The effect of aerobic exercise training on growth performance, innate immune response and disease resistance in juvenile Schizothorax prenanti

Aerobic exercise training may improve the growth and disease resistance of fish. To examine the effect of aerobic exercise training on growth performance, innate immune responses and disease resistance in juvenile Schizothorax prenanti (13.79 ± 0.15 g), fish were subjected to aerobic training at different water velocities, including the control (0.33) and 1, 2 and 4 body length (bl) s− 1, for 8 weeks at 19 ± 2 °C. The growth parameters, whole-body composition, innate immune response and disease resistance against Aeromonas hydrophila of the experimental fish were investigated. The results indicated that aerobic exercise training induced a significant increase in feed intake (FI) compared with the control group, while feed efficiency (FE) of the 4 bl s− 1 group was significantly lower than those of the other three groups (P < 0.05). The 1 and 2 bl s− 1 training group showed a significantly higher specific growth rate (SGR) than the control group and the 4 bl s− 1 training group (P < 0.05). The 2 bl s− 1 training group had significantly higher whole-body fat and protein contents (P < 0.05) while the 4 bl s− 1 training group had the lowest fat contents (P < 0.05). Higher lysozyme activities and phagocytic indices were observed in the 1 and 2 bl s− 1 training groups after 4 and 8 weeks (P < 0.05) and higher respiratory burst (RB) values were observed after 8 weeks (P < 0.05). After 4 and 8 weeks, the 4 bl s− 1 training group had the lowest lysozyme, phagocytic index and respiratory burst (RB) value among all the experimental groups. The challenge test with A. hydrophila revealed that fish in the 2 and 1 bl s− 1 training group showed higher cumulative survival (75.0% and 66.7%, respectively) than fish in the control and the 4 bl s− 1 training group (51.7% and 45.0%, respectively) (P < 0.05). Quadratic regression analysis on SGR and lysozyme activity indicated that the recommended optimum exercise training intensity for juvenile S. prenanti was 2.29 and 1.80 bl s− 1, respectively. The result suggested that aerobic exercise training under approximately 2.0 bl s− 1 could improve growth performance, innate immune response and robustness of juvenile S. prenanti.