Transcriptome analysis of oviduct in laying ducks under different stocking densities.

1. High stocking densities can lead to animal stress responses and lead to changes in bird behaviour, egg production and the fertility of laying birds. The oviduct plays a crucial role during the process of laying eggs. Therefore, it is essential to know how high stocking density affects oviduct function.2. In this study, a total of 2,115 differentially expressed genes (DEGs) were identified in duck oviduct tissues between different stocking density groups. These genes are mainly enriched in membrane components, calcium ion binding, cytokine-cytokine receptor interaction and focal adhesion. These pathways were closely related to the formation of eggs. This indicated that secretion and material transport functions of the oviduct are affected under high-density stocking. Further analysis showed that a total of 408 genes related to the transportation process were expressed in the oviduct, of which 96 genes were differentially expressed (LogFC≥1, P < 0.05). Forty-two of these DEGs belonged to the solute carrier family. The data showed that the expression of 31 transcripts was different between the two density groups. Expression of KCNJ15, SLC26A8, and TRPM5 was only seen in the high-density group (8/m2), while ATP13A3 and KCNIP2 were only expressed in the low-density group (4/m2).3. Consequently, high stocking density may affect the expression and splicing of genes related to molecular transport in the oviduct.