Simple SummaryPig production heavily depends on the reproductive performance of sows. The antioxidant capacity and hormone levels of lactating sows have an essential impact on their own health and the health of future generations. We investigate the effects of dietary probiotics and acidifiers on the production performance, colostrum components, serum antioxidant activity and hormone levels, and gene expression in the mammary tissue of lactating sows. The results showed that the dietary probiotics and acidifiers improved the growth performance of piglets, decreased the serum malondialdehyde levels, increased the superoxide dismutase contents, and increased the relative expression levels of the prolactin receptor and fatty acid synthase. In conclusion, the basal diet mixed with 200 mL/d probiotics + 0.5% acidifiers improved the production performance, colostrum components, serum antioxidant activity, and hormone levels of lactating sows. This study provides a more theoretical basis for the dietary probiotics and acidifiers’ application in the diet of lactating sows and for the sustainable and healthy development of pig farming.AbstractThe aims of this study were to test the effects of dietary probiotics and acidifiers on the production performance, colostrum components, serum antioxidant activity and hormone levels, and gene expression in the mammary tissue of lactating sows. Four treatments were administered with six replicates to 24 lactating sows. The control group (GC) received a basal diet, while the experimental groups received a basal diet with 200 mL/d probiotics (GP), 0.5% acidifiers (GA), and 200 mL/d probiotics + 0.5% acidifiers (GM), respectively. Compared with the GC, (1) the average weight of the piglets on the 21st day of lactation in the GM was higher (p< 0.05); (2) the colostrum fat ratio increased significantly (p< 0.05); (3) the malondialdehyde levels in GP and GM were lower (p< 0.05) on the 11th day; (4) on the 1st, 11th, and 21st days, the prolactin in GP and GM increased (p< 0.05); (5) on the 21st day, the relative expression levels of the prolactin receptor and fatty acid synthase were increased (p< 0.05). In summary, the basal diet mixed with 200 mL/d probiotics + 0.5% acidifiers could improve the production performance, colostrum components, serum antioxidant activity, and hormone levels of lactating sows.