Polymorphisms of three neuroendocrine-correlated genes associated with growth and reproductive traits in the chicken

The identification and utilization of potential candidate genes for QTL with significant effects on economically important traits are becoming increasingly important in poultry breeding programs. Chicken insulin-like growth factor binding protein 1 and 3 and signal transducers and activators of transcription 5B (STAT5B) genes are 3 essential nodes for signaling pathways and gene networks of growth and reproduction. The pooled DNA sequencing approach was used for identification of 9 SNP of the 5' upstream region of the 3 genes. A total of 826 individuals from Beijing You chicken were genotyped for 5 SNP using a modified PCR-RFLP method and the association with chicken growth and reproductive traits was studied using the GLM procedure. The T56039403C (T-808C) SNP of the insulin-like growth factor binding protein 1 gene was associated with BW at 10 wk of age (P = 0.0061), and the C56072547T (C-968T) SNP of the insulin-like growth factor binding protein 3 gene was associated with BW at 8 and 10 wk of age (P = 0.0056 and P = 0.0016, respectively). The C4535156T (C-1591T), G4533815A (G-250A), and G4533675C (G-110C) SNP of the STAT5B gene were associated with age at first egg (P = 0.0143, P = 0.0088, and P = 0.0114, respectively). Moreover, Lewontin's D' (|D'|) and r(2) of C4535156T and G4533815A SNP, C4535156T and G4533675C SNP, and G4533815A and G4533675C SNP of the STAT5B gene were 0.939 and 0.852, 0.967 and 0.858, and 0.971 and 0.896, respectively. The 3 SNP were strong-linked with each other and lay within a haplotype block. Our results suggest that these SNP were significantly associated with early growth or with sexual maturation in chickens, or both, and may be potential molecular markers for MAS.