Abstract
The aim of this study was to identify variations of vasoactive intestinal peptide (VIP) and VIP receptor-1 (VIPR-1) genes that might be associated with turkey reproductive traits. One hundred twenty turkey hens were recorded for age at first egg (AFE), first egg weight (FEW), egg number (EN), total egg weight (TEW), laying period (LP), and broodiness. The DNA was isolated from blood samples and subjected to PCR amplification of the meleagrine VIP and VIPR-1 genes. The SNPs were detected by single-strand conformation polymorphism and the variant DNA fragments were sequenced. One mutation in 3’-UTR of VIP (G5846A) and two SNPs in intron 2 of VIPR-1 (C17687T and A17690T) were found, all of them novel. The associations of the three detected SNPs with the reproductive traits of turkeys were evaluated. The detected polymorphisms were used for marker-trait association analyses. The results of association analysis showed that G5846A on 3’ UTR of VIP has a significant association with LP, EN, TEW, and AFE. The G allele of G5846A was the favourable SNP allele for LP, EN, and TEW traits. The AA genotype of A17690T on intron 2 of VIPR-1 was significantly associated with higher LP, EN, and TEW. AGAA haplotype showed association with higher EN and TEW. These results suggest that the SNPs in 3’-UTR of VIP and intron 2 of VIPR-1 genes may influence egg production traits in turkey hens.Keywords: broodiness, candidate gene, egg production, single nucleotide polymorphism, VIPR-1
Highlights
Reproduction traits have been of primary interest to breeders in the poultry industry
The hens that showed broodiness behaviour after a few layings were recorded as broody hens
A substitution of G with A was detected in VIPe6 at position 5846 bp (G5846A), which occurred in 3’-UTR region of the vasoactive intestinal peptide (VIP) gene
Summary
Reproduction traits have been of primary interest to breeders in the poultry industry. It has been shown that immunization against vasoactive intestinal peptide (VIP) inhibits reproduction via neuronal and hormonal pathways (Son et al, 2016; Vistoropsky et al, 2016). The effects of VIP and its receptor (VIPR-1) genes on the reproduction traits of poultry have recently been a focus of interest (Xu et al, 2011; Ngu et al, 2015; Pu et al, 2016). Active immunization against VIP in turkey hens terminates broodiness and increases egg production (El Halawani et al, 2000). The association of VIP and VIPR-1 polymorphisms with egg production of chicken has been reviewed (Xu et al, 2011; Pu et al, 2016)
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