Effects of vitamin C on production performance, rumen fermentation, and blood antioxidant indices in heat-stressed Holstein dairy cows

< 0.05). In conclusion, dietary Vitamin C-2-phosphate effectively improves rumen fermentation, alleviates oxidative stress, enhances lactation performance, and promotes mammary gland health in heat-stressed Holstein cows. The 40 g/head/d dosage yielded the most favorable effects among the tested levels. Future studies should determine the optimal Vitamin C-2-phosphate inclusion levels under different heat stress intensities and physiological stages of production, and explore its synergistic effects with other functional additives.