The network regulation mechanism of the effects of heat stress on the production performance and egg quality of Jinding duck was analyzed by miRNA-mRNA

To explore the differential regulation mechanism of heat stress on the egg production perfor-mance and egg quality of Jinding ducks, 200 Jinding ducks (360-day-old) in good health and with similar body weights and a normal appetite were selected and randomly divided into a control (normal temperature [NT]) group (20 degrees C -25 degrees C) and a heat stress (HS) group (32 degrees C-36 degrees C), with 4 replicates in each group and 25 ducks in each replicate. The pretrial period was 1 wk, and the formal trial period was 4 wk. At the end of the 4th wk, 12 duck eggs were collected from each replicate to determine egg quality. Pituitary and ovarian tissues of Jinding ducks were collected, transcrip-tome sequencing was performed to screen differentially expressed miRNAs and mRNAs related to high tempera-ture and heat stress, and a competitive endogenous RNA regulatory network was constructed. The sequencing data were verified by qRT-PCR method. The following results were obtained: (1) Compared with the NT group, the HS group had a significantly lower laying rate, total egg weight, average egg weight, total feed intake, and feed intake per duck (P < 0.01), an extremely significantly higher feed-to-egg ratio (P < 0.01), and a higher mortality rate. (2) Compared with the NT group, the HS group had an extremely significantly lower egg weight, egg yolk weight, eggshell weight, and eggshell strength (P < 0.01) and an extremely significantly lower yolk ratio and eggshell thickness (P < 0.01, P < 0.05); however, there was no signif-icant difference in the egg shape index, Haugh unit or pro-tein height (P > 0.05). (3) A total of 1,974 and 1,202 genes were identified in the pituitary and ovary, respectively, and there were 5 significantly differentially expressed miRNAs. The differentially expressed genes were involved in the argi-nine and proline metabolism pathways, ether lipid metabo-lism pathway, and drug metabolism-cytochrome P450 pathway, which are speculated to be related to the egg pro-duction performance of Jingding ducks under high-temper-ature heat stress. (4) Novel_221 may target the PRPS1 gene to participate in egg production performance; novel_168 and novel_289 may target PIGW; novel_289 may target Q3MUY2; and novel_289 and novel_208 may target PIGN or genes that may be related to high-tempera-ture heat stress. (5) In pituitary tissue, upregulated novel_141 (center of the network) formed a regulatory net-work with HSPB1 and HSP30A, and downregulated novel_366 (center of the network) formed a regulatory net-work with the JIP1 gene. In ovarian tissue, downregulated novel_289 (center of the network) formed a regulatory net-work with the ZSWM7, ABI3, and K1C23 genes, novel_221 formed a regulatory network with the IGF1, BCL7B, SMC6, APOA4, and FARP2 genes, and upregu-lated novel_40 formed a regulatory network with the HA1FF10 gene. In summary, heat stress affects the produc-tion performance and egg quality of Jinding ducks by regu-lating the secretion of endocrine-related hormones and the release of neurotransmitters as well as the expression of miRNAs and mRNAs in pituitary and ovarian tissues. The miRNA-mRNA regulatory network provides a theoretical basis for the molecular mechanism that regulates the stress response in pituitary and ovarian tissues, egg quality, and production performance under heat stress.