frequency (0.5604 to 0.6806) was also much hiGHer than T which showed a hiGH prevalence in these breeds. Chi-square tests showed that genotypic frequencies were not in Hardy-Weinberg equilibrium (P<0.05) in any of the three rabbit populations. The three rabbit populations had intermediate levels of genetic diversity according to PIC. There were non-significant differences among POU1FI genotypes CC, TT, and CT were found for pH (Oh,24h), L* (Oh,24h), a* (Oh,24h), and b* (Oh,24h) in the rabbit longissimus dorsi muscle (P>0.05). Rabbits with the CC genotype had a significantly greater pHoh in the rabbit biceps femoris muscle (P<0.05) than rabbits with the CT genotype. Least squares means for cooking loss from CT and CC rabbits were significantly YnGHer than the one from TT rabbits (P<0.05). Rabbits with the CC genotype had a significantly hiGHer intramuscular fat content in the longissimus dorsi than those with genotype TT and CT (P<0.05), whereas the CC and TT genotypes had similar intramuscular fat in the biceps femoris and both of them had hiGHer intramuscular fat in this muscle than the CT genotype.(3) The single nucleotide polymorphism of POU1F1 gene was significantly related to pH in the biceps femoris and intramuscular fat both in longissimus dorsi and biceps femoris. There were no significant differences in the association between the SNP of CAST and the meat traits but the single nucleotide polymorphism obviously affected the meat corlorness.(4) Three hundred and seventy-two meat rabbits from three breeds were slaughtered and also determined the meat quality trait indicators. The results showed that no difference of live weight before slaughter and carcass weight were observed among three breeds. We also determined the pH value, meat colour and fat percentage of longissmus dorsi and the right hind leg muscle of three breeds. The results indicated that the pH value of longissmus dorsi from Tianfu black rabbit was greater (P< 0.01) that that of Champagne rabbit. Meanwhile, the meat colour and fat percentage showed a similar trend between longissmus dorsi and the right hind leg muscle, and the difference among different breeds was obvious.