Effects of Fructus Ligustri Lucidi supplementation on energy metabolism, immunity, and rumen microbiome in peripartum cows

The aim of this study was to evaluate the effect of Fructus Ligustri Lucidi (FLL) supplementation on energy metabolism, immunity, and the rumen microbiome in peripartum cows. Twenty healthy multiparous Holstein dairy cows were enrolled in the trial based on expected calving date, parity, and previous lactation milk yield. They were randomly assigned to either a control diet (Con; n = 10) or the control diet supplemented with 150 g/d per cow of FLL (FLL; n = 10). The trial spanned 6 wk, from 3 wk prepartum to 3 wk postpartum. Cows were milked thrice daily at 0500, 1100, and 1700 h, with milk yield and SCC recorded. Blood samples were collected from each cow at -3, -2, -1, 0, 1, 2, and 3 weeks relative to calving to evaluate the metabolic, inflammatory, and oxidative profiles. Peripheral blood neutrophils were isolated to measure reactive oxygen species (ROS), phagocytic activity, and neutrophil extracellular traps (NET). Rumen liquid was obtained via esophageal tubing at -3, 0, and 3 wk to investigate microbial biodiversity. Results indicated that FLL supplementation did not significantly affect the milk yield or SCC within 3 wk postpartum. Notably, FLL ameliorated negative energy balance from 1 wk to 3 wk, mitigated inflammation from calving day to 3 wk, and reduced oxidative stress at both -1 and 1 wk. The FLL treatment enhanced neutrophil phagocytosis from calving day to 1 wk, increased NET release at -1 wk, and reduced neutrophil ROS levels on calving day. Moreover, FLL increased rumen microbial α-diversity on calving day. At the phylum level, Firmicutes abundance was higher in the Con group on calving day compared with 3 wk pre- and postpartum, whereas Bacteroidota exhibited the opposite trend; FLL maintained stable Firmicutes and Bacteroidota abundances throughout the peripartum period. At the genus level, Prevotella abundance decreased in both groups on calving day but rebounded by 3 wk, with significantly higher Prevotella levels in the FLL group on calving day. The level 2 Kyoto Encyclopedia of Genes and Genomes pathway prediction further indicated divergent metabolic profiles: lipid metabolism pathways were less active in the FLL group than in the Con group on calving day and at 3 wk, whereas immune-related pathways were enriched in the FLL group. Energy metabolism pathway activity was higher in the FLL group on calving day but lower by 3 wk compared with the Con group. Correlation analysis indicated that rumen microbiome shifts were associated with energy metabolism, immunity, and oxidative stress. In conclusion, this study elucidates the dynamic changes in rumen microbiome during the peripartum period and highlights the beneficial effects of FLL supplementation on energy metabolism, immune function, and rumen microbial homeostasis in peripartum dairy cows.