A preparation of keratinase (KE, 400,000 enzyme units/g) was evaluated as a feed additive for its
effects on growth performance, nutrient digestibility and intestinal development in broiler chickens.
Four experimental diets were arranged as a 2 × 2 factorial with two sources of protein, either soybean
meal (SBM) alone or a combination of SBM and cottonseed meal (1:1 on crude protein basis) and with
or without 1.0 g KE/kg diet. Dietary supplementation of KE increased body weight gain from 1 to 21
days of age and improved feed conversion ratio from 1 to 42 days of age. Also, KE supplementation
enhanced nitrogen retention (P