The Preliminary Study On Hybridization Of Changshun Blue-Eggshell Chicken And Recessive White Feather Dwarf Chicken

Dwarf chickens(dwdw)is widely used in the cross systems of the layer and broiler production because of their genetic advantages such as light body weight,small body size,less feed consumption,and good adaptability and strong disease resistance.Changshun blue-eggshell layer chicken in Qiangnan,Guizhou,China with characteristics of delicious egg and meat is the excellent local breed in the many blue-eggshell layers and is favored by the market and has certain market popularity in the Guangdong-Guangxi area.The researches about the breed is still at the preliminary stage.There is no relevant research report on the cross system of dwarf chickens and Changshun blue-eggshell layer today.In order to effectively and quickly develop the green shell chicken,in this paper,the performance characteristics of the dwarf laying hens initially introduced in Guizhou were studied,and at the same time,the production performance of Changshun blue-eggshell hens that had been bred and purified by two generations was studied,and on this basis,a preliminary study was made on the crossbreeding scheme of Changshun blue-eggshell laying chicken and white feather recessive dwarf chicken.In this study Changshun blue-eggshell chickens were used as male parents,and white feather recessive dwarf chickens were used as female parent to carry out cross-breeding experiment.The meat performance,egg production performance and regular egg quality of the offspring were measured and analyzed,and the differences in the production performance of their commercial generations and pure offspring of Changshun blue-eggshell chickens were initially discussed.The key genes for heme synthesis,Ferrochelatase(FECH)and Ovotransferrin(OF),which form the color of eggshell,were used as RT-PCR analysis to explore the molecular mechanism of eggshell color formation,provide a theoretical basis and reference for the further development of Changshun blue-eggshell chicken.The results show:1.Significant differentiation appeared in the feather color and the shin color in the hybrid offspring.The hybrid offspring was similar to the Changshun blue-eggshell chicken in its growth and body shape;and which's body length,and keel length,and back width,and body weight were significantly higher than those of white feather recessive dwarf chickens on 112 days(P<0.05).2.The trend of weight variation of male offspring was estimated optimally by the Logistic model and the GomPertz model(R~2=0.996);Logistic model estimates the growth curve of the hybrid offspring and the Changshun blue-eggshell hen was the best(R~2=0.992,R~2=0.999).The logistic model and Bertalanffy model was used to estimate the growth curve of the Changshun blue-eggshell rooster with a high degree of fit(R~2=0.998);the Bertalanffy model and the GomPertz model for white dwarf rooster's growth curve had the highest degree of fit(R~2=0.998);it had the highest curve fitting with GomPertz model to white dwarf hen's weight gain(R~2=0.989).3.The slaughter rate,percentage of half eviscerated yield and percentage of eviscerated yield of the the hybrid offspring rooster were significantly higher than that of the Changshun blue-eggshell chicken(P<0.05);rooster and hen's leg ratio,wing rate,leg muscle ratio,and chest muscle ratio were all improved compared to Changshun blue-eggshell chicken(P<0.05)4.The age at first egg of hybrid offspring was relatively earlier than that of the parent Changshun blue-eggshell chicken,but it was not significant.The peak egg production rate(79.43%)(egg production rate above 70%)and egg production peak last time(6.39 weeks)were longer than Changshun blue-eggshell laying hens(74.28%,5.54 weeks).5.The degree of fitting of Yangning model to fit the egg production rate of Changshun blue-eggshell chicken was the highest(R~2=0.993);the degree of fitting of Yangning model and McMillan model to fit the laying rate of recessive white feather dwarf chicks were the highest degree(R~2=0.993);and the degree of fitting of McMillan model to fit the CSBW laying rate was the highest(R~2=0.998).6.At 35 weeks of age,the eggshell intensity,eggshell thickness,protein ratio,protein height,and Haugh unit of the hybrids were significantly smaller than the parental(P<0.05);the yolk index and egg yolk ratio were significantly higher than the parental Changshun blue-eggshell chicken(P<0.05).7.White feather recessive dwarf chickens lack the exon 10 and 3'UTR regions of the GHR gene base mutation of exon 5,which is the function of the dw gene,resulting in a small size,light weight,and less material consumption.8.The OF gene was expressed in the eggshell glands of Changshun blue-eggshell hens producing green shell eggs,and was significantly higher in the dark green group(P<0.05).Ferrioxygenase(FECH)was produced in dark green,white green,yellowish green,and light pink green shell eggs were all expressed in the eggshell glands of Changshun blue-eggshell hens.In conclusion,through the study of the two parents and the first generation of crosses,the first generation of hybrids showed differences in feather color and shin color compared to the two parents,but they were basically similar to the Changshun blue-eggshell hens;in terms of growth and the conventional egg quality basically retained the quality of the Changshun blue-eggshell chicken and basically inherited the recessive white feather short chick in the carcass performance and laying performance.In general,the hybrid 1 had certain hybrid superiority both in growth and in production performance,In terms of egg color,its green shell is relatively high and can be used as imitation soil egg;but in the future,it will be necessary to re-purify Changshun blue-eggshell chicken and improve the appearance of hybrid offspring,so as to be introduced into large-scale production.