| There are many species of local chicken breeds in China, but poor reproductive performances of majority local chicken breeds, especially the poor egg production, have large effects on high quality chicken industry development. However, it's difficult to improve reproduction traits by conventional breeding because of their low heritability. With the development of DNA molecular marker technology and detection, marker-assisted selection (MAS) has been developed quickly and used in genetic improvement of chicken performance with low heritability.In avian, PRL (prolactin) is especially crucial for reproduction traits such as egg production. PRLR (prolactin receptor) and VIP (vasoactine intestinal peptide) are closely related with PRL signal transduction pathway, in which PRLR is the receptor for PRL, and VIP is a release factor for PRL. Therefore, in this study, PRLR and VIP gene were selected as candidate genes for egg production and body weight trait, and body weight at 134 days and at 65 weeks, egg production within 65 weeks and within 300 days were examined in Si Ming Xiang chicken B strain from Zhejiang Shennong animal husbandry limited company. Ligase detection reaction (LDR) was used to detect gene polymorphism, filter SNPs and genotyping. The associations between these SNPs polymorphisms and egg production traits and body weight traits were analyzed by SAS software. Results were obtained as follows:1.4 SNPs (C11390G, A14952G, A14969C, A14984G)in PRLR gene and 2 SNPs (A-3458G, C2099G) in VIP gene were detected in Si Ming Xiang chicken B strain.2. Linkage disequilibrium analysis showed SNP2(A14952G),SNP3 (A14969C) and SNP4 (A14984G) were in complete linkage.3. Association analysis for PRLR gene showed that SNP2/SNP3/SNP4 was significantly associated with egg production within 300 days (P<0.05). Egg production within 300 days of genotype G/A/G was significantly higher than that of A/C/A with 7 eggs (P<0.05). SNP1 (C11390G) had no significance on the all traits detected (P>0.05).4. Association analysis for VIP gene showed that body weight at 65 weeks had significant difference among different genotypes in A-3458G locus (P<0.05). Hens with AG genotype had a higher body weight at 65 weeks of 100g than GG genotype (P<0.05). As for C2099G locus, there was no significant difference among different genotypes in various traits detected (P>0.05).5. A total of 3 haplotypes for four SNPs of PRLR gene was detected:H1(CACA), H2(GACA) and H3(CGAG). Association analysis showed different haplotypes had significant differences on egg production within 300 days (P<0.05). The predominant haplotypes were H3>H2>H1 successively, in which hens of haplotype H3 had 7.33 eggs more than that of H1. It indicated that H3 of PRLR gene was the best haplotype for egg production, which is the potential marker for laying performance.6. A total of 5 combined genotypes for 2 SNPs of VIP gene was detected. Association analysis showed that there was no significant difference among different combined genotypes in various traits detected (P>0.05).7. Correlation analysis showed that body weight was significantly negative correlated with egg production, in which egg production within 65 weeks was significantly negative correlated with body weight at 134 day (P<0.05) and body weight at 65 weeks (P<0.05). Body weight at 134 day was highly significantly correlated with body weight at 65 weeks with a correlation coefficient of 0.9129 (P<0.01). |
PDF Full Text Request