Effects of temperature and feeding rate on postprandial metabolic response in juvenile Percocypris pingi

The marked increase in the metabolic rate that occurs following feeding is commonly referred to as specific dynamic action (SDA). Previous studies on SDA in animals have found that the meal type, temperature, body size, feeding frequency, fasting and feeding rate all have significant effects on SDA. The study of postprandial metabolic response in Percocypris pingi has not been reported. To investigate the effects of temperature and feeding rate on postprandial metabolic traits in juvenile P. pingi, the experimental fish body weight: (38.35±0.49) g, body length: (14.22±0.10) cm were fed with loach (Misgurnus anguillicaudatus) (feeding rates: 1%, 2%, 4% body mass at 15 °C; 1%, 2%, 4% and 6% body mass at 25 °C) for 4 weeks as diet acclimation at 15 °C and 25 °C in indoor recirculating aquaculture systems. After that, the oxygen consumption rate was detected and parameters related to postprandial metabolic response were calculated. Results showed that at the same feeding rate, resting metabolic rate, peak metabolic rate, total energy expenditure on SDA and SDA coefficient of 25 °C acclimation group were significantly higher than those of 15 °C acclimation group. The SDA duration of 25 °C acclimation group at 2% and 4% feeding rate was significantly shorter than that of 15 °C acclimation group. At the 25 °C, fish of higher feeding rates (4% and 6%) presented significantly higher peak metabolic rate, factorial metabolic scope, SDA duration and total energy expenditure on SDA than those of lower feeding rates (1% and 2%) at 25 °C, and times to peak metabolic rate of 4% and 6% feeding rates were significantly earlier than that of 1% and 2% feeding rates as well. However, the SDA coefficient showed an opposite situation: higher feeding rate presented significantly lower values. At the 15 °C, peak metabolic rate, factorial metabolic scope, SDA duration and energy expended on SDA of 4% feeding rate group were significantly higher than those of 1% and 2% feeding rates. Nevertheless, no significant difference in the time to peak metabolic rate and the SDA coefficient among all feeding rates were observed at 15 °C. All the above information suggested that the water temperature of 25 °C is more beneficial to the rapid food digestion and absorption by juvenile P. pingi; and the fish may meet the increased energy demand during digestive process by means of increasing peak metabolic rate and prolonging SDA duration with the increase of feeding rate. The results of this study may provide important reference data for the breeding practice and species protection of P. pingi.