Evaluation of amaranth ( Amaranthus caudatus L.) and quinoa ( Chenopodium quinoa ) protein sources as partial substitutes for fish meal in Litopenaeus vannamei grow‐out diets

Two groups of isonitrogenous diets formulated by replacing 15%, 25%, 35% and 45% of fish meal protein by amaranth meal and quinoa meal were used to evaluate the performance of Litopenaeus vannamei . Growth showed significant reduction ( P  < 0.05) in the group of shrimp fed with amaranth diets, with diet A15 showing the best specific growth rate ( SGR  = 2.81% day −1 ), but after the control diet AQ 0 (3.07% day −1 ). Diet A15 had significantly ( P  < 0.05) the best digestibility of dry matter (79.7%) and protein (88.4%) without differences compared to control diet AQ 0 (75.1% and 85.2%). Replacement with quinoa meal at any level tested did not significantly affect ( P  > 0.05) the shrimp growth performance. Shrimp fed with quinoa diets showed better SGR (3.05% day −1 ) than those shrimp fed with amaranth (2.56% day −1 ). No differences in feed conversion ratio appeared in either of the protein sources, but quinoa diets presented a better average (3.13) than amaranth diets (4.01). The apparent digestibility of dry matter and protein for quinoa diets was similar for all diets, but they were statistically different ( P  < 0.05) from the control diet. We conclude that quinoa meal can replace fishmeal up to 45%, whereas it can be replaced with amaranth meal up to 15%, without adverse effects on growth and survival.