Abstract：Reproductive performance and litter size are important economic traits for sheep (Ovis aries), and luteinizing hormone/choriogonadotropin receptor (LHCGR) has an important impact on sheep reproductive performance and litter size. To verify the effect of LHCGR gene on litter size in sheep, this study used Dorper sheep, Small Tail Han sheep and Tan sheep and their hybrid offspring (D, TH, F1, F2 and H1) 5 sheep populations as research subjects. Flight mass spectrometry (Sequenom MassARRAY® SNP) technology was used to genotype the 4 mutation sites of LHCGR gene: g.75709226 G>T, g.75733123 G>A, g.75747421 A>C and g.75748150 A>G. The association analysis of litter size was performed. The results showed that, the g.75709226 G>T and g.75733123 G>A loci were low polymorphism (polymorphic information content, PIC<0.25) in 5 sheep populations, and the g.75747421 A>C and g.75748150 A>G loci were moderate polymorphism (0.25≤PIC<0.5) in 5 sheep populations. In the g.75747421 A>C site, the number of litter size in wild-type AA individuals in H1 sheep population was significantly higher than that in heterozygous AC and mutant CC individuals (P<0.05); there was no significant difference in litter size among the genotypes of g. 75709226 G>T, g.75733123 G>A and g.75748150 A>G sites (P>0.05). There was complete linkage disequilibrium between g.75747421 A>C and g.75748150 A>G loci, resulting in 4 haplotypes and 6 diplotypes; the litter size of the diplotype H3H3 individuals was significantly higher than that of the diplotype combination H1H1, H1H2, H1H3 and H2H2 individuals (P<0.05), and there was no significant difference with the diplotype combination H2H3 individuals (P>0.05). The results of this study showed that, the polymorphism of LHCGR gene g.75747421 A>C locus was associated with the lambing number of H1 sheep population, and this locus could be used as a molecular genetic marker to improve lambing traits of H1 sheep population; the AAAA diplotypes in LHCGR gene SNP sites g.75747421 A>C and g.75748150 A>G could be used as potential molecular markers for screening lambing traits in sheep. This study provides an important reference for LHCGR gene selection in sheep lambing number traits, and provides a theoretical basis for sheep breeding work.
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