Supplementation of Natural Antioxidants to Reduced Crude Protein Diets for Japanese Quails Exposed to Heat Stress

The study aimed at comparing the effects of the supplementation of natural antioxidant sources to a reduced crude protein diet on the performance, carcass traits, blood parameters, liver antioxidant enzyme activities and meat lipid peroxidation of Japanese quails exposed to heat stress. A total of 640 14-day-old male Japanese quails were exposed to two different temperature treatments (TT): thermoneutral (TN) or heat stress (HS)and were fed five different dietary treatments (DTs). A normal-protein diet (SCP) was formulated according to the National Research Council (24% CP). The reduced crude protein diet (RCP) was formulated to contain 3% less protein than that of the SCP diet. Three additional diets were prepared by supplementing the RCP with200 mg/kg of alpha-tocopherol acetate (RCP+TA200), pomegranate peel extract (RCP+PPE200) or apple peel extract (RCP+APE200). HS significantly deteriorated the growth performance of quails throughout the experiment. Quails fed the SCP and RCP+PPE200 presented higher hematocrit values. Feeding the RCP+TA200 and RCP+PPE200 diets reduced the blood heterophil/lymphocyte (H/L) ratio compared with the other diets. Quails fed the SCP, RCP+TA200, RCP+PPE200 and RCP+APE200 diets presented higher liver catalase and glutathione peroxidase activities, plasma uric acid level, and lower meat malondialdehyde value at 7days of age compared with those fed the RCP diet. In conclusion, the results show that the extracts of pomegranate peel and apple peel can be used as alternative natural antioxidant sources to vitamin E in the diets of Japanese quails exposed to heat stress and fed a reduced crude protein diet.