Nutritional assessment of linseed meal (Linum usitatissimum L.) protein concentrate in feed of silver catfish

Abstract Linseed protein concentrate (LPC) was produced in the laboratory and subsequently a feed assay was performed to evaluate the inclusion of increasing levels of LPC in replacement of fish meal on growth, nutrient utilization, metabolic responses and goblet cells of silver catfish (Rhamdia quelen). Five isotopic and isocaloric diets were formulated, including 0, 100, 200, 300 and 400 g/kg of LPC protein replacing the fish meal, respectively. Each diet was randomly distributed to quadruplicate groups of 25 fish (initial average weight of 6.13 g) per tank, totaling 20 tanks. The crude protein of LPC was lower (P 0.05) than animals submitted to the 0 g/kg LPC diet. Diets of 300 and 400 g/kg LPC provided higher (P