摘要Background Heat stress has severe negative consequences on performance and health of pigs,leading to significant economic losses.The objective of this study was to investigate the effects of supplemental vitamin E and a botanical extract in feed or drinking water on growth performance,intestinal health,and oxidative and immune status in grow-ing pigs housed under heat stress conditions.Methods Duplicate experiments were conducted,each using 64 crossbred pigs with an initial body weight of 50.7±3.8 and 43.9±3.6 kg and age of 13-weekand 12-week,respectively.Pigs(n=128)were housed individually and assigned within weight blocks and sex to a 2×4 factorial arrangement consisting of 2 environments(thermo-neutral(21.2 ℃)or heat-stressed(30.9 ℃))and 4 supplementation treatments(control diet;control+100 IU/L of D-α-tocopherol in water;control+200 IU/kg of DL-α-tocopheryl-acetate in feed;or control+400 mg/kg of a botanical extract in feed).Results Heat stress for 28 d reduced(P≤ 0.001)final body weight,average daily gain,and average daily feed intake(-7.4 kg,-26.7％,and-25.4％,respectively)but no effects of supplementation were detected(P＞0.05).Serum vitamin E increased(P＜0.001)with vitamin E supplementation in water and in feed(1.64 vs.3.59 and 1.64 vs.3.24),but not for the botanical extract(1.64 vs.1.67 mg/kg)and was greater when supplemented in water vs.feed(P=0.002).Liver vitamin E increased(P＜0.001)with vitamin E supplementations in water(3.9 vs.31.8)and feed(3.9 vs.18.0),but not with the botanical extract(3.9 vs.4.9 mg/kg).Serum malondialdehyde was reduced with heat stress on d 2,but increased on d 28(interaction,P＜0.001),and was greater(P＜0.05)for antioxidant supplementation compared to control.Cellular proliferation was reduced(P=0.037)in the jejunum under heat stress,but increased in the ileum when vitamin E was supplemented in feed and water under heat stress(interaction,P=0.04).Tumor necrosis factor-α in jejunum and ileum mucosa decreased by heat stress(P＜0.05)and was reduced by vitamin E sup-plementations under heat stress(interaction,P＜0.001).Conclusions The addition of the antioxidants in feed or in drinking water did not alleviate the negative impact of heat stress on feed intake and growth rate of growing pigs.