Effect of feeding and fasting on excess post-exercise oxygen consumption in juvenile southern catfish (Silurus meridionalis Chen)

The impact of feeding (fed to satiation, 13.85% body mass) on excess post-exercise oxygen consumption (EPOC, chasing for 2.5 min) was investigated in juvenile southern catfish (Silurus meridionalis Chen) (38.62–57.55 g) at 25. Cutlets of freshly killed loach species without viscera, head and tail were used as the test meal, and oxygen consumption (VO2) was adjusted to a standard body mass of 1 kg using a mass exponent of 0.75. Resting VO2 increased significantly above fasting levels (49.89 versus 148.25 mg O2 h− 1) in 12 h postprandial catfish. VO2 and ventilation frequency (Vf) both increased immediately after exhaustive exercise and slowly returned to pre-exercise values in all experimental groups. The times taken for post-exercise VO2 to return to the pre-exercise value were 20, 25 and 30 min in 12 h, 60 h and 120 h postprandial catfish, respectively. Peak VO2 levels were 257.36 ± 6.06, 219.32 ± 6.32 and 200.91 ± 5.50 mg O2 h− 1 in 12 h, 60 h and 120 h postprandial catfish and EPOC values were 13.85 ± 4.50, 27.24 ± 3.15 and 41.91 ± 3.02 mg O2 in 12 h, 60 h and 120 h postprandial southern catfish, respectively. There were significant differences in both EPOC and peak VO2 during the post-exercise recovery process among three experimental groups (p < 0.05). These results showed that: (1) neither digestive nor exhaustive exercise could elicit maximal VO2 in southern catfish, (2) both the digestive process and exercise (also the post-exercise recovery process) were curtailed under postprandial exercise, (3) the change of Vf was smaller than that of VO2 during the exhaustive exercise recovery process, (4) for a similar increment in VO2, the change in Vf was larger during the post-exercise process than during the digestive process.