COMPARATIVE EVALUATION OF THREE COMMERCIAL PROTEASE ENZYMES ON PERFORMANCE CARCASS TRAITS, BLOOD PARAMETERS, ILEAL NUTRIENT DIGESTIBILITY, AND PRODUCTION EFFICIENCY, IN BROILER CHICKENS FED STANDARD AND NUTRIENT-REDUCED DIETS

This study evaluated the effects of three commercial protease enzymes (A, B, and C), derived from Bacillus licheniformis, on broiler chickens fed either standard (CO) or nutrient-reduced (NC) diets over a 42-day period. A total of 600 one-day-old Ross 308 male chicks were randomly allocated into 10 treatment groups (5 replicates of 12 birds each), receiving diets with or without enzyme supplementation. Enzymes were included based on manufacturer-recommended dosages and matrix values: Enzyme A (600,000 U/g at 500 g/ton), Enzyme B (60,000 U/g at 250 g/ton), and Enzyme C (80,000 U/g at 50 g/ton). Performance parameters assessed included body weight gain (BWG), feed intake (FI), feed conversion ratio (FCR), carcass traits, blood biochemical markers (uric acid, creatinine), ileal nutrient digestibility (crude protein [CP], ether extract [EE]), and European Production Efficiency Factor (EPEF). Enzyme A significantly improved BWG (P = 0.002) and FCR (P = 0.006) in both C and NC diets, with higher FI observed in the NC + EA group (P = 0.012). Enzyme C improved FCR (P = 0.001) and increased carcass weight (P = 0.008), front half (P = 0.006), and back half weights (P = 0.019) in the CO diet. Enzyme B improved front half (P = 0.048) and total carcass weights (P = 0.044) in the CO diet. Blood parameters remained unaffected by any enzyme (P > 0.05). CP digestibility was significantly increased by Enzymes A (P = 0.004) and B (P = 0.007), while EE digestibility was unaffected significantly across treatments (P > 0.05). EPEF was numerically highest in the CO + EA group (468), indicating enhanced overall efficiency. These findings highlight enzyme-specific responses, with Enzyme A delivering the most consistent performance benefits, particularly under nutrient-adequate conditions. The results underscore the importance of selecting appropriate enzyme types and dosages relative to diet composition to optimize broiler productivity.