Similarly, our results showed that there appeared to be more pronounced positive associations between the splenic histological parameters (including the ALA, ALD, TLA, and TAD) and the mRNA expression levels of several key immune-related genes (HSPA2, MYD88, NGF, SPI1, and VEGFA) in geese reared under MRS than under CRS. This evidence concerns the gene HSPA2 and congenital rubella syndrome.