Identification Of Early-and Late-feathering Population And Comparative Analysis Of Feather Development,Growth And Reproductive Performance In Beijing-You Chickens

Establishment of early-and late-feathering lines by phenotypic selection or molecular marker assisted selection has being widely performed in chickens breeding.Previous studies showed that the performance differences of early-and late-feathering lines varied with varieties.The Beijing-You chicken is one of the most important indigenous chicken breed in China,while the feather characteristics of early-and late-feathering Beijing-You chickens and the effect of feathering gene on production performance was less examined.In order to provide basic data for breeding and fine housing of Beijing-You chickens,the pure line of Beijing-You chickens was used here to compare the feather development,growth and reproductive performance of early-and late-feathering chickens.The main research and results are as following.1.The identification of early and late feathering Beijing-You chickens and their feather development characteristics.According to the relative length characteristics of the primary feathers and the coverts,the newborn chicks were identified and divided into early-and late-feathering subgroups,their genotype was further confirmed by PCR.Their feather development was traced.The results showed that the early-and late-feathering accounted for 25%and 75%of females Beijing-You chickens,respectively,and 11.6%and 88.4%of males,respectively.The majority of late feathering hens were inverted length type（M2,the primary feathers are shorter than the coverts）,and there were a few identical length type（M1,the primary feathers are as long as the coverts）,and no-primary feather type（M3,the primary feathers are missing）.Before 7 days of age,the length difference between the primary feathers and the coverts of early-and late-feathering was increasing with age,indicating that it is still possible to identifying the early-and late-feathering before 7 days of age.The primary feather length of early feathering chickens was higher than that of late-feathering chickens within 21 days old（P<0.05）.At 28 days,there was no significant difference between M1 and M2,but M3 was still shorter than that of early feathering chickens（P<0.05）.2.The effect of early and late feathering on growth and production performance of Beijing-You females.The egg production performance including age at the first egg,egg number until 43 and 52 weeks of age,clutch traits were calculated according to the individual egg production records.Compared with late-feathering,the body weight of early-feathering Beijing-You chickens was heavier after 70 days of age（P<0.05）,and the age at the first egg was significantly earlier（P<0.05）,but the egg number to 43weeks was lower（P<0.05）.Except that the egg shape index of early-feathering hens was higher than that of late-feathering ones（P<0.05）,there was no significant difference in other egg quality traits.3.Effects of early and late feathering on growth and reproductive performance of Beijing-You cocks.There was no significant difference in body weight between early and late-feathering cocks in 018wk（P>0.05）.At 22 wks of age,the semen volume and sperm motility of late-feathering Beijing-You cocks(14.70×10⁸·m L^-1)were higher than that of early-feathering cocks(13.80×10⁸·m L^-1),but the difference was not significant（P>0.05）,and the semen density was significantly higher than that of early-feathering cocks（P<0.01）.There was no significant difference in semen quality at 43 weeks of age.In conclus,The results of the present study showed that growth and reproductive performance of Beijing-You chickens could be affected by feathering phenotype.The early-and late-feathering Beijing-You chickens should be differentiated in breeding direction and production management.The underlying mechanism of feathering genes on those traits needs further investigation.