The Genetic Effects Of Polymorphisms In 5’ Regulatory Region Of THRSP Gene On Main Meat Production Traits In Pigs

The meat production traits include daily gain, backfat thickness and loin muscle area in pig, and affected by many complicated factors. The genes related to fat deposition directly or indirectly influence the meat production traits by regulating the ways of carcass lipogenesis. THRSP is a transcription factor and activated by thyroid hormone receptor, and regarded as a major gene in the regulation of fat deposition. This study aimed to explore the genetic effect of THRSP gene polymorphism on pig meat production traits.924 pigs were selected from Landrace, Large White (LW), Duroc and White Duroc (WD), and fed under the same growing environment (raising condition). The average daily gain (ADG), average backfat thickness (ABF), eye muscle area (EMA), ABF/EMA×100 (meat-fat ratio, MFR) were measured. Five SNP sites and their genotyping were detected using sequencing in 5’ regulatory region of THRSP gene, then calculating the gene frequencies and analyzing the fixed effects and contribution rate of each genotype on the traits using least squares analysis model. The locus heritability of trait based on SNP site was employed for the estimate of the association of THRSP gene polymorphism with pig meat production traits. The results showed1. The results showed that five SNP sites, C-459T, T-400C, G-376A, G-98A and A-95T, were detected, which located at -459bp,-400bp,-376bp,-98bp and -95bp upstream of the start codon of pig THRSP gene, respectively.2. T-400C/G-376A combined site had higher fixed effects, in which the 400TT376GG genotype could decrease the ADG (-10.6938 g) and EMA (-2.9184 cm2), and increase MFR (2.2895). The contribution rates of 400TT376GG genotype were larger (P<0.01) on EMA (-8.80%) and EMA (7.49%), while the contribution rates of other genotypes no-significant based on a SNP site (P>0.05). Based on 5 SNP sites, the contribution rates of CCTTGGGGAA were larger (P<0.01) on the EMA (-7.61%) and EMA (6.44%).3. The locus heritabilities of MFR, EMA, ADG and ABF based on T-400C/G-376A were 0.2621,0.1918,0.0337 and 0.0086, respectively. The locus heritabilities of all traits based on other sites were less than 0.013. The results suggested that T-400C/G-376A of the THRSP gene may be associated with pig meat production traits, and regarded as major effect sites for MFR and EMA.