Study On The Selection Of Green Shell Traits In Xiaoxiang Within The Major Gene SLCO1B3 Marker

Xiaoxiang chicken is a landrace in Hunan province, and has many excellent characteristics. In order to take full advantage of the excellent characteristics better, the molecular identification was used through blue-shelled lines by selection and breeding. We want to improve production performance based on conservation population of the xiaoxiang chicken; the relationship between genes and production traits of Xiaoxiang chicken were analyzed at a molecular level to provide certain theoretical basis to genetic markers of blue shell traits of Xiaoxiang chicken. The SLCO1B3 gene was selected as marker locus point for the purification of the blue shell traits in Xiaoxiang.1. In this study, the genetic determination of eggshell's coloration of Xiaoxiang chicken was explained. The result provides a theoretical basis to study on the breeding of Xiaoxiang chicken at a molecular level. The gene mutation of blue-shelled Xiaoxiang was detected and analyzed by means of PCR amplifications and DNA sequencing. The results show that an EVA-HP insertion in SLCO1B3 was found in the blue-shelled chickens. The genotypes were LC/LC and N/LC. The frequency of genotypes LC/LC(425bp) were 0.172,N/LC were0.521, N/N were 0.307 in the Xiaoxiang chicken group. Xiaoxiang chicken group which had a blue shell rate 47.6% was in Hardy-Weinberg equilibrium by chi square test. The results of this study will be provided theoretical basis and technical support for the marker-assisted selection of green shell traits in future.2. The SLCO1B3 gene marker was used in the purification and breeding of blue shell traits. Before the breeding a family must be established, we called it the first family. After the multiplication descendant in the family, we got the F1 group. The PCR products of F1 with the SLCO1B3 marker and all appeared 3 genotypes. Guided by the genotypes the blue shell traits of F1 group were bred and selected. In the breeding process, two schemes were applied. With two schemes we tested chickens generation after generation by the PCR products, the N/N genotype was obsolete in the process, the blue-shelled genotype got a higher frequency. After the selection in two generations the frequency of genotypes were quite different: LC/LC(425bp) were0.350, N/LC were0.446, N/N were 0.204 in the F1group; LC/LC(425bp) were0.793, N/LC were0.105, N/N were 0.012 in the F2 group.The blue shell rate has increased from 79% in F1 to 99.8% in F2.3. In our study, different genotype effects were studied with egg performance record through correlation Analysis. Genotypes of SLCO1B3 gene didn't show a significantly effect on the age at first laying, 240 days weigh,300 days weigh, egg number at 240(P>0.05).But the age at first laying and 240 days, 300 days body weight of allele LC had the higher trend than allele N, and LC/LC genotype had significantly higher egg production,egg number than N/LC genotype and N/N genotype.