Effect of fishmeal replacement with a vegetable protein mixture on the amino acid and fatty acid profiles of diets, biofloc and shrimp cultured in BFT system

The objective was to evaluate the effect of fishmeal replacement on amino acid and fatty acid profiles of diets, biofloc and shrimp cultured in low water salinity (5‰). A commercial feed and four experimental diets elaborated using different combinations of meals (fish, corn, sorghum, wheat and soybean) were assessed. The feeds were labeled as C, 0, 10, 20 and 30; where C corresponded to the commercial feed while the other four were experimental feeds with a fishmeal content of 0, 100, 200 and 300 g kg^{− 1}. At the end of the culture, fatty acids (FA) and amino acids (AA) profiles were determined in biofloc, shrimp and pelleted feeds. To relate the AA quality of biofloc and feed, the essential amino acid ratio (A/E), and essential amino acid index (EAAI) were estimated. The water quality parameters, as well as the productive response of L. vannamei were statistically similar among treatments. The n − 3/n − 6 ratio varied widely among treatments (0.53–1.23 in feed and 0.46–0.93 in biofloc) without a tendency related to the fishmeal content. Nevertheless n − 3/n − 6 ratio of shrimp showed similar values (1.23–1.58). The EAAI in feed was above 0.90 in all treatments, except for 0; but in biofloc exhibited values above 0.87 in all cases. Except to 0 feed, the evidence indicates that in BFT, the fatty acid and amino acid composition of biofloc and shrimp are independent of the fishmeal included in the feed. The results suggest that biofloc could provide high quality protein and essential fatty acids in situ to compensate the partial fishmeal substitution.