Effect of different carbohydrate-to-lipid ratios elicits growth, feed utilization, lipid deposition and lipogenic enzyme activity in striped catfish (Pangasianodon hypophthalmus, Sauvage, ۱۸۷۸) fingerlings

This study evaluated the effects of diets containing various carbohydrate-to-lipid (CHO L-۱) ratios on growth performance, nutrient utilization body indices and hepatic lipogenic enzyme (malic enzyme, ۶-phosphogluconate dehydrogenase and fatty acid synthase) activities. Triplicate groups of Pangasianodon hypophthalmus fingerlings were fed eight isoenergetic and isonitrogenous diets with different carbohydrate-to-lipid ratios (۰.۵۱, ۰.۷۹, ۱.۱۲, ۱.۷۹, ۲.۴۱, ۳.۲۴, ۴.۴۳ and ۷.۶۲). Higher body fat deposition and lower growth performance were observed in P. hypophthalmus fingerlings fed with high-lipid diet than those fed with high-carbohydrate diet. The fish fed the diet with ۷.۶۲ CHO L-۱ ratio exhibited significantly (p<۰.۰۵) higher hepatosomatic index compared to those fed higher lipid diets (۰.۵۱ and ۰.۷۹). High dietary carbohydrate level significantly increased (p<۰.۰۵) the activities of malic, ۶-phosphogluconate dehydrogenase and fatty acid synthase enzyme. Based on the second-order polynomial regression analysis of weight gain, the optimal dietary carbohydrate and lipid contents for P. hypophthalmus fingerling were ۳۰۴ and ۱۰۳ g kg−۱, respectively, which correspond to a dietary CHO L-۱ ratio of ۲.۹۵.

Keywords:

Striped catfish , Carbohydrate-to-lipid ratio , Lipogenesis , Fat deposition