Dietary non-protein energy sources: growth, digestive enzyme activities and nutrient utilization by the catfish jundiá, Rhamdia quelen

A study was conducted to evaluate the effect of different dietary carbohydrate to lipid (CHO:L) ratios on growth, digestive enzyme activities and nutrient utilization by jundiáRhamdia quelen (Quoy & Gaimard) an omnivorous catfish native to Latin America. Groups of 40 fingerlings were stocked in 24 tanks and fed eight isonitrogenous (41% crude protein) and isoenergetic (13.5 kJ g⁻¹) casein-based diets for 75 days. Diets had eight CHO:L ratios: 0.3:1, 1.0:1, 2.0:1, 3.4:1, 4.6:1, 5.3:1, 5.6:1 and 6.5:1, and were fed twice a day to apparent satiation. Increasing CHO:L ratio did not significantly affect growth performance. However, the highest apparent net protein utilization was observed in fish fed the 5.3:1 CHO:L diet. No differences were detected among fish on apparent net energy utilization. Whole body fat deposition decreased as dietary CHOL:L ratio increased (P