BACKGROUND: In order to improve the antioxidant and anti-fatigue capacities of whey protein for wider utilization, it was hydrolyzedbychymotrypsin(EC 3.4.21.1) toproducewheyprotein hydrolysate(WPH).Fractions ofWPHwith different molecular weight (MW) were separated by ultrafiltration. Kunming mice in various treatment groups were orally administered (1.5 g kg−1 body weight) whey protein isola…