Performance and Health Status of Juvenile Largemouth Bass ( Micropterus nigricans ) Fed Inclusions of Enzyme‐Treated and Low‐Oligosaccharide Soy Proteins

ABSTRACT Plant‐based proteins, such as soybean meal (SBM), have shown promising results in cultured species but also present challenges due to their nutrient composition and inherent antinutritional factors. This study investigated how the replacement of solvent‐extracted SBM with low oligosaccharide soybean meal (LSBM) or enzyme‐treated soybean meal (ESBM) impacts growth, body composition and health of largemouth bass (LMB; Micropterus nigricans ) fingerlings. The basal diet containing 50% SBM was replaced with either LSBM or ESBM at 0%, 40%, 60%, 80% and 100%. Replicate tanks of 15 LMB (8.55 ± 0.18 g) were assigned to one of the nine formulated diets and fed over six weeks. At termination, the treatment diets influenced the growth performance. Specifically, final weight was improved for LSBM80% (27.16 ± 0.90 g) compared to the basal diet (22.05 ± 0.59 g). Final weight, weight gain and thermal growth coefficient displayed improvements for 60%–100% ESBM‐inclusion diets (26.83–28.31 g, 18.31‐19.64 g and 0.52–0.57, respectively) compared to the basal (22.05 ± 0.59 g, 13.61 ± 0.61 g and 0.39 ± 0.02, respectively). ESBM60% (1.14 ± 0.06) and ESBM100% (1.18 ± 0.06) showed enhancement for the feed conversion rate compared to the basal (1.53 ± 0.06). Blood Cl − levels were reduced in ESBM100% (69.00 ± 4.00 mmol L −1 ) compared to basal diet (86.00 ± 2.00 mmol L −1 ). Mg 2+ levels were elevated in LSBM40%, LSBM60% and ESBM100% (3.59–3.69 mmol L −1 ) compared to the basal (2.88 ± 0.10 mmol L −1 ). Histological analysis of the distal intestine revealed no negative impact on intestinal health. These findings suggest that using higher inclusion levels of LSBM and ESBM proteins displayed enhanced growth in LMB compared to only using conventional SBM.