Effect of dietary conjugated linoleic acid (CLA) on growth performance, body composition and hepatic intermediary metabolism in juvenile yellow catfish Pelteobagrus fulvidraco

Abstract

The present study was conducted to determine the effect of dietary conjugated linoleic acid (CLA) on growth performance, body composition and hepatic intermediary metabolism in juvenile yellow catfish Pelteobagrus fulvidraco (initial body weight: 1.87 ± 0.04 g, mean ± SD). The five isonitrogenous (35% crude protein) experimental diets were formulated to contain graded CLA levels of 0 (control), 0.5, 1, 1.5 and 2%, respectively. Three replicated groups of fish were fed to satiation, twice a day, over a period of 8 weeks with CLA oil, containing mainly the bioactive cis-9, trans-11 and trans-10, and cis-12 isomers. The increase of dietary CLA levels reduced growth performance, feed conversion rate (FCR), condition factor, hepatosomatic index and viscerosomatic index of yellow catfish. Increasing dietary CLA levels significantly reduced lipid contents in the whole body and liver. The dietary inclusion of CLA modified total percentages of the main groups of fatty acids. Increasing saturated fatty acid (SFA) content and reduced mono-unsaturated fatty acid (MUFA) contents in the whole body were observed with increasing dietary CLA inclusion. A gradual reduction of 16:1 and 18:1 fatty acids was depicted in the whole body with increasing CLA levels. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) profiles showed no significant differences among the treatments. Total polyunsaturated fatty acids (PUFA) tended to increase with increasing dietary CLA levels. Dietary CLA supplementation resulted in a significant increase of the trans-10, cis-12 and cis-9, and trans-11 CLA isomers in the whole body, and also significantly influenced several hepatic enzymatic activities, such as succinate dehydrogenase (SDH), lactate dehydrogenase (LDH), malic dehydrogenase (MDH), lipoprotein lipase (LPL) and hepatic lipase (HL) activities. These indicate that despite promoting the CLA and PUFA deposition in the whole body, dietary CLA supplementation should be carefully evaluated in intensive yellow catfish farming as it reduces growth performance and feed utilization.