Growth performance and nutrient utilization of broiler chickens fed diets supplemented with phytase alone or in combination with citric acid and multicarbohydrase.

An experiment was conducted to determine the effect of supplementing a corn-soybean meal-based diet with phytase alone or in combination with citric acid (CA) or multicarbohydrase, a preparation containing nonstarch polysaccharide-degrading enzymes, or both, on growth performance, nutrient utilization, and bone mineralization. A total of 360 one-day-old broiler chicks were assigned to 6 dietary treatments, consisting of 12 pens of 5 birds each, and were fed experimental diets from 1 to 21 d of age. The diets included a positive control (0.46% nonphytate P; 1.1% Ca) and a negative control (NC; 0.26% nonphytate P; 0.89% Ca) without or with phytase (600 U/kg) alone, phytase plus CA (5 g/kg), phytase plus multicarbohydrase (Superzyme OM; 0.6 g/kg), or phytase (Ronozyme P-CT) plus CA and multicarbohydrase. Birds fed the positive control diet had higher (P<0.05) BW gain (764 vs. 594 g/21 d) and tibia ash content (50.0 vs. 38.3%) than those fed the NC diet. Phytase improved (P<0.05) BW gain (632 g/21 d), which increased further (P<0.05) to 673 g/21 d for the phytase plus multicarbohydrase diet. In contrast to phytase alone, phytase plus multicarbohydrase supplementation improved (P<0.05) feed conversion ratio of the NC diet from 1.37 to 1.32. Tibia ash content for the NC diet increased (P<0.05) from 38.3 to 42.4% due to phytase addition. Phytase improved (P<0.05) ileal digestibility of P from 29.5 to 43%, and the addition of CA or multicarbohydrase, or both, to a phytase-supplemented diet further increased (P<0.05) P digestibility to 51.5, 53.4, and 54.3%, respectively. Phytase addition improved (P<0.05) diet AMEn content from 2,959 to 3,068 kcal/kg, which tended (P<0.06) to increase further with CA (3,150 kcal/kg) or multicarbohydrase (3,142 kcal/kg) addition. No beneficial interactions were detected between CA and multicarbohydrase for all response criteria measured. Results show that addition of multicarbohydrase to the phytase-supplemented broiler diets improved nutrient utilization and growth performance.