Dietary energy requirement for cachara juveniles, Pseudoplatystoma reticulatum

Abstract

Cachara, Pseudoplatystoma reticulatum, is a carnivorous freshwater catfish with high commercial value in Brazil, but the lack of knowledge about its nutritional requirements hinders the formulation of diets that allow maximum performance. Since dietary energy requirement of cachara is unknown, we tested increasing levels of gross energy (3.696, 4.049, 4.343, 4.828 and 5.232 kcal kg^-1) with isonitrogenous (49% crude protein) diets for juvenile cachara. Groups of nine juveniles (84.43 ± 13.59 g) were stocked into 15 experimental units and fed the experimental diets for 90 days. A polynomial regression analysis revealed a quadratic effect of increasing the concentration of dietary gross energy on weight gain, daily weight gain, specific growth rate, feed conversion, feed efficiency, feed consumption and apparent net protein retention. On the other hand, body fat increased linearly as dietary gross energy increased, contrary to moisture. The digestibility of protein, dry matter and energy did not vary significantly among diets containing 4,049; 4,343 and 4,828 kcal kg^-1 gross energy. Therefore, for a maximum daily weight gain, the estimated energy requirement for juvenile cachara of 84.43 g to 240 g is 3,497 kcal kg^-1 digestible energy, equivalent to a 8.08 kcal g^-1 digestible energy : digestible protein ratio.