title: The effect of aerobic exercise and starvation on growth performance and postprandial metabolic response in juvenile southern catfish (Silurus meridionalis).
abstract: To investigate the effects of aerobic exercise and starvation on growth performance, postprandial metabolic response and their interaction in a sedentary fish species, either satiation-fed or starved juvenile southern catfish (Silurus meridionalis) were exercised at 25 °C under three water velocities, i.e., nearly still water (control), 1 body length (bl) s(-1) and 2 bl s(-1), for eight weeks. Then, the feed intake (FI), food conversion efficiency (FCE), specific growth rate (SGR), morphological parameters, resting ṀO2 (ṀO2rest) and postprandial ṀO2 responses of the experimental fish were measured. Exercise at a low velocity (1 bl s(-1)) showed no effect on any growth performance parameter, whereas exercise at a high velocity (2 bl s(-1)) exhibited higher FI but similar SGR due to the extra energy expenditure from swimming and consequent decreased FCE. Starvation led to a significant body mass loss, whereas the effect intensified in both exercise groups. Exercise resulted in improved cardio-respiratory capacity, as indicated by increased gill and heart indexes, whereas it exhibited no effect on resting and postprandial metabolism in S. meridionalis. The starved fish displayed significantly larger heart, gill and digestive tract indexes compared with the feeding fish, suggesting selective maintenance of cardio-respiratory and digestive function in this fish species during starvation. However, starved fish still exhibited impaired digestive performance, as evidenced by the prolonged duration and low postprandial metabolic increase, and this effect was further exacerbated in both the 1 and 2 bl s(-1) exercise groups. These data suggest the following: (1) aerobic exercise produced no improvement in growth performance but may have led to the impairment of growth under insufficient food conditions; (2) the mass of different organs and tissues responded differently to aerobic exercise and starvation due to the different physiological roles they play; and (3) aerobic exercise had no effect on the postprandial metabolic response under a "normal feeding" situation, whereas it may have resulted in the impairment of the digestive capacity when food availability was low due to the competition of energy and oxygen under unfavorable conditions in juvenile S. meridionalis.
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Education Ministry), Key Laboratory of Aquatic Science of Chongqing, School of Life Sciences, Southwest University, Chongqing 400715, China; Laboratory of Evolutionary Physiology and Behavior, Chongqing Key Laboratory of Animal Biology, Chongqing Normal University, Chongqing 400047, China.
authors.forename: Xiu-Ming
authors.initials: XM
authors.lastname: Li
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Education Ministry), Key Laboratory of Aquatic Science of Chongqing, School of Life Sciences, Southwest University, Chongqing 400715, China.
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.affiliation: Fisheries Technology Extension Station in Chongqing, Chongqing 400020, China.
authors.forename: Jian-Ming
authors.initials: JM
authors.lastname: Yuan
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Education Ministry), Key Laboratory of Aquatic Science of Chongqing, School of Life Sciences, Southwest University, Chongqing 400715, China.
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Xiao
authors.affiliation: Laboratory of Evolutionary Physiology and Behavior, Chongqing Key Laboratory of Animal Biology, Chongqing Normal University, Chongqing 400047, China.
authors.forename: Shi-Jian
authors.initials: SJ
authors.lastname: Fu
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Education Ministry), Key Laboratory of Aquatic Science of Chongqing, School of Life Sciences, Southwest University, Chongqing 400715, China. Electronic address: zhangyg@swu.edu.cn.
authors.forename: Yao-Guang
authors.initials: YG
authors.lastname: Zhang
mesh_terms: D000818:Animals; D002397:Catfishes / Q000378:metabolism / Q000502:physiology*; D004063:Digestion / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology; D041981:Gastrointestinal Tract / Q000378:metabolism / Q000473:pathology; D010100:Oxygen / Q000378:metabolism; D010101:Oxygen Consumption; D010805:Physical Conditioning, Animal / Q000502:physiology*; D019518:Postprandial Period / Q000502:physiology*; D013217:Starvation / Q000378:metabolism / Q000503:physiopathology*; D013550:Swimming / Q000502:physiology
chemical_list: D010100:Oxygen
keywords: Aerobic exercise; Growth; Silurus meridionalis; Specific dynamic action; Starvation