Broiler responses to supplementation of phytase and admixture of carbohydrases and protease in maize–soyabean meal diets with or without maize Distillers’ Dried Grain with Solubles

1. This experiment investigated growth performance and nutrient utilisation responses of broilers to partial replacement of maize and soyabean meal in broiler diets with 100 g kg(-1) maize Distillers' Dried Grain with Solubles (mDDGS) as well as responses to supplementation of an admixture of carbohydrases and protease (XAP) or phytase individually or in combination in the diets. 2. A total of 288 one-day-old broilers were allocated to 8 treatments in a randomised complete block design and a 2 x 2 x 2 factorial arrangement of treatments. The three factors were two levels each of mDDGS (0 or 100 g kg(-1)), phytase (0 or 1000 FTU kg(-1)), and XAP (0 or 500 mg kg(-1)). 3. Each treatment had 6 replicate cages with 6 birds per replicate cage. The control diets were formulated to meet all nutrient requirements of broilers according to National Research Council recommendations of 1994, but were marginally deficient in non-phytate P and ME. 4. Weight gain and gain:food were higher in broilers receiving diets containing mDDGS. The coefficient of apparent ileal N digestibility was lower in diets with mDDGS. Phytase increased the coefficient of apparent ileal DM digestibility in all diets. 5. Phytase improved the coefficient of the apparent total tract DM retention independently of mDDGS and tended to improve the coefficient of apparent P retention in the diets without mDDGS. The enzymes were additive in their effects in the diets with mDDGS. Overall, the results showed that adding 100 g kg(-1) mDDGS to a maize-soyabean meal diet had no negative effect on growth when energy and nutrient concentrations were similar to the maize-soyabean meal diet, and that phytase or an admixture of carbohydrases and protease individually or in combination modestly improved nutrient utilisation independently of mDDGS addition. Combination of the enzymes did not produce greater benefit than the use of phytase alone.