Chicken Ghr Gene, Esr Gene And Igf-¢ñ Mrna And Egg Production Performance

Egg production 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 Wenchang chicken. 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.A candidate gene approach was used to determine whether specific loci explain responses in the egg production traits of Wenchang chicken in its pure-line population. PCR-RFLP and PCR-SSCP techniques were conducted on candidate genes that were Growth hormone recepto(rGHR),Estrogen Receptor (ESR),insulin-like growth factor-1(IGF-I)respectively. This study was designed to identify the polymorphisms of each gene locus and found genetic effects on the traits. The results is as following.Polymorphic sites were found in each genes andχ² analysis among these gene locus indicated that only the frequencies of ESR,IGF-I fit Hardy-Weinberg equilibrium. It suggested that allele and genotypes frequencies of these sites were stable. In addition,association analysis of the these gene polymorphism with egg production was conducted in Wenchang chicken, Two genetic molecular markers of egg production in Wenchang chicken were primarily confirmed which were 5' flanking region of ESR and 5′UTR of IGF-I.The results with GLM analysis showed that such significant effects of genes'marker as followsESR polymorphism has significant effect on egg production trait and average days of continual egg-laying (ADCE). The ESR F₁F₃ genotype had more eggs (300d) at 88.59 compared to 80.43 for F₂F₂ (P<0.05). The ESR F₁F₃ genotype had longer ADCE at 3.56 compared to 2.38 for F₂F₂ (P<0.01). IGF-I polymorphism has additive effect on egg production trait, also has dominant effect on eggshell weight and eggshell stress, The IGF-I PstI H₂H₂ genotype had greater number eggs (300d) at 89.03 compared to 82.61 for PstI H₁H₁ (P<0.05) and PstI H₂H₂ genotype also had greater number eggs (400d) at 137.84 compared to 127.82 for PstI H₁H₁ (P<0.05). The IGF-I PstI H₂H₂ genotype had longer ADCE at 3.38 compared to 2.96,2.78 for PstI H₁H₁ and H1H2 (P<0.05) .GHR polymorphism has additive effect on number of double-yolked eggs (DYE), The GHR HindIII C₁C₁ genotype had greater DYE at 1.00 compared to 0.30 for HindIII C2C2 (P<0.05).