| Muscovy duck is native to tropical areas of Central and South America.After introduced to China,it is mainly raised in the south of China.Muscovy duck is an excellent meat duck,which has the characteristics of good meat quality,high nutritional value,delicious meat taste,and has the advantages of large weight,coarse feeding tolerance and high feed conversion rate.In recent years,Muscovy duck farrning has gradually received attention,and its breeding scale has increased year by year,which has high economic value in the modern poultry industry.Due to the low egg-laying rate,the long rest period in winter and the lack of systematic breeding,the difference of population egg production is large,which seriously affects the development of the ducks industry.Therefore,the study on the egg-laying traits and genetic variation of genes closely related to the egg-laying performance of white-feather Muscovy duck laid a foundation for the scientific selection and breeding of white-feather Muscovy duck in the early stage.In this study,the egg-laying rate and cumulative egg production curve of white-feather Muscovy duck from 28 to 51 weeks were fitted and analyzed to reveal the egg-laying rule of white-feather Muscovy duck.Accoeding to the egg-laying rule,the feeding scheme can be adjusted to give full play to its egg production potential.The differentially expressed genes were screened by transcriptome sequencing of high and low yielding white-feather Muscovy ovary,and so as to understand the genes that play physiological roles in the ovaries of white-feather Muscovy duck and provide theoretical basis for molecular breeding of white-Muscovy duck.Through the SNP study of GDF9,TGFB3 and MTNR1A,we can understand the impact of these genes on the production of white-feather Muscovy duck and the breeding of white-feather Muscovy duck with high egg yield Provide data reference.1.After fitting the weekly egg-laying rate and cumulative egg production curve of the white-feather Muscovy duck,it was concluded that the optimal fitting model of weekly egg-laying rate of white-feather Muscovy duck in this breeding group was Yang ning model(y_t=0.913*exp(-0.037*t)/[1+exp(-0.856*(t-3.591))]).The Von Bertalanffy model(y_t=103.384*[1-0.851*exp(-0.099*t)]~3)had the best fitting effect on the cumulative egg production of white Muscovy duck,and the predicted inflection point age of the cumulative egg production was 36.467 weeks.2.The transcriptome of high and low yielding white-feather Muscovy ducks was sequenced,and 296 DEGs were screened.160 genes were up-regulated and 136 genes were down-regulated in the ovary of high yielding white-feather Muscovy ducks.133 DEGs obtained GO function notes,which were enriched into 492 GO terms.The significant enrichment of differentially expressed genes in KEGG was mainly involved in six signaling pathways,among which the PI3K-Akt signaling pathway is closely related to animal reproduction.Real-time quantitative fluorescence qPCR detection of DEGs,the expressions of POSTN,COL4A1,SMOC1,CPEB2 and C1QTNF3 in the ovaries of high yielding white-feather duck were significantly up-regulated compared to low yielding(P<0.05),the expressions of CEBPD were significantly up-regulated compared to low yielding(P<0.01),and the expressions of MC2R were significantly down-regulated compared to low yielding(P<0.01),which was consistent with the transcriptome results.It was concluded that the selected differentially expressed genes POSTN,COL4A1,SMOC1 and SDC4 regulate the physiological functions of the ovary in the PI3KAkt signaling pathway,and the differential expression of CPEB2,C1QTNF3,CEBPD and MC2R genes affected the ovarian function of white-feather Muscovy duck.3.In GDF9 gene,the g.3340814 C/T site was significantly associated with egg number at 280 days and 300 days(P<0.05),but not with weight at 280 days(P>0.05).The g.3341687 G/A was not associated with the number of eggs at 280 days、300 days and the weight at 280 days(P>0.05).Four SNPs of the TGFB3 gene(g.27959496 G/A,g.27965097 G/A,g.27965604 C/T,g.27970706 C/T)and two SNPs of the MTNR1A gene(g.19463377 G/A,g.19463425 C/T)was not associated with the number of eggs at 280days、300 days and the weight at 280 days(P>0.05).The polymorphic site of GDF9 gene can be used as a potential molecular marker for egg laying traits in white Muscovy ducks. |
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