Effects Of Light On Circadian Behavioral Rhythm Of Laying Ducks And Its Genetic Effects

Sansui laying duck was chosen to be the research material.Behavioral study was carried out using Media Record software to track the circadian rhythm behavior and Observer XT software to define and analyze.The changes of plasma corticosterone levels were studied by ELISA,and the changes of plasma corticosterone levels were studied under different bran content diets,different light duration and light intensity.Genomic PCR was used to analyze the SNP polymorphism and bioinformatics analysis of Cry1 gene and Bmal1 gene by hybrid DNA pooling and direct sequencing.The qRT-PCR method was used to analyze the expression of Cry1 gene and Bmal1 gene in heart,Liver,kidney,chest,leg,brain and eye,and to explore the mechanism of gene influence on the biological rhythm of laying duck.The results are as follows:1.The behavioral analysis showed that the five kinds of circadian behavior in the circadian rhythm of the duck were different with the increase of the bran content diets.The sleeping behavior,the awakening behavior and the nesting behavior were relatively stable,the laying behavior was slightly reduced,and the postpartum resting behavior slightly increased.At the same time,the number of eggs,egg weight and the number of colored eggs were reduced.As the duration of light increased,the sleeping behavior decreased,the awakening behavior and the nesting behavior were relatively stable,and the behavior of laying and postpartum resting behavior were increased,at17hL:7hD treatment to reach the peak.What was more,the number of eggs,egg weight and the number of colored eggs were increased first and then decreased,and reached the peak at 17hL:7hD.With the increase of light intensity,the reduction of sleeping behavior was small,the awakening behavior and Survival behavior remained relatively stable,laying behavior and postpartum resting behavior increased slightly,reaching the peak at 1100 lx treatment.Additionally,the number of eggs,egg weight and the number of colored eggs were increased first and then decreased,in the number of 1100 lx treatment to reach the peak.The study of the mutual transformation between the five behaviors shows that,the relationship between sleeping behavior and awakening behavior,awakening behavior and nesting behavior,nesting behavior and laying behavior,postpartum resting behavior and sleeping behavior showed a very significant positive correlation(P<0.01).The postpartum resting behavior and wakening behavior showed no significant positive correlation(R=0.19,P>0.05).There was a significant positive correlation between laying behavior and postpartum resting behavior(R=1,P<0.01).There was a significant negative correlation between nest behavior and sleep behavior(R=-0.46,P<0.05).2.Corticosterone content analysis showed that the total trend of plasma corticosterone concentration was decreasing under the treatment of different bran content diets.The total trend of plasma corticosterone concentration was decreased and the middle fluctuated slightly the treatment of different light duration.And the total trend of plasma corticosterone concentration was decreased under different light intensity treatments.It was demonstrated that the treatment of 10% bran content diets,increasing light length(17L:7D),increasing light intensity(1100 lx)could reduce the stress of laying ducks in the laying period.3.Genetic polymorphism analysis showed that there were four SNPs in the 6th exon and 7th intron of Cry1 gene and two SNPs in the first exon of the Bmal1 gene.Before and after the mutation,there were no differences,which could be considered synonymous mutation.SSCP analysis showed that there were three genotypes in the promoter region of the Bmal1 gene(defined as A,B and C).4.The differences of Cry1 gene and Bmal1 gene expression were analyzed under the conditions of different bran content diets,different light duration and different light intensity.The results showed that the expression quantities of Cry1 gene and Bmal1 gene were different in different tissues,neither in the same tissues.The expression quantity of Bmal1 gene was more stable than that of Cry1 gene in different tissues.Among them,Cry1 gene expression quantity in the kidney and eye was thehighest and Bmal1 gene expression in the brain and eye was the highest.In different fiber dietary conditions,Cry1 gene were first decreased and then increased in the tissue of heart,kidney,chest,legs,brain,eyes.Their expression quantity were rising in the kidney but gradually decreased,indicating that it may increased the body's metabolism,so increased the load of each organ.The Cry1 gene changed irregularly under different conditions,and the mechanism needs further investigation.The trend of Bmal1 gene was not changed apparently in these three conditions which its mechanism needs further exploration.