Beneficial Effects of Versazyme,a Keratinase Feed Additive,on Body Weight,Feed Conversion,and Breast Yield of Broiler Chickens

Versazyme (VZ) is a keratinase-based feed additive. Broiler diets were formulated with low (95%), medium (100%), or high (105%) CP and amino acid levels relative to US Poultry Industry Reporting Service averages (2003). In each diet, amino acid minimums were maintained relative to the percentage of CP. The protein levels were as follows: starter—21, 22, 23%; grower—19, 20, 21%; finisher—17, 18, 19%; and withdrawal—16, 17, 18%. Mixed sex broilers 0 to 48 d of age were fed the 3 protein levels with and without VZ (0.10%) in a 3 × 2 factorial experiment. Statistical main effects indicated 48-d BW was greater on the high protein diets (2.42 kg) compared with low protein (2.36 kg), with the medium protein diet being intermediate (2.40 kg). Overall, VZ significantly (P < 0.01) improved 48-d BW 2.54% (from 2.36 to 2.42 kg, P < 0.01), feed conversion ratio 1.62% (from 1.912 to 1.881, P < 0.01), and breast meat yield 1.68% (from 31.57 to 32.10%, P < 0.01). The improvements in BW and feed conversion ratio by VZ were greatest with the low protein diets. However, VZ produced the greatest improvement in breast meat yield at the medium and high protein levels. This enzyme feed additive apparently improves the utilization of amino acids by broilers fed diets formulated to commercial specifications.