Effects of resveratrol supplementation on performance and metabolic adaptations in heat-stressed Holstein cows during early lactation

This study investigated the effects of resveratrol (RSV) supplementation on performance and metabolic responses of heat-stressed, early lactation cows. Eighteen cows (BW = 640.8 ± 29.4 kg, parity = 2.0, average daily milk yield = 44.4 ± 2.0 kg and days in milk (DIM) = 39.8 ± 6.5 d; mean ± SD) were randomly assigned to one of three treatment groups: (1) control (CON; no RSV supplementation), (2) RSV-4 (4 mg RSV/kg BW per d) or (3) RSV-8 (8 mg RSV/kg BW per d). Results demonstrated that RSV supplementation, particularly at 8 mg/kg, significantly improved DMI and milk yield, with increases of 0.8 kg/d and 2.9 kg/d, respectively (P < 0.05). The RSV-8 treatment also significantly reduced rectal and vaginal temperatures compared to both the CON and RSV-4 groups (P < 0.01), while the RSV-4 treatment resulted in a higher respiratory rate (RR) than both the CON and RSV-8 groups (P < 0.01). In addition, serum metabolic parameters showed that RSV-8 and RSV-4 supplementation significantly increased serum aspartate aminotransferase activity and NEFA levels, respectively, compared to the CON group (P < 0.05). RSV supplementation at both levels led to a significant increase in serum insulin levels. Antioxidant analysis showed that RSV supplementation increased serum malondialdehyde levels, especially in the RSV-4 group (P < 0.05). In general, these results indicate that RSV supplementation can have a positive effect on feed intake and lactation performance in heat-stressed Holstein dairy cows in early lactation.