Effects of fermented and unfermented soybean meals on growth, body composition, and digestive enzymes in juvenile white snook (Centropomus viridis)

Abstract

A feeding trial was carried out to evaluate the effects of the partial replacement of fishmeal (FM) with soybean meal (SBM) or Lactobacillus acidophilus-fermented soybean meal (FSBM) on growth, feed efficiency, body composition, and digestive enzyme activity in juvenile white snook, Centropomus viridis. Five experimental diets were formulated, replacing 0 % (control diet), 25 %, or 40 % FM protein with SBM or FSBM. The control diet contained 328.15 g/kg FM and 243.59 g/kg SBM as primary and secondary protein sources, respectively. Each diet was administered for 80 days to quadruplicate groups of fish (n = 60 fish per diet) with an initial weight of 11.42 ± 0.83 g. SBM fermentation increased protein content and reduced trypsin-inhibitor activity. The addition of 370.14 g/kg SBM to aquafeed promoted growth in juvenile C. viridis, although with a significant intraperitoneal fat deposition. In contrast, the combination of 115.04 g/kg FSBM and 243.59 g/kg conventional SBM improved growth performance, the condition index, and protein retention, suggesting enhanced nutrient utilization. Juvenile C. viridis adapted to the antinutritional factors of SBM by increasing the activity of digestive enzymes, mainly acid and alkaline proteases. In contrast, FSBM had a lower impact on digestive enzyme activity than conventional SBM, indicating efficient nutrient utilization without increasing digestive capacity. The study underscores the potential of L. acidophilus-fermented SBM as a viable alternative to fishmeal in aquafeed, with promising benefits for growth and protein retention in white snook.