Relationship between genetic variants of POU1F1, PROP1, IGFBP3 genes and milk performance in Guanzhong dairy goats

• Genotype D2D2 at POU1F1-DdeI locus, genotype TC at POU1F1-AluI locus and genotype X2X2 at IGFBP3-XspI locus were found for the first time in Guanzhong dairy goats.
• The POU1F1-AluI polymorphism was significantly associated with milk performance in Guanzhong dairy goats.
• Genotype TT of the POU1F1-AluI locus was suggested to be an effective DNA marker for senior milk fat content or acidity in dairy goats.

The aim of this study was to determine and verify if the potential genetic variations in the POU1F1, PROP1 and IGFBP3 genes could be related to dairy goat milk performance. This study detected the polymorphisms of POU1F1-PstI, POU1F1-DdeI, POU1F1-AluI, PROP1-Hin6I and IGFBP3-XspI loci, and evaluated their associations with milk performance in Guanzhong dairy goats. The present results confirmed the previous genotypes and found three unreported genotypes in Guanzhong dairy goats (e.g. genotype D2D2 at POU1F1-DdeI locus, genotype TC at POU1F1-AluI locus, genotype X2X2 at IGFBP3-XspI locus, respectively). The genotypic frequencies of all analyzed loci were at Hardy-Weinberg equilibrium (P > 0.05) except POU1F1-PstI locus (P < 0.01). The PIC values of POU1F1-PstI locus and IGFBP3-XspI locus were 0.328 and 0.329, respectively, suggesting that these two loci possessed median polymorphism. Association analysis demonstrated no significant relationship between the POU1F1-PstI, POU1F1-DdeI, PROP1-Hin6I and IGFBP3-XspI loci and milk performance in Guanzhong dairy goats (P > 0.05). Interestingly, in the POU1F1-AluI locus, this SNP was significantly associated with a total of six milk traits (P < 0.05). Moreover, the individuals with genotype TT possessed superior morning milk fat content, afternoon milk fat content and average milk fat when compared with those of genotype TC (P = 0.026, P = 0.029, P = 0.036, respectively); Consistently, genotype TT had higher morning milk acidity, afternoon milk acidity and average milk acidity than genotype TC (P = 0.028, P = 0.027, P = 0.038, respectively). These findings suggested that the POU1F1-AluI locus had significantly effect on milk performance, and genotype TT could become an effective DNA marker for senior milk fat content or acidity, which could benefit to dairy goat selection and breeding through marker-assisted selection (MAS).