Effects of Supplementation with Oregano Essential Oil during Late Gestation and Lactation on Serum Metabolites, Antioxidant Capacity and Fecal Microbiota of Sows.

A total of 20 healthy white × landrace sows were evenly and randomly divided into two groups, and fed basal diets unsupplemented or supplemented with 500 g/t Meriden-Stim ® from day 100 of gestation until day 21 of lactation. Serum and fecal samples were collected from the sows on the final day for subsequent analysis. Compared to the control group, there were no significant differences in the sows' performances; however, an increase was observed in the piglets' weight at weaning ( p = 0.08). Moreover, oregano essential oil (OEO) significantly reduced the levels of urea (UREA) ( p < 0.01), total cholesterol (TC) ( p < 0.05), low-density lipoprotein (LDL-C) ( p < 0.05) and alanine aminotransferase (ALT) ( p < 0.05) in serum. In terms of antioxidant indexes in serum, the catalase (CAT) and glutathione (GSH) levels showed significant increases ( p < 0.05) while the malondialdehyde (MDA) level exhibited a decrease tendency ( p = 0.09). 16S rRNA analysis identified the specific bacteria taxa in feces. OEO significantly decreased the relative abundance of Proteobacteria and Actinobacteria at the phylum level ( p < 0.05). At the genus level, OEO significantly increased the relative abundance of Lactobacillus and Prevotellaceae UCG 003 and UCG 005 , while decreasing that of Escherichia-Shigella ( p < 0.05). Taken together, OEO supplementation in maternal diets during late gestation and lactation improved serum metabolites, antioxidant capacity and regulated the intestinal-flora balance of sows, thereby tending to increase the piglets' weight at weaning.