Effects of Different Proteases on Protein Digestion In Vitro and In Vivo and Growth Performance of Broilers Fed Corn–Soybean Meal Diets

This study was conducted to investigate the effects of different proteases alone or in combination on protein digestibility broilers. In vitro, properties four broilers, including acidic protease (AcP), alkaline (AlP), neutral (NeP) and keratinase (Ker), endogenous activity their common ingredients broiler diets were investigated using a gut-mimicking model. vivo, 640 1-day-old male broilers randomly divided into 8 groups 10 with replicates birds per replicate cage. Eight dietary treatments included corn–soybean meal basal diet (control), 1.6 U AcP/g, 0.8 NeP/g, AlP/g, 0.4 Ker/g, AcP/g + Ker/g added. The experiment lasted for 31 days. results showed that optimum pH values AcP, NeP, AlP Ker 3.0, 9.0, 11.0 respectively. recovery proportion 37.68% at 3.3–6.2. AcP increased vitro crude (IVCPD) decreased ileal apparent 31-day-old (p < 0.05). All supplementation reduced amino acids compared control Acidic had positive effect trypsin chymotrypsin activities, while negative effect. average daily gain feed intake significantly 0.05) supplemented group. When adding exogenous diets, sensitivity digestive activity, dosage should be taken account. addition, level considered.