Effect of different carbohydrate-to-lipid ratios elicits growth, feed utilization, lipid deposition and lipogenic enzyme activity in striped catfish (Pangasianodon hypophthalmus, Sauvage, 1878) fingerlings

This study evaluated the effects of diets containing various carbohydrate-to-lipid (CHO L-1) ratios on growth performance, nutrient utilization body indices and hepatic lipogenic enzyme (malic enzyme, 6-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 (0.51, 0.79, 1.12, 1.79, 2.41, 3.24, 4.43 and 7.62). 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 7.62 CHO L-1 ratio exhibited significantly (p<0.05) higher hepatosomatic index compared to those fed higher lipid diets (0.51 and 0.79). High dietary carbohydrate level significantly increased (p<0.05) the activities of malic, 6-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 304 and 103 g kg−1, respectively, which correspond to a dietary CHO L-1 ratio of 2.95.