Effect of Wheat Middlings, Microbial Phytase, and Citric Acid on Phytate-Phosphorus, Calcium, and Protein Utilization of Broilers

Abstract

A corn-soybean meal diet (CSB) (or Diet 1) containing 23% crude protein (CP) was used as the positive control, and another corn-soybean meal diet containing 21% CP and 15% wheat middlings (WM) (or Diet 2) was used as the basal diet, which was treated with four different treatments. Digestibility experiment was employed to discuss the collective effect of citric acid, and intrinsic and microbial phytase. By comparing and analyzing effects of them in the low-nutrient broiler diets, the results showed five treatments had similar effects on Tibia ash (%) (mg) ( P>0.05). Under the supplementation of bacterial phytase or citric acid, the daily body weight gain (ADG), gain:feed (G:F) ratio, and calcium (Ca) utilization were similar to that of standard-nutrient CSB diet (Diet 1) ( P>0.05). And, fecal phosphorus (P) and CP utilization were lower than ( P<0.05) that of Diet 1. But P utilization was significantly higher than ( P<0.01) that of Diet 1. However, the ADG, G:F, and CP utilization produced by supplementation of intrinsic phytase were lower than those of Diet 1, but other aspects were similar to those produced by Diet 1 ( P>0.05). In Diet 5, citric acid, intrinsic and bacterial phytase were added to the diet, which produced a 1.4% decrease on fecal P, a 7.2% increase on Ca utilization, which was significantly higher than ( P<0.01) those of the other four Diets, a 3.9% increase on G:F, which was similar to that of Diet 1, and a 2.3% increase on CP utilization, which was higher than ( P<0.05) that of the other three diets. In summary, the results of this study indicated that citric acid, intrinsic and bacterial phytase might have some additive or synergistic effects, and low-nutrient CSB diets with 15% wheat middlings, 750 U kg −1 phytase, and 3% citric acid might substitute completely for standard CSB in broilers.