Abstract: To investigate the effects of dietary vitamin C polyphosphate on anti-heat stress ability in mice,the 48 male mice of 3-4 weeks old with an initial body weight of 16-29 g were divided into four groups one control group ? and three experimented groups (Ⅰ,Ⅱ and Ⅲ),which were fed with 35% vitamin C polyphosphate supplementation at the dosages of 0,500,2 500 and 5 000 mg/kg diets,respectively.After feeding 4 weeks,half of mice per group were killed,the other halves of the mice were treated with 35±1℃ for 24 h.Their livers were collected,and the levels of lipid peroxides (LPO) and activity of the superoxide dismutases (SOD) were determined with thiobarbituric acid reaction and nitrite-form method,respectively;and the activities of catalase (CAT) and glutathione peroxidase (GSH-Px) with colorimetry method.The results showed:liver LPO levels in heat stressed C and Ⅰ significantly increased,while Ⅱ and Ⅲ had no significant changes compared with non-heat stressed those.The activities of SOD and GSH-Px in stressed C significantly decreased,while the other three groups had no significant difference compared with non-heat stressed those.The activities of SOD in Ⅱ and Ⅲ were significantly higher than those of C and Ⅰ,and the activity of GSH-Px in Ⅲ was higher than those of the other three groups in stressed mice.The activity of CAT in stressed C and Ⅰ notably reduced,but Ⅱ and Ⅲ had no significant changes compared with non-stressed those.In stressed mice,the activities of CAT in Ⅱ and Ⅲ were higher than those of both C and Ⅰ.These results suggested that heat stress increased liver LPO level and depressed antioxidase activity in mice,while vitamin C polyphosphate alleviated the adverse effects caused by heat stress.