GH gene polymorphisms and expression associated with egg laying in muscovy ducks (Cairina moschata)

Accumulated evidence suggests that the growth hormone (GH) gene plays a physiological role in the control of reproductive function. Here, we examined the correlation between egg-laying traits and GH gene polymorphisms and expression patterns in the muscovy duck (Cairina moschata). PCR single-strand conformation polymorphism was used to identify polymorphisms in intron 3 of GH. One single nucleotide polymorphism (g.3270 A > G) was detected by sequencing, and the frequencies of the A and G alleles in the population were 0.65 and 0.35, respectively. A comparison test showed that the AA genotype group had more consecutive laying days and more eggs at 300 days than the GG genotype group (P < 0.05); however, there was no significant difference for the age at first laying (P > 0.05). Such a significant correlation between GH polymorphisms and egg-laying performance suggested that GH could be a candidate locus affecting the laying trait in muscovy duck. Furthermore, real-time fluorescent quantitative PCR demonstrated that GH is expressed in all selected tissues, but is highly expressed in the hypothalamic-pituitary-gonadal axis and heart. This unique expression pattern suggested that GH may exert its local physiological function through the autocrine or paracrine pathway during gonad development and growth in the muscovy duck. The data presented in this paper revealed GH polymorphisms and expression patterns in the muscovy duck and indicated a potential regulatory effect of GH on reproduction.