LAUSR

The purpose of this study was to assess the effect of different carbohydrate and lipid (CHO/L) ratios on the performance and energy metabolism of hybrid catfish (♂Pseudoplatystoma corruscans × ♀ Pseudoplatystoma fasciatum). One hundred and sixty-eight fish (104.9±16.5 g BW) were distributed into 24 100-L tanks. The experiment was performed using a randomised block design with four CHO/L ratios (0.45, 1.00, 1.66 and 2.85) and six replications. Growth performance, protein content, glucose and triglycerides in plasma, muscle and liver, and the hepatic activity of the malic and glucose-6-phosphate dehydrogenase (G6PD) enzymes were measured after 60 feeding days. No significant differences were observed in growth performance, protein and triglycerides of plasma and muscle, hepatic protein or malic enzyme activity. CHO/L: 2.85 provided the highest plasma and liver glucose, while CHO/L: 0.45 showed high liver triglycerides. A linear effect was found for the hepatic activity of G6PD and dietary starch levels (R2=0.93). The hepatic activity of G6PD was greater in CHO/L=2.85 than for CHO/L: 0.45. In conclusion, the limit of dietary starch inclusion and lipids were 15% and 9.00%, respectively (CHO/L: 1.66), and this level did not affect the energy metabolism of the juvenile hybrid catfish.