Effects of low-protein diets supplemented with antioxidants on histopathology of testis and testosterone and performance of male Japanese quail ( Coturnix coturnix japonica )

ABSTRACT The present study sought to examine the effects of low-protein diets supplemented with natural and synthetic antioxidants on reproductive traits and performance of male Japanese quail. A total of 144 one-day-old quail chicks were randomly assigned to receive four different treatments, including a control diet (a basal diet) without antioxidant supplementation, low-protein diet without antioxidant supplementation, low-protein diet supplemented with the E-selenium antioxidant (a combination of vitamin E and selenium), and low-protein diet supplemented with the antioxidant Loxidan (a combination of propyl galat, ethoxyquin, and citric acid). Throughout the study, feed and water were provided ad libitum from one to 45 days of age. Performance values were calculated at the end of the experimental period. Blood samples were collected from the wing vein of six male birds randomly selected from each treatment group. Subsequently, blood samples were used to measure serum testosterone levels by ELISA. A total of 36 slides were prepared from testes of 12 adult quail for histological studies. Results from this study showed that there was a significant increase in blood testosterone levels of quail fed the antioxidant Loxidan. An increased number of spermatogonia was found in quail fed both antioxidants. In addition, a significant increase was found in the number of spermatid cells in quail fed a low-protein diet with antioxidants. Surprisingly, spermatozoa cells showed a significant elevation in quail fed antioxidants as compared with those fed low-protein diets. Interestingly, a significant increase was observed in the final body weight of the quail fed antioxidants. Therefore, it can be deduced that antioxidant intake not only can improve reproductive indices, such as testosterone levels and testicular tissue in Japanese quail, but is also useful for performance of quail fed low-protein diets.