Safety of corn-expressed carbohydrase when fed to broilers at a high dietary level

SUMMARY Exogenous carbohydrase has been shown to reduce digesta viscosity and improve nutrient digestibility and broiler performance, particularly when feeding high fiber and, or, reduced energy diets. Objectives of the current study were to demonstrate the safety of a corn-expressed recombinant carbohydrase (AC1) in broilers when feeding at 10 times the maximum recommended dose. Parameters measured to demonstrate safety are hematology, serum biochemistry, gross necropsy, and any secondary negative animal performance response after feeding AC1 through 42 d of age. A total of 360 Cobb 500 male, day-old chicks were assigned to 1 of 2 dietary treatments with each treatment consisting of 12 replicate floor pens of 15 birds each. The birds were fed a nutritionally adequate corn and soybean meal diet either with or without AC1 addition, supplying 5000 U β-glucanase per kg of feed. No significant differences between treatments (P > 0.05) were observed for blood hematology or serum biochemistry parameters. No birds in the AC1 treatment exhibited pathological or toxicological symptoms during necropsy at 42 d of age. No significant differences (P > 0.05) were observed in body weight gain or FCR through 14, 28, or 42 d of age. Feed intake was increased with AC1 addition through days 14 and 28 (P