Effects of corn and soybean meal particle size on phosphorus use in turkey poults

Two 28-d experiments were conducted to evaluate the effect of grinding corn or soybean meal (SBM) to various particle sizes on P utilization in turkey poults. Dietary Ca was formulated to be 1.20% in the corn-SBM-based diets of both studies and nonphytate P (NPP) was calculated to be 0.40% in experiment 1 and 0.48%. in experiment 2. In experiment 1,corn that had been processed through a roller mill was used or was ground through 3 different screen sizes in a hammer mill to yield 4 corn particle sizes ranging from about 600 to 1,100 mu m. Initial (7 d) growth was reduced when the coarsest corn was fed due to lower feed intake. Phosphorus utilization was improved the first 2 wk as corn particle size increased as measured by incidence of rickets, tibia ash, and total P retention. Gizzard weight and phytate P retention were increased at 28 d as corn particle size increased. In experiment 2, corn was ground to approximately 850 mu m and commercial SBM (856 mu m) was used or ground to 2 finer particle sizes in a hammer mill. Gizzard weight and phytate P retention were increased at 2K d as SBM particle size increased. Other parameters were not affected at least partially due to the higher dietary NPP level fed to prevent severe rickets observed in the first trial. These studies show that young poults can utilize P better from coarser corn and soybean meal, especially when dietary P is low.