Effects of intermittent cold stimulation on antioxidant capacity and mRNA expression in broilers

In this study, the effects of intermittent cold stress on the antioxidant capacity and antioxidant-related gene expression in broilers were examined. AA broilers were randomly divided into four groups. The control group was kept in a normal thermal environment. Treatment groups I, II, and III were maintained at 3 °C, 5 °C, and 7 °C lower than the control group, respectively, for 6-h periods at intervals of 2 days from 22 days of age to 42 days of age. At 35 days of age, the antioxidant indexes of group I and the control group were higher than those of groups II and III (P < 0.05). At 42 days of age, the activities of TAOC and GSH-Px were higher in group I than in the control group, group II and III. The activities of TSOD and CAT were higher in group I than in groups II and III (P < 0.05). The TAOC activity of all treatment groups increased from 35 days of age to 42 days of age. (P < 0.05). The GSH-Px activity of group I and the CAT activity of group III increased from 35 days of age to 42 days of age (P < 0.05). The GSH-Px activity of group II and the control group and the CAT activity of group II decreased from 35 days of age to 42 days of age (P < 0.05). At 35 days of age, mRNA expression levels of SOD were lower in all treatment groups than in the control group (P < 0.05). At 42 days of age, mRNA expression levels of SOD were higher in group I and the control group than in groups II and III (P < 0.05). At 35 days of age, GSH-PX expression was lower in groups II and III than in the control group and group I (P < 0.05), but did not differ between group I and the control group (P > 0.05). At 42 days of age, GSH-Px expression was higher in the control than in groups II and III (P < 0.05) and higher in group I than in the control (P < 0.05). SOD expression in all treatment groups increased from 35 days of age to 42 days of age (P < 0.05). GSH-Px expression in the control group and groups II and III decreased from 35 days of age to 42 days of age (P < 0.05). The influence of intermittent cold treatment on SOD and GSH-Px expression was consistent with SOD and GSH-Px activities. These results suggested that the influence of cold on antioxidant capacity is related to gene transcription regulation.