| The proteins of ApoA-I and ApoA-V are two members of the apolipoprotein family. The first one has been proposed to paly carrier role in the process of reverse cholesterol transport. The latter one, as a transporter, participates in cholersterol transduction from plasma to the ovary. A total of434Erlang Mountain hens, consisting of209SD02strain layers and209SD03strain layers were used. The effects of egg and plasma cholesterol content and some reproductive traits were investigated in laying hens. At the same time the gene variation of ApoA-I and ApoA-V genes were studied by using PCR-SSCP and PCR-RFLP and DNA sequencing methods and its accociation with plasma and egg cholesterol contants and some reproductive traits. The results were as follows:Difference analysis between the two trains showed that body weight at first egg, body weight and egg weight at300days of SD02were both significantly higher than the same strains in SD03(P＜0.05). Egg weight at first laying, egg production, hatching rate of total egg and plasma cholesterol content of SD02were both significantly lower than the SD03(P<0.05).Divided the plasma cholesterol content into five groups (35<I<70、70<II<95、95≤Ⅲ<120、120<IV<145、145<V<200mg/100ml). As the concentration of plasma cholesterol increasing, which it at the condition low content, the egg production and hatching rates showed increasing. The two traits showed decreasing when the plasma cholesterol content was morn than145mg/100ml. With the PCHO increasing the body weight at first egg showed decreasing and the egg weight of first egg showed increasing.Divided the yolk cholesterol content into five groups (10≤Ⅰ＜11、11<Ⅱ<13、 13≤Ⅲ<15、15≤Ⅳ<22mg/g yolk). The egg weight and egg yolk weight at300day both showed a rising trend with the yolk cholesterol content increasing. With the ECHO increasing, when the yolk cholesterol content over15mg/g yolk, the hatching rate of fertilized egg showed decreasing. Results showed by multiple comparison that age at first egg and egg weight at300days were significant differences among yolk cholesterol content levels(P<0.05).Eleven new genetic variation sites had been detected. Three sites detected in ApoA-1gene and eight sites detected in ApoA-Ⅴ gene. All the sits were intermediate polymorphism information content (0.25<PIC0.5).Association analysis of SNP in ApoA-I gene with some reproduction traits and cholesterol contents, the results showed that SNP1presented significant genetic effects on first egg weight (P＜0.05) and very significant genetic effects on egg production (P<0.01). In SNP2, related to egg weight at300day, hatching rate of fertilized egg and plasma cholesterol content, genotypes were significant difference (P<0.05). Different genotypes of SNP3on the egg weight at300day, hatching rate of fertilized egg and plasma cholesterol content were significantly different (P＜0.05). The result showed that different com-genotypes of ApoA-I gene had significant or very significant effects on the age of first egg, first egg weight, body weight at first egg, egg production, yolk weight, hatching rate of fertilized egg and plasma cholesterol content (P＜0.05, P＜0.01). Comparing with H3H4, age of first egg in H1H4was earlier and body weight at first egg in H1H5was lower. Comparing with H1H5, egg production in H3H4was lower and hatching rate of fertilized egg in H1H4was lower and first egg weight and egg weight at300day were lower too. Comparing with H1H1, yolk weight in H4H4was higher. Comparing with H4H4, the yolk cholesterol content was higher. Comprehensive showed that the H1H5should be the priority selection target. But the H1H4and H3H4should be the elimination selection targets.Correlation analysis between the polymorphisms in ApoA-Ⅴ gene and all the traits, the result showed that different genotypes of SNP on age at first egg, first egg weight, egg weight at300day, body weight at300day, total hatching rate, hatching rate of fertilized egg and plasma cholesterol content were significantly different (P<0.05).The result also showed that different com-genotypes of ApoA-V gene had significant effects first egg weight, egg production, egg weight at300day, hatching rate of fertilized egg and plasma cholesterol content(P<0.05). The body weight at300day in Z5Z5was significant lower than Z1Z1. And the egg production in Z5Z5was significant higher than Z1Z1, Z4Z4and Z4Z8. The first egg weight in Z1Z1was significant higher than Z4Z4. And the egg weight at300day was higher than Z4Z8. The plasma cholesterol content in Z4Z8was lower than Z8Z8. And the yolk cholesterol content in Z4Z8was significant lower than Z5Z5. It all hinges upon the breeding goals of Z5Z5whether an elimination selection target or a priority selection target by the breeding goal. Aut the Z1Z4had middle values of each trait. So it could be the priority selection target.Comprehensive showed that laying hen, with higher and lower cholesterol content in plasma and yolk, had the lower egg production and hatching rate. The hen had higher reproduction performance when plasma cholesterol content was at the range of120to145mg/100ml and the yolk cholesterol content was at the range of11to15mg/g yolk. Selection the two com-genotypes of H1H5in ApoA-I gene and Z1Z4in ApoA-V gene could improve the laying hen’s reproduction performance and regulation the cholesterol content in plasma and yolk. |
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