Effects of dietary resveratrol supplementation on digestive enzymes activities and serum biochemistry of rainbow trout (Oncorhynchus mykiss)

The effects of resveratrol as an anti-oxidant in improving growth and health have been shown in several experiments. This study aimed to evaluate the effects of different dietary resveratrol inclusion levels on digestive enzymes activity and serum biochemistry of rainbow trout (Oncorhynchus mykiss). Accordingly, 225 juvenile rainbow trout with an average body weight of 10.00 ± 1.50 g were stocked in nine experimental units. The study was performed as a completely randomized design including three dietary levels of resveratrol as follows: 0.00, 400 and 800 mg kg^-1 feed. During the experiment, fish were fed based on their respective body weight using standard feeding tables at three feeding times for 8 weeks. Nine fish were randomly selected from each treatment at the end of the 4^th and 8^th weeks of the experiment. Results revealed that supplementing 800 mg kg^-1 feed resveratrol significantly increased lipase activity (31.40 ± 0.32 U mg^-1 protein) compared to the control group (29.92 ± 0.52 U mg^-1 protein) at the end of week eight. Also, at the same time, it increased serum high-density lipoprotein (123.04 ± 1.57 mg dL^-1) compared to the control group (97.055 ± 1.463 mg dL^-1). In addition, dietary supplementation of 800 mg kg^-1 feed resveratrol effectively reduced serum alanine aminotransferase, alkaline phosphatase and aspartate aminotransferase activities along with glucose, cortisol and cholesterol. In conclusion, resveratrol can be used as a suitable food supplement to improve fish health by increasing digestive enzymes activities.