Breeding Study Of Changshun Blue-eggshell Chicken

Blue-eggshell eggs were belong to top-grade,popuLar marketing with bright prospect in many large and medium-sized cities in China.Now there are limited breeds or complete set lines for the blue-eggshell laying hen,it's eggshell colors were controlled by polygenes,but the molecuLar formation mechanism of mutiple-eggshell color has not yet to be completely clarified.Changshun native blue-eggshell laying hens were preliminarily studied for their of appearance and production in Guizhou province.Based on previous work,primary research work were focus on the low blue-eggshell rate,low laying rate and inordinately eggshell colors.These programs included the improvement of the blue-eggshell rate by conventional breeding together with EAV-HP fragment molecuLar marker,the growth ruLe and the egg-laying ruLe by fitting the growth model and the egg-laying model,the egg quality and the content of eggshell pigment for marketing reference,as well as for the causet of mutiple-eggshell colors.Finally,in order to clarify the molecuLar expression mechanism of the mutiple eggshell color,the expression profiles of heme oxygenase 1?HO-1?gene and biliverdin reductase A?BLVRA?were studied using RT-PCR in eggshell gland.The resuLts were as follows:1.The homozygous cocks were selected in F₀ generation by conventional breeding together with EAV-HP fragment molecuLar marker,the blue-eggshell hen were selected by phenotype breeding in F₀ generation,the homozygous genotype frequency of F₁ generation cock were 10.1%and 11.22%more than those in F₀ generation,respectively.These had accelerated breeding.2.The most suitable growth model for hen and cock was Gompertz model and Logistic model,respectively.The most suitable egg production curve was McMillan model in F₁generation.3.In the F₁ generation,the egg shape index in the blue group was significantly bigger than that in the brown group?P<0.05?,while the yolk color in the brown group was significantly higher than that in the greenish-brown group?P<0.05?.Each of the?b value,?E value and protoporphyrin concentration in the greenish-brown group and the brown group was extremly significantly higher than that in the blue group?P<0.01?,but their?L values was extremly significantly less than that in the blue group?P<0.01?,respectively.?a value of the three groups were in the following order:brown group>greenish-brown group>blue group,and their differences were extremely significant?P<0.01?.For comparison within the blue-eggshell group,egg size and eggshell thickness of the dark blue group were extremely significantly higher than those of the light green group?P<0.01?,while the yolk color of the light green group was extremly significantly higher than that of the dark green group?P<0.01?.?L value and?a value of the dark green group were extremely significantly less than those of the light green group?P<0.01?,while its?b value,?E value,protoporphyrin concentration and biliverdin concentration were extremely significantly higer than those of the light green group?P<0.01?.4.?L value was extremely significantly negatively correlated to other indexes?P<0.01?,?E value and protoporphyrin concentration were extremely significantly positively correlated to other indexes?P<0.01?,?a value showed no significant correlation to biliverdin concentration?P>0.05?,but was extremely significantly positively correlated to other indexes?P<0.01?,and?b value shows significantly positive correlation to biliverdin concentration?P<0.05?,while extremely significantly positive correlation to other indexes?P<0.01?.5.Relative expression quantity of HO-1 gene of the greenish brown group and the light green group in the uterine were extremely significantly higher than that of the dark green group and the brown group?P<0.01?,while the relative expression quantity of BLVRA gene of the light green group was extremely significantly higher than that of the other three groups?P<0.01?.These resuLts showed that it was a feasible scheme to use EAV-HP fragment molecuLar marker to increase the blue-eggshell rate in Changshun blu-eggshell laying hen.Changshun blue-eggshell chicken had potential development for egg production and meat production,and can developing different specialized lines by further purification and selection.Changshun blue-eggshell eggs had the characteristics of high-quality eggs,and the egg quality had a little difference between various of eggshell color groups.The reason of the greenish-brown eggshell was caused by combination with the high concentration of protoporphyrin and biliverdin.?a value was an ideal index standing for the eggshell protoporphyrin content instead of the eggshell biliverdin content in muLti-type eggshell color breeding in the Lab color system.HO-1 and BLVRA were important candidate genes for selecting light green-eggshell eggs and greenish-browneggshell eggs.