Nutritional evaluation of phosphorylated pumpkin seed (Cucurbita moschata) protein concentrate in silver catfish Rhamdia quelen (Quoy and Gaimard, 1824).

An 8-week feeding trial was conducted to evaluate the effect of replacing fish meal with pumpkin seed meal (PSM) or phosphorylated protein concentrate of pumpkin seed meal (PPCPS) on growth and metabolic responses of silver catfish. Five isonitrogenous and isocaloric diets were formulated. Control diet contained fish meal as the main protein source. The treatment groups contained 25 and 50% of either PSM or PPCPS protein replaced the fishmeal protein. A total of 400 silver catfish, with initial mean weight of 24 ± 0.46 g, were distributed into 20 tanks. For data four orthogonal contrasts were applied: control diet versus PSM diets; control diets versus PPCPS diets; control versus other diets; PSM diets versus PPCPS diets. The results indicated that the fish fed PSM diets had lower weight gain when compared to either control diet or PPCPS. The PPCPS do not affect growth and protein efficiency ratio. Lower albumin contents were found for the control diet fish for the contrasts control diet versus PPCPS diet and control diet versus other diets. The hepatic ALAT enzyme activity was higher in the fish fed the control diet (P < 0.05). The hepatic ALP was most active in fish that received the PPCPS diets, when comparing control diet versus PPCPS diets and control diet versus other diets. The hepatosomatic index was higher for fish fed the PPCPS. Our results indicated that PPCPS presents relevant nutritional quality for fish and can replace the fish meal protein up to 50% without affecting growth, PER and intermediate metabolites in silver catfish.