Response of growth performance, serum biochemical parameters, antioxidant capacity, and digestive enzyme activity to different feeding strategies in common carp (Cyprinus carpio) under high-temperature stress

The present study aimed to evaluate the effects of using different feeding strategies on the growth performance, feed efficiency, antioxidant capacity, digestive enzyme activities, and serum biochemical parameters of common carp, Cyprinus carpio for 40 days under high-temperature stress. A total of 120 fish (average initial weight 25.30 ± 1.27 g) were distributed in 12 tanks maintained in a circulating aquarium system (a water flow rate of 1 L/min). Fish were divided into four treatments: feeding every day with two meals, feeding one-day intervals with two meals, feeding two-day intervals with two meals, and feeding four-day intervals with two meals (named as T0, T1, T2, and T3, respectively). The results show that the weight gain (WG) and specific growth rate (SGR) of the T2 group were significantly higher than the other groups, while the feed conversion rate (FCR) of the T2 group was lower than in the other groups ( P < 0.05); Serum glucose (GLU) content of fish in the T2 group was significantly higher than the other groups; The liver total superoxide dismutase (T-SOD) activity of fish in the T0 group had a significantly lower value than in the T2 group ( P < 0.05); The liver malondialdehyde (MDA) content of fish in the T0 group had a significantly lower value than those others ( P < 0.05); the gut trypsin and lipase (LPS) activity of fish in the T2 group showed the highest value, while the gut amylase (AMS) activity of fish in the T0 group showed the lowest value compared to the others; the IBR index showed the lowest value in the T2 group. It can be concluded that the T2 group of fish showed the best growth performance and gut digestive enzyme activities, with reduced negative impacts during high-temperature stress. This intermittent feeding strategy improved the antioxidant status of fish. Therefore, feeding every third day is recommended as an improved feeding regime for C. carpio during periods of elevated water temperature. The results of this study further extend our understanding of how feeding strategies in C. carpio culture can be implemented rationally during summer under high temperatures, which will provide valuable information for improving aquaculture management. • T2 group showed better growth performance; • T2 group showed less physiological stress; • The feeding strategy of T2 group was the best choice under high temperature.