Replacement of dietary fish meal by fermented soybean meal improves growth, energy metabolism, and innate immune response in Penaeus vannamei Boone, 1931 (Decapoda: Dendrobranchiata: Penaeidae)

Fishmeal (FM) is considered a preferred source of protein for aquatic feed due to its good palatability and digestibility, a balanced amino acid profile, and a low level of anti-nutritional factors (ANFs). Shortage of FM supply and increases in price, however, are major challenges faced by feed producers and aquaculture farmers. Fermented soybean meal (FSBM) has been proposed to partially replace FM because of its high nutritional value and low cost. The optimal FSBM concentration for substituting FM and effects of FSBM substitution on growth performance, energy metabolism, and immune response nevertheless remain unclear. We evaluated the effects of shrimp diets containing FSBM at 0% (FM), 25% (FSBM25), 50% (FSBM50), 75% (FSBM75), and 100% (FSBM100) on the shrimp Penaeus vannamei. FSBM50 led to a significantly higher weight gain (postlarvae 1927.36 & PLUSMN; 46.64%, young juveniles 237.00 & PLUSMN; 8.25%, and juveniles 153.96 & PLUSMN; 2.18%) than the other experimental and control diets in different stages of the shrimp. The FM group consumed less oxygen than the experimental diet groups. FSBM75 and FSBM100 led to a significantly higher ammonia-N excretion than FM, FSBM25, and FBSM50. All experimental diet groups exhibited a significantly higher O:N ratio (8.3 & PLUSMN; 0.8-9.4 & PLUSMN; 1.7) than the FM group (7.1 & PLUSMN; 0.2). Shrimp fed with FSBM25- and FSBM50-containing diets exhibited an increased total hemocyte count, and FSBM25, FBSM50, and FSBM100 led to a significantly higher superoxide anion production than FSBM75 and FM. FSBM substitution in shrimp diets resulted in a significantly higher phagocytic activity than the FM diet, suggesting that FSBM substitution improves the cell-mediated immune response in shrimps. In challenge trials with white spot syndrome virus (WSSV), all experimental diets led to a higher survival rate than the FM diet, and in Vibrio parahaemolyticus challenge trials, FSBM50 led to a higher survival rate than the other experimental and control diets, indicating that FSBM substitution in shrimp diets could improve the defense capacity of shrimps against WSSV and V. parahaemolyticus.