Silymarin Modulates Microbiota in the Gut to Improve the Health of Sow from Late Gestation to Lactation

Abstract

Inflammatory responses reduce milk production in lactating sows. Silymarin may modulate inflammatory reactions. Here, we aimed to verify whether dietary silymarin supplementation could alleviate inflammatory responses in lactating sows through microbiota change in the gut. We also investigated how silymarin impacts inflammatory response in lactating sows. One hundred and ten sows were randomly assigned to a control diet (basal diet) or treatment diet (basal diet and 40 g/d silymarin) from the 108th day of gestation to weaning. Blood, milk, and feces from sows were collected for analysis. It was shown in the results that dietary silymarin supplementation decreased the level of pro-inflammatory cytokine IL-1β (p < 0.05) on the 18th day of lactation in the blood of the sows. Dietary silymarin supplementation tended to decrease (p = 0.06) somatic cell count in the colostrum of sows. Dietary silymarin supplementation reduced the gut bacterial community and the richness of the gut microbial community (p < 0.01) using 16S rRNA gene sequencing. The fecal microbes varied at different taxonomic levels in the lactating sows with silymarin supplementation. The most representative changes included an increase in the relative abundance of Fibrobacteres and Actinobacteria (p < 0.05) and tended to reduce the relative abundance of Spirochaetaes and Tenericutes (p = 0.09, 0.06) at the phylum level. It is suggested that dietary silymarin supplementation in late gestation until lactation has anti-inflammatory effects in lactation sow, which could be associated with the modulation of gut microbiota.

Keywords: inflammation; microbiota; silymarin; sow.

Figure 1

Dietary silymarin supplementation modulated microbiota diversity in lactation sow. (A) A Venn diagram was generated to describe the common and unique OTUs between the treatment groups. (B) The effect of silymarin on the observed species. CTL, sow fed the basal diet; TRT, sow fed basal diet with silymarin 40 g/d from late gestation to lactation. ** are significantly different (p < 0.01).

Figure 2

Dietary silymarin supplementation modulated the microbiota alpha diversity index of lactation sow, including richness (ACE, Chao 1 index) and diversity (Shannon, Simpson index). (A) ACE index: p < 0.01. (B) Chao 1 index: p < 0.01. (C) Shannon index: p = 0.097. (D) Simpson index: p = 0.39. n = 10. CTL, sow fed the basal diet; TRT, sow fed basal diet with silymarin 40 g/d from late gestation to lactation. ** are significantly different (p < 0.01).

Figure 3

Dietary silymarin supplementation modulated microbiota beta diversity in lactation sow. (A) Beta diversity analysis based on Weighted Unifrac distance. (B) Principal coordinates analysis of each sample based on unweighted UniFrac metric. n = 10. CTL, sow fed the basal diet; TRT, sow fed basal diet with silymarin 40 g/d from late gestation to lactation.

Figure 4

16S rRNA gene analysis revealed phylum-level differences in lactation sow feces between treatments. n = 10. CTL, sow fed the basal diet; TRT, sow fed basal diet with silymarin 40 g/d from late gestation to lactation.

Figure 5

Analysis of distinct species between treatment groups at the phylum level. n = 10. CTL, sow fed the basal diet; TRT, sow fed basal diet with silymarin 40 g/d from late gestation to lactation.

Figure 6

Analysis of distinct species between treatment groups at the genus level. n = 10. CTL, sow fed the basal diet; TRT, sow fed basal diet with silymarin 40 g/d from late gestation to lactation.

Figure 7

Heat map of the Spearman r correlations between gut microbiota and plasma cytokines in lactation sow at the phylum level (A) and the genus level (B). n = 10. * is significantly different (p < 0.05). ** are significantly different (p < 0.01) (following the Spearman correlation analysis).