Effects of dietary curcumin supplementation on growth performance, intestinal digestive enzyme activities and antioxidant capacity of crucian carp Carassius auratus

•The diet supplemented with curcumin improved fish growth performance.•The dietary curcumin promoted digestive and intestinal antioxidative ability in fish.•The mRNA expressions of digestive and antioxidative genes were up-regulated in response to dietary curcumin.

A 105-day feeding trial was carried out to investigate the effects of dietary curcumin (CM) supplementation on growth performance, digestive enzyme activities, and intestinal antioxidant capacity of crucian carp (Carassius auratus). A total of 585 crucian carp with average initial weight of 76.3 ± 0.10 g were fed three diets supplemented with 0 (basal group), 1, or 5 g kg− 1 CM. Fish fed the diet supplemented with 5 g kg− 1 CM showed significantly higher final body weight (FW), percent weight gain (PWG), and feed efficiency (FE) compares to those fed the basal or 1 g kg− 1 CM diet (P < 0.05). Feed intake and body composition were not significantly different among dietary groups (P > 0.05). The hepatopancreas weight, hepatopancreas protein content, intestinal weight, intestinal somatic index, intestine protein content, trypsin and lipase activities in hepatopancreas and intestine, amylase activity in hepatopancreas, Na+, K+-ATPase (NKA), alkaline phosphatase (AKP), gamma-glutamyl transpeptidase (γ-GT), and creatine kinase (CK) activities in intestine were significantly increased with dietary CM supplementation at 5 g kg− 1 (P < 0.05). Fish fed the 5 g kg− 1 CM diet showed significantly lower malondialdehyde and protein carbonyl contents in the intestine (P < 0.05). Superoxide anion and hydroxy radical scavenging ability, glutathione reducase (GR), catalase (CAT), total superoxide dismutase (T-SOD), glutathione peroxidase (GPx), and glutathione-S-transferase (GST) activities, and glutathione (GSH) content in the intestine were significantly increased with increased CM. The relative mRNA expressions of trypsin, lipase, NKA, AKP, γ-GT, CK, SOD1, CAT, GPx, GST, and GR in intestine were significantly up-regulated by dietary CM supplementation at 5 g kg− 1. These results suggested that dietary CM supplementation increased intestinal antioxidant capacity, digestive and absorptive ability, and promoted fish growth.