Effects of exercise onl-carnitine and lipid metabolism in African catfish (Clarias gariepinus) fed different dietaryl-carnitine and lipid levels

Abstract

African catfish (Clarias gariepinus) were fed four isonitrogenous diets (34 % crude protein), each containing one of two lipid (100 or 180 g/kg) and twol-carnitine (15 or 1000 mg/kg) levels. After 81 d of feeding, thirty-two fish (body weight 32 g) from each dietary group were randomly selected, sixteen fish were induced to a 3-h swim (speed of 1·5 body length (BL)/s), while the other sixteen fish were kept under resting condition. Fish fed 1000 mgl-carnitine accumulated 3·5 and 5 times morel-carnitine in plasma and muscle, respectively, than fish fed the 15 mgl-carnitine. Musclel-carnitine content was significantly lower in exercised fish than in rested fish. High dietary lipid level (fish oil) led to an increase in musclen-3 PUFA content and a decrease in SFA and MUFA content. In liver, the increase in dietary lipid level resulted in an increased levels of bothn-6 andn-3 PUFA.l-carnitine supplementation significantly decreasedn-3 PUFA content. Exercise decreasedn-3 PUFA in both muscle and liver. Plasma lactate and lactate dehydrogenase, normally associated with increased glycolytic processes, were positively correlated with exercise and inversely correlated with dietaryl-carnitine level.l-carnitine supplementation reduced significantly the RQ from 0·72 to 0·63, and an interaction between dietaryl-carnitine and lipid was observed (P < 0·03). Our results indicate that an increase in fatty acids (FA) intake may promote FA oxidation, and both carnitine and exercise might influence the regulation of FA oxidation selectivity.