EFFECT OF FIBER AND PHYTATE SOURCE AND OF CALCIUM AND PHOSPHORUS LEVEL ON PHYTATE HYDROLYSIS IN THE CHICK

Broiler chicks were fed a corn-soybean meal diet or a corn-soybean meal diet containing either 15% rice bran, 15% wheat bran, 15% alfalfa meal, 10% cellulose, or 10% cottonseed hulls. All diets contained 3190 kcal/kg of metabolizable energy, 22.8% protein and either 1.0% Ca and 0.5% nonphytate P (Pnp) or 0.85% Ca and 0.42% Pnp. The diets were fed for 3 wk at which time a digestion trial was conducted to determine the amount of phytate hydrolyzed. Chicks consuming diets containing the lower levels of Ca and Pnp hydrolyzed more phytate than those fed the higher levels of Ca and Pnp except when the diet contained rice bran. Less phytate was hydrolyzed in the rice bran diet at the lower Ca and Pnp levels. Phytate hydrolysis was not affected by wheat bran but was reduced by cottonseed hulls. At the lower levels of Ca and Pnp, alfalfa meal and cellulose significantly increased phytate hydrolysis by chicks. The hydrolysis of phytate was influenced more by Ca and by source than by fiber or by level of phytate fed.