Transcriptome Sequencing And Differentially Expressed Gene Screening Analysis Of Ovarian Tissue In Dairy Goats During Non-breeding And Breeding Seasons

As one of the important dairy animals in my country,dairy goats have the characteristics of high milk yield,roughage resistance,and strong disease resistance,but the seasonal estrus characteristics seriously restrict their reproductive efficiency.Quality and efficiency improvement,improved breed breeding,and multiple litter culture are conducive to improving the milk yield of dairy goats and the economic benefits of sheep farming.Seasonal estrus in dairy goats is regulated by the hypothalamus-pituitary-ovarian axis.The ovary is not only the target organ for reproductive regulation in female animals,but also secretes steroid hormones to play a negative feedback role.In this study,the secretion levels of reproductive hormones in peripheral blood of 20 dairy goats in the non-breeding season and in the breeding season were measured and compared,and the morphological observation and transcriptome level detection of the ovarian tissues of 4 dairy goats in the non-breeding season and 3 dairy goats in the breeding season were performed.The key candidate genes were analyzed and screened,and the key genes,hormone secretion and follicular development regulation mechanism were preliminarily explored,which provided a theoretical basis for further elucidating the seasonal estrus of dairy goats.The specific research results are as follows:1.The average daily intake of dry matter in dairy goats has distinct seasonal characteristics.The average daily intake of dry matter in the BS group was significantly higher than that in the NBS group(P < 0.05).The secretion level of reproductive hormone FSH in the peripheral blood was significantly higher in the BS group.It was higher than that of NBS group(P < 0.01),and the secretion level of P4 in the BS group was significantly higher than that in NBS group(P < 0.01).There was no significant difference in LH and E2 secretion levels between the two groups.2.The length,width,thickness and weight of the ovarian tissue of dairy goats were not significantly different between the NBS group and the BS group;the number of medium follicles in the BS group was significantly higher than that in the NBS group(P < 0.05),the number of small follicles and large follicles in the BS group and the NBS group,the difference was not significant,the follicle morphological development in different developmental stages was not significantly different between NBS group and BS group.3.A total of 2139 known differentially expressed genes were identified in the ovary tissues of dairy goat NBS group and BS group,of which 1139 genes were up-regulated and1,000 genes were down-regulated.4.Use GO and KEGG databases to analyze the function and pathway enrichment of the screened differentially expressed genes.The enriched GO functions of differentially expressed genes mainly involve steroid biosynthesis,cellular nitrogen compound synthesis and metabolism,cellular organs,biological regulation and other types.KEGG pathway enrichment analysis showed that differentially expressed genes were mainly involved in hormone synthesis and secretion,ovarian steroid hormone synthesis in follicular development,TGF-β signaling pathway,Notch signaling pathway and other regulatory pathways.Four key candidate genes were screened,namely COMT and INHBB genes that may be involved in the regulation of reproductive hormone secretion,and AMH and BMP15 genes involved in reproductive hormone secretion and follicle development.The RT-q PCR results were correct.In summary,this experiment used high-throughput sequencing technology to sequence the transcriptome of the ovarian tissue of dairy goats in the non-breeding and breeding seasons,and screened out key candidate genes such as COMT,BMP15,AMH and INHBB,which may be involved in reproductive hormones.It plays an important role in the secretion,follicular development,and regulation of the ovarian function of dairy goats in seasonal reproduction.This study provides a reference for revealing the potential regulatory mechanism of the seasonal reproductive behavior of dairy goats and improving the reproductive performance of dairy goats.