Study On The Molecular Markers Of Egg-laying And Egg Quality Traits In Wenchang Chicken

Egg production and egg quality traits of 120 hens from a pureline of Wenchang layers (Chinese indigenous chicken breed) were collected in testing center of poultry quality, Ministry Agriculture of China. Data on egg production including total egg production, continual egg-laying, and number of double-yolked eggs were collected daily using trap nests to identify individual bird. The data for individual hen were collated over a 5-month period and recording commenced at 25 weeks of age and all birds were treated the same. Egg quality including egg weight(EW),shell weight (SW),shell thickness (ST),shell strength (SS),haugh unit (HU),egg shape index (SI),yolk weight (YW) and yolk color (YC) were measured at the age of 55 weeks.A candidate gene approach was used to determine whether specific loci explain responses in the egg production and egg quality traits of Wenchang chicken in its pure-line population. PCR-RFLP and PCR-SSCP techniques were conducted on nine candidate genes that were gonadotropin releasing hormone receptor (GNRHR),Neuropeptide Y(NPY),Growth hormone receptor(GHR),prolactin(PRL),Estrogen Receptor (ESR),insulin-like growth factor-1(IGF-I),transforming growth factorβ-2(TGFβ-2),transforming growth factorβ-3(TGFβ-3)and transforming growth factorβ-4(TGFβ-4)respectively. And microsatellite primers of 20 pairs in total have been employed to perform electrophoresis to determine the genotype of individual. This study was designed to identify the polymorphisms of each gene and microsatellite locus and found genetic effects on the traits. The results is as following.Polymorphic sites were found in each genes except for TGFβ-2 and TGFβ-4 andχ~2 analysis among these gene locus indicated that only the frequencies of GNRHR,NPY,PRL,ESR,IGF-I and TGFβ-3 fit Hardy-Weinberg equilibrium. It suggested that allele and genotypes frequencies of these sites were stable. In addition,association analysis of the...