| Based on the characteristics of some blue-shell eggs and the purpose of efficient utilization of excellent germplasm of Xuefeng silky fowls,it is proposed to establish a pure system of Xuefeng silky fowls blue-shell,to lay the foundation for subsequent cultivation of new bule-shell eggs of Xuefeng silky fowls(series).In this study,the performance correlation and SLCO1B3 methylation degree analysis of the Xuefeng silky fowls blue shell breeding population(L1)were conducted to improve its reproductive performance and the greenness of the egg shell,aiming to provide basic data for the breeding of pure blue shell lines and speed up the selection process.1.Correlation analysis of body size of L1 generationThe analysis of blue shell laying hens of L1 showed:(1)The average body oblique length(cm),tibia circumference(mm),and number of eggs(number)of homozygous and heterozygous individuals were 15.69±0.69,15.61±0.55;33.08±1.38,32.53±1.10;51.37±7.41,48.02±6.75,there was a significant difference between the two genotypes.(P<0.05);(2)The correlation analysis of body mass body size and egg performance shows that the correlation coefficient between the slant length of the homozygous individuals and the number of eggs was r=-0.148,showing a significant negative correlation(P<0.05),heterozygous individuals the correlation coefficient between body oblique length and age at first laying of delivery was r=0.123,showing an extremely significant positive correlation(P<0.01).The above suggested that oblique body length can be used as a key body size indicator for pure blue shell eggs.2.Correlation between eggshell color and biliverdin content of eggshellThe results of the correlation analysis between eggshell biliverdin content and shell color values L,a,b were as follows:(1)There was an extremely significant differences in the biliverdin content(mg/g)between the homozygotes and heterozygotes of the blue shell,which were(0.067±0.017)mg/g and(0.014±0.014)mg/g(P<0.01);(2)The regression equation between the eggshell color a value and the biliverdin content was y=-0.1128x+0.06825,R~2=0.764(homozygous),y=-0.324x+0.131,R~2=0.727(heterozygous);(3)The analysis of the correlation between the shell color L,a,b values of the homozygous and heterozygous of the blue shell eggs and the biliverdin content of the egg shell showed that only the a value and the biliverdin content were an extremely significantly negative correlation(P<0.01),the correlation coefficients were r=-0.839,r=-0.752,respectively.3.Effect of promoter methylation of SLCO1B3 gene on gene expression activityTo evaluate the expression of the SLCO1B3 gene in the shell glands of Xuefeng silky fowls and the degree of methylation in its promoter region,and to establish the relationship between the degree of methylation and the color of the eggshell.The main results were as follows:(1)In two genotypes,SLCO1B3 gene expression levels in blue shell homozygous were significantly higher than heterozygous individuals(P<0.05);(2)The methylation levels of CpG Ⅲ islands were 12.38%and 15.2%in homozygotes and heterozygotes,respectively,and CpG Ⅴ islands were 12.4%and 14.64%in the two genotypes,respectively;(3)Sites 7,8,9,10,11 in CpG Ⅲ island have extremely significant or significant correlated with the shell color L and a value,and sites 8,10,11 were an significantly negatively correlated with the gene expression;Only position 6 in CpG Ⅴ island was correlated with eggshell color and gene expression;(4)The prediction results show that the 8 and 10 sites in CpG Ⅲ can bind to TBP and RF,and were significantly related to gene expression and eggshell color value,suggested that its methylation modification may affect Xuefeng silky fowls the greenness of the egg shell.The above research results provided data for quickly improving the reproductive performance and greenness of the Xuefeng silky blue shell population based on performance indicators such as body oblique length and eggshell a value,as well as revealing and using the law and mechanism of blue shell eggshell color differences provide date support,it is expected to play an important role in the efficient and accurate breeding of Xuefeng silky blue shell pure line,and it has good application value. |
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