Effect of resveratrol supplementation on antioxidant capacity, inflammatory traits and microbial diversity in Holstein heifer calves during weaning transition.

The study evaluated the potential of resveratrol (RES) supplementation to mitigate weaning stress in Holstein calves by examining its effects on antioxidant capacity, inflammatory responses, and rumen microbiota composition during this critical developmental transition. Twenty 39-day-old Holstein heifer calves were randomly allocated to two groups: a control (CON, diet with no resveratrol) and a resveratrol-supplemented group (RES, diet plus 350 mg resveratrol/kg body weight/day). The trial comprised a 7-day adaptation period and a 28-day experimental period, with weaning at 60 days of age (day 0). Blood samples were collected on days − 7, +1, + 7, and + 14, and rumen fluid samples were obtained on days − 7 and + 7. The RES supplementation group demonstrated significantly enhanced antioxidant capacity, particularly evidenced by increased T-SOD activity, along with a marked reduction in diarrhea incidence: a 36.5% decrease in mild diarrhea and a 48.6% decrease in profuse diarrhea. Moreover, RES supplementation effectively suppressed inflammatory responses, as shown by decreased IL-6 levels. Additionally, rumen microbial richness indices were substantially improved in RES-treated calves, with notable enrichment of beneficial bacterial genera including Shuttleworthia and Rikenellaceae_RC9_gut_group. Furthermore, PICRUSt2 analysis was employed to predict the functional potentials of these rumen microbiota alterations. Dietary RES supplementation significantly enhanced antioxidant capacity, attenuated inflammatory responses, and improved rumen microbial richness indices in Holstein heifer calves during the weaning transition period.