The Effect Of Exercise Training On The Metabolic Competition Model Between Feeding And Locomotion In Juvenile Darkbarbel Catfish (peltebagrus Vachelli Richardson) And Southern Catfish (Silurus Meridionalis Chen)

Experimental fish were carried out treatments of either training or non-training for identification of the effects of exercise training on the metabolic competition model in juvenile darkbarbel catfish (Peltebagrus vachelli Richardson) (5.58±0.04 g) and juvenile southern catfish (Silurus meridionalis Chen) (8.69±0.07 g). Trained fish were exercised at 60% Ucrit for 1 h in the experimental exercising chamber at 25.0±0.5°C. Non-trained fish were placed in the identical experimental exercising chamber for 1 h without exercising course. Training was conducted once daily at 9:00 AM for three weeks. Then trained fish were divided into two groups (Trained fed group and Trained fasting group). Freshly killed loach was introduced into the stomach (7% body mass in darkbarbel catfish and 16% body mass in southern catfish) of fish in trained fed group through a gavage protocol. A sham-feeding procedure was carried out in trained fasting groups. Similarly, non-trained fish were divided into two groups (Non-trained fed group and Non-trained fasting group). Identical gavage protocol or sham-feeding procedure as those conducted in trained fish were executed in the non-trained fish. We investigated the postprandial metabolic response, critical swimming speeding (Ucrit) and oxygen consumption rate (VO2) of both non-trained fish and the trained fish. Aims of this study are to examine the response of metabolic competition model with exercise training and to compare the differences between the two species. We hope that our study could provide practical information for protection of fish resources in the Three Gorges reservoir region.The results are:1.Darkbarbel catfish1.1 Exercise training did not produce significant differences in resting VO2 (VO2 rest) and postprandial peak VO2 (VO2 peak) compared to the non-trained groups(the average values of VO2 rest were 67.42 and 66.61 mgO2 kg-1 h-1,the values of VO2 peak were 97.59 and 102.06mgO2 kg-1 h-1), However, exercise training elicited a significant decrease in both the duration and energy expenditure of digestion when fed with similar food (P<0.05). The duration and energy expenditure of digestion were 32 h and 52.13 kJ kg-1 in non-trained fed group and were 24 h and 31.55 kJ kg-1 in trained fed group.1.2 Feeding had no significant effect on Ucrit of non-trained fish(5.93 and 6.01 BL s?1 ,respectively), while it caused a significantly lower Ucrit (6.38 BL s?1 ) than that of fasting fish(6.70 BL s?1) in trained fish(P<0.05). Training resulted in a significantly higher Ucrit in fasting fish(P<0.05). However, training had no effect on the Ucrit of post-feeding fish.1. 3 Training resulted in a significantly higher active VO2 (VO2active) in fasting fish when fish swim at Ucrit(349.4 and 289.9 mgO2 kg-1 h-1 ,respectively)(P<0.05). However, training had no effect on VO2active of post-feeding fish(370.9 and 365.2 mgO2 kg-1 h-1 respectively).2.Southern catfish2. 1 Exercise training did not produce significant differences in resting VO2 (VO2 rest) and postprandial peak VO2 (VO2 peak) compared to the non-trained groups(the average values of VO2 rest were 47.24 and 44.95 mgO2 kg-1 h-1,the values of VO2 peak were 170.97 and 165.34mgO2 kg-1 h-1), however, exercise training elicited a significant decrease in both the duration and energy expenditure of digestion when fed with similar food (P<0.05). The duration and energy expenditure of digestion were 56 h and 151.99 kJ kg-1 in non-trained fed group and were 46 h and 139.46 kJ kg-1 in trained fed group.2. 2 Feeding caused a significant lower Ucrit (2.92 BL s?1) than that of fasting fish (3.08 BL s?1) in non-trained fish, while it had no significant effect on Ucrit in trained fish (3.09 and 3.25BL s?1) (P<0.05). Training had no significant effects on Ucrit in fasting fish. However, in post-feeding fish, training resulted in a significant higher Ucrit(P<0.05).2. 3 Training had no significant effects on active VO2 (VO2active) in fasting fish when fish were forced to swim at Ucrit (248.0 and 256.4mgO2 kg-1 h-1, respectively). In post-feeding fish, training had no effect on VO2active (321.3 and 323.5mgO2 kg-1 h-1, respectively). In conclusion:1.Exercise training can change the primal metabolic model of competition in two experimental fish. The metabolic mode of competition in darkbarbel catfish changed from an additive model to a digestion-priority model after exercise training; The metabolic mode of competition in southern catfish changed from a digestion-priority model to a activity-priority model after exercise training.2.The primal metabolic model of competition of darkbarbel catfish is different to that of southern catfish. The central cardio-respiratory system of non-trained darkbarbel catfish can support the oxygen demands of both digestion and the locomotion simultaneously (additive model); The central cardio-respiratory system of non-trained southern catfish cannot support the oxygen demands of both the digestion and the locomotion simultaneously and swimming metabolism is sacrificed to sustain the digestion when feeding and locomotion are combined (digestion-prioritization model);3.Exercise training resulted in a significantly higher Ucrit and VO2active in fasting darkbarbel catfish when fish swim at Ucrit. Trained darkbarbel catfish could utilize more potential capacity of central system and, hence, improved their swimming performance during fasting. Training resulted in a significant higher Ucrit and had no effect on VO2active in post-feeding southern catfish. Training may improve the competition capacity of locomotion metabolism during digestion;4.Exercise training has significantly influence on the primal metabolic model of competition in two experimental fish. However, the effect on darkbarbel catfish is different to that on southern catfish. It may be related with the species, life habits, trophic levels, living styles and physiological structures of two experimental fish.