Effects of steam pelleting and extrusion of feed on phytate phosphorus utilization in broiler chickens

Three experiments were conducted to determine the effects of pelleting and extrusion of feeds on the utilization of phytate P by broilers. The first experiment investigated the effects of pelleting the whole corn-soybean meal (SBM) diet, the corn, or SBM separately on phytate P utilization. The P-deficient basal diet contained 0.5% total P and 0.2% phytate P. Steam pelleting the whole diet, the corn, or SBM separately did not decrease the severity of the P deficiency obtained and there were no indications of increased phytate P utilization. In the second experiment, the whole corn-SBM P-deficient diet was extruded. Extrusion of the diet did not influence bone ash and P rickets, both sensitive criteria of P deficiency. Extrusion decreased Ca, P, and phytate P retention and decreased the ME value of the diet. In the third experiment, phytate P retention by chickens fed three commercial pelleted diets was compared to chicks fed the corn-SBM P-deficient diet. Phytate P retention by the chickens fed the commercial diets was much lower than retention by chickens fed the corn-SBM P-deficient diet. These studies gave no indication that pelleting or extrusion of corn-SBM diets would increase phytate P utilization by broiler chickens.