Evaluation of in vitro Protein Digestibility of Different Feed Ingredients for Tilapia

Protein is a crucial component of fish feed, especially during early developmental stages, as it directly influences growth, health, and immunity. However, due to the rising cost and limited availability of fish meal, a primary protein source, there is growing demand for sustainable alternatives in aquaculture. This study explores the potentials of plant-based proteins as substitutes by evaluating their in vitro protein digestibility for tilapia (Oreochromis mossambicus). Crude gut enzymes from O. mossambicus were used in the pH drop method to measure relative protein digestibility (RPD). Protein content across samples varied from 19% to 61%, with fish meal showing the highest content (61.7%) and wheat bran the lowest (18.6%). In vitro digestibility, expressed as RPD% with casein as a reference, ranged from 62.7% to 83.3%. Soybean meal (83.3%) and wheat bran (78.8%) demonstrated significantly (P≤0.05) higher RPD compared to the reference diet (62.7%), fish meal (6%), and meat and bone meal (63.5%). These findings suggest that plant-based ingredients offer superior protein digestibility, supporting their use as effective, sustainable alternatives in tilapia feed formulations. South Asian J. Agric., Vol. 10, No.1-2, 2024: 82-91