Optimizing Exogenous Protease Supplementation in Nile Tilapia Diets: Impacts on Performance, Fillet Quality and Intestinal Morphology

ABSTRACT This study aimed to determine the optimal inclusion level of a protease in the diets of Nile tilapia ( Oreochromis niloticus ) to enhance growth performance, nutrient utilization and fillet quality. Two experiments were made, one to determine the optimal level and a second experiment to validate these levels of supplementation in diets of tilapias. The first experiment consisted of six treatments, each with six replicates, and 25 fish per experimental unit. The treatments were as follows: crescent levels from 0, 25, 50, 75, 100 and 125 g/t of protease. In the second experiment, the treatments were as follows: (1) Positive Control (PC), meeting all nutritional requirements; (2) Negative Control 50 (CN50), with a 50% reduction based on the Precizyon PRO 50 matrix; (3) Negative Control 100 (CN100), with a 100% reduction; (4) Negative Control 150 (CN150), with a 150% reduction; (5) CN150 supplemented with 50 g/t of Precizyon PRO 50 and (6) CN150 supplemented with 75 g/t of Precizyon PRO 50. After analysing the results, it was observed that the addition of Precizyon PRO 50 to Nile tilapia diets significantly enhanced nutrient digestibility, growth, intestinal structure and fillet quality. Optimal levels of Precizyon PRO 50 were found to be between 71 and 77 g/t. Supplementing diets with 50–75 g/t of Precizyon PRO 50 effectively mitigated performance deficits caused by reduced amino acid levels, thereby improving growth, fillet yields and overall health.