Effects of Tea Polyphenol and L-theanine on Growth Performance and Antioxidant Performance of Egg-laying Chickens under Heat Stress

In order to investigate the effects of tea polyphenols (TP) and L-theanine on growth performance and antioxidant performance of egg-laying chickens under heat stress,single factor design was adopted.180 one-day old chickens were randomly assigned to six groups for three replicates (10 chicks for each). Group 1 was the control group,was fed on a basal diet;groups 2 to 6 were the treatment groups,were fed with 400 mg/kg TP, 200 mg/kg L-theanine, 200 mg/kg TP and 200 mg/kg L-theanine,400 mg/kg TP and 200 mg/kg L-theanine, 600 mg/kg TP and 200 mg/kg L-theanine in the basal diet. The trial period was 28 d. The results indicated that TP could decrease feed gain significantly (P<0.05),L-theanine added alone or combined with TP had no significant effects on growth performance (P>0.05). TP could decrease the tissues and organs's content of MDA significantly (P<0.05),and enhance the activities of GSH-Px and CAT significantly (P<0.05).L-theanine could improve the activity of CAT significantly (P<0.05),and decreased the tissues and organs's content of MDA in different degrees.TP combined with L-theanine, the antioxidant performance was out of step with the addition of TP. When 400 mg/kg TP and 200 mg/kg L-theanine were added,the T-SOD and GSH-Px activities of liver significantly decreased (P<0.05),the MDA content increased significantly (P<0.05). Under heat stress,the addition of 200 mg/kg TP and 200 mg/kg L-theanine is the most appropriate antioxidant effect.