Effects of Dietary Crude Protein and Protease Levels on Performance, Immunity Capacity, and AA Digestibility of Broilers

Exogenous proteases are promising to stimulate the application of low-protein diets for broilers. A total 540 1-day-old Arbor Acres male broilers were randomly assigned 9 groups with 6 replicates 10 birds. 3 × factorial, completely randomized arrangement was used evaluate effects dietary crude protein (CP) and protease levels on growth slaughter performance, immunity capacity, apparent ileal digestibility (AID) amino acids (AA). Dietary CP 20.0%, 19.5%, or 19.0% during starter phase, 18.0%, 17.5%, 17.0% finisher phase. Protease 0, 250, 500 mg/kg in throughout trial. The trial lasted 42 days. Weight gain feed efficiency decreased as lowered, but improved supplementation. had few interactions carcass characteristics, immune organ indexes, immunoglobulin concentrations. AID most AA by decrease In conclusion, reducing performance capacity increased AA. Almost independent level, addition broilers, probably through enhancement digestibility, no effect traits.