Polymorphism Of RBP4 And RARG Genes And Their Association Analysis With Reproductive Traits In Songliao Black Pig

The reproductive traits of sows are critical to the productive and economic benefits of the pig farming industry.In recent years,candidate genes and molecular markers related to reproductive traits have captured much attention.In this study,the single nucleotide polymorphism(SNP)of RBP4 and RARG gene in 132 Songliao black pigs are screened by PCR-HRM combined with DNA sequencing.The correlation between SNPs and reproductive traits is analyzed with the aim to find SNPs related with the reproductive traits of Songliao black pigs,which lays the foundation for the breeding of high-performance strains.The findings are shown as follows:1.Two SNPs,namely G45 A and C170 T,were detected in the RBP4 gene,which are located in exon 3 and exon 5 respectively.Three genotypes(GG,GA and AA)are found at the G45 A locus,and two genotypes(CC and CT)are found at the C170 T locus.No SNP is explored in both exon 6 and exon 8 of RARG gene.2.The distribution of G45 A in the Songliao black pigs is even and uniform,and its genetic variation and genetic polymorphism are of medium level.The distribution of C170 T in the Songliao black pigs is uneven,and its genetic variation and genetic polymorphism are low.The latter conforms with Hardy-Weinberg law(P<0.05),while the former does not(P>0.05).3.In the G45 A locus,the total number born and number born alive are shown as GG>GA>AA in the three genotypes.GG genotype has significantly higher total born and number born alive than AA genotype(P<0.05).GG genotype has significantly lower 3-week weight than GA genotype(P<0.05).GG genotype has significantly lower weaning weight than GA and AA genotypes(P<0.05).Different genotypes do not show significant differences on birth weight and number of nipples(P>0.05).There is no significant difference in 3 groups on birth weight and number of nipples(P>0.05).In the C170 T locus,there was no significant differences between CC and CT genotypes in terms of all traits(P>0.05).4.In conclusion,the G45 A locus of RBP4 gene has a great influence upon the litter size of Songliao black pigs,and it can be used as a reference for selecting high-yielding pigs.However,whether G45 A locus can be used as a genetic marker related to the litter size or not is to be studied and explored further.The C170 T locus may not be a mutation locus associated with reproductive traits in Songliao black pigs.In the follow-up study,the population of pigs should be increased to further verify.It is unclear whether the RBP4 gene is the major gene affecting the reproductive traits of Songliao black pigs,and it needs to be verified in terms of its function and mechanism.