Effect of exogenous protease supplementation on nitrogen balance, growth performance, and carcass characteristics of broiler chickens

Two studies were conducted to determine the effect of exogenous protease supplementation on daily N balance and apparent total tract digestibility (%ATTD) of N (Study 1) and growth performance, excreta quality, and carcass characteristics of broilers (Study 2). In Study 1, a total of 72 day-old male (Cobb 500) broiler chicks were individually placed in metabolic cages and randomly allotted to 1 of 6 treatments using a completely randomized design. The first diet was a corn-soybean meal basal diet formulated to meet or exceed Cobb 500 nutrient requirements (positive control, PC). The second diet was formulated by lowering the CP and standardized ideal digestible (SID) AA by 10% (negative control, NC). The next 4 diets were the NC diet supplemented with 500 g/ton Protease 1 (Allzyme Vegpro, Alltech Biotechnology Pvt. Ltd., India), Protease 2 (125 g/ton PT125, Jefo, Canada), Protease 3 (200 g/ton Ronozyme Pro-act (CT), DSM Nutritional Product Ltd., Switzerland), and Protease 4 (500 g/ton Cibenza DP100, Novus International Pte. Ltd, USA). Results showed no improvements in ATTD of N, growth performance, and excreta moisture of broilers fed diets supplemented with exogenous protease compared with the negative control. In Study 2, 800 day-old (Cobb 500) broiler chicks were randomly allotted to 1 of 8 treatments using a randomized complete block design. The treatments were the same 6 treatments in Study 1 with the addition of Protease 5 (350 g/ton Veterzyme Pro 700, Alivira Animal Health Limited, India) and Protease 6 (200 g/ton Protizyme, Lumis Enzymes, India). Exogenous protease supplementation, regardless of the commercial source, did not improve growth performance, excreta quality, and carcass characteristics of birds fed the NC diet. Protease supplementation increased feed cost per kg gain by P1.45 to 4.22 and reduced margin over feed cost by P4.12 to 7.97. In conclusion, supplementation of exogenous protease did not improve apparent total tract digestibility of protein, growth performance, excreta quality, or carcass characteristics of broiler chickens. Supplementation of these enzymes is not recommended since it only entailed additional to production.