Effect of corn in diets for carnivorous catfish (Lophiosilurus alexandri) on metabolic and performance parameters

The aim of this study was to evaluate the influence of dietary corn bran levels on the performance and energy metabolism of catfish (Lophiosilurus alexandri) juveniles. In total, 120 juveniles with initial average weight of 20.85 ± 2.01 g were distributed in 20 40 L aquariums in a recirculation system. These were distributed across five treatments (5, 10, 15, 20 and 25% of carbohydrate) and four replicates (aquariums), and fed for 63 days. The parameters evaluated were performance, hepatosomatic index (IHS), viscerosomatic index (VSI), intestinal morphometry, glucose, HDL, LDL, total cholesterol, triglycerides, amylase activity, glucose‐6‐phosphate dehydrogenase (G6PD) and malic enzyme activity. Different corn concentrations in diets affected performance, decreasing final weight and daily weight gain (DWG) by more than 10% (p .05). Glucose showed a linear behaviour, increasing with increasing corn bran levels. The activity of the amylase enzyme showed no significant difference between treatments (p > .05). The activity of malic enzyme and G6PD showed a linear behaviour, in which the treatment of 5% corn presented lower activity in the liver of the animals. It is therefore concluded that having a concentration of corn above 10% in the diet worsens the development of catfish juveniles.