Dietary glycine supplementation alleviates transportation-induced stress in common carp, Cyprinus carpio

Abstract

Fish transportation is a stressful event in aquaculture industry, which causes crowding stress, oxidative stress, hypoxia, and water pollution stress. Therefore, it is necessary to work on the methods for mitigation of such stresses. Glycine has been known for its roles in the antioxidant system and ammonia detoxification in fish. Therefore, the present study aimed at assessing the effects of dietary glycine on growth performance, stress and antioxidant responses of common carp, Cyprinus carpio, during transportation. The fish were fed diets supplemented with 0 (G0), 2.5 (G2.5), 5 (G5), and 10 (G10) g/kg glycine for 8 weeks, then transported in plastic bags for 6 h. According to the results, dietary glycine induced no significant changes in growth performance of the fish. Plasma ammonia decreased, but plasma urea increased by dietary glycine supplementation before and/or after transportation. Dietary glycine significantly increased plasma glutathione (GSH) levels before transportation and suppressed GSH decrease after transportation, particularly at 5 and 10 g/kg. Glycine supplementation significantly suppressed plasma cortisol, glucose, superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase, and malondialdehyde after transportation, particularly at 5 and 10 g/kg. The present study demonstrates that glycine is a useful dietary supplement for common carp, as it improves antioxidant capacity and helps the fish during transportation. Such effects can be achieved by dietary glycine supplementation at 5 g/kg in common carp.