Effects of phytase and multicarbohydrase on growth performance, bone mineralization, and nutrient digestibility in broilers fed a nutritionally reduced diet
J. Wang, Robert Patterson, Woo Kyun Kim
Abstract
An experiment was conducted to evaluate the effects of phytase and multicarbohydrase (MC) on growth performance, bone ash, and nutrient digestibility in broilers fed a nutritionally reduced diet. A total of 480 Cobb 500 male broilers were randomly allocated to 8 treatments with 6 replicates of 10 birds each. Experimental diets consisted of a positive control (PC); a negative control (NC) with the reduction of ME, CP, Ca, and nonphytate phosphorus by 75 kcal/kg, 1.5, 0.15, and 0.15%, respectively; NC plus phytase at 500, 1,000, or 1,500 FTU/kg as T3–T5; and further plus MC at 500 mg/kg as T6–T8. Results showed that during 0–18 d of age, feed conversion ratio (FCR) was increased (P < 0.05) in the NC group compared with the PC group; this was recovered (P < 0.05) in T5 group; BW gain (BWG) was increased (P < 0.05) in T6–T8, and FCR was decreased (P < 0.05) in T6 and T8, compared with the NC group. For bone mineralization, fat-free dry weight, weight, percentage, and concentration of tibia ash were decreased (P < 0.05) in the NC group compared with the PC group; T3–T5 increased (P < 0.05) tibia ash percentage and concentration, compared with the NC group, but only the tibia ash percentage reached to the level that of the PC group; T6–T8 increased (P < 0.05) tibia ash weight, percentage, and concentration compared with the NC group. Similarly, nitrogen retention and AMEn were decreased (P < 0.05) in the NC group and recovered in T3–T8; ileal P digestibility also was increased in T3–T8, to a greater level than that in the PC group. The results from contrasts suggested increasing phytase level with or without carbohydrase linearly increased broiler BWG, FCR, bone mineralization, N retention, and ileal P digestibility. Moreover, when combined with carbohydrase, increased phytase level in the diet linearly increased broiler energy utilization, while phytase alone showed no effect on AMEn. In conclusion, supplementation of a combination of phytase and MC could compensate the decreases in growth performance, bone ash, and nutrient digestibility caused by a nutritionally reduced diet.