Effects of silymarin supplementation during late gestation on reproductive performance, haematological parameters, antioxidant status, and gut microbiota in sows

This study aimed to evaluate the effects of silymarin supplementation during late gestation on reproductive performance, haematological parameters, antioxidant capacity, and gut microbiota composition in sows. Twenty parity-4 crossbred sows (Landrace × Yorkshire) were enrolled and randomly allocated in parity blocks to either a control group (CG; n = 10, basal diet) or a silymarin-supplemented group (SIL; n = 10, basal diet + 200 mg/kg silymarin). The experimental period extended from day 85 of gestation to the completion of farrowing. The results demonstrated that dietary silymarin significantly reduced the number of stillbirths (P < 0.05), without exerting a significant effect on the total number and proportion of live-born piglets (P > 0.05). No notable differences were observed in haematological parameters between the two groups (P > 0.05). However, catalase (CAT) activity and total antioxidant capacity (T-AOC) were significantly elevated in the silymarin group (P < 0.05), and superoxide dismutase (SOD) showed a tendency to increase (P = 0.078). High-throughput 16S rRNA sequencing revealed 1 671 unique feature sequences in the silymarin group and 1 073 in the control group, with 1 600 sequences shared between the two groups. A trend towards increased dominance was observed in the silymarin group (P = 0.082), while both the Shannon and Simpson indices tended to decline (P = 0.087; P = 0.082), suggesting a possible reduction in microbial diversity. Principal coordinate analysis (PCoA) of β-diversity revealed significant structural differences in gut microbiota between the two groups. SIMPER analysis identified Terrisporobacter as the principal genus contributing to these differences. In conclusion, silymarin supplementation during late gestation may enhance reproductive outcomes in sows, potentially through modulation of gut microbial composition and enhancement of systemic antioxidant status.