Influence of Steam Pelleting and Dietary Calcium Level on the Utilization of Phosphorus by the Pig

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Abstract
Four corn-soybean meal diets were prepared with two levels of added inorganic phosphate (none or .16%) and two levels of calcium (.65 and .95%). The diets were fed as meal or as pellets to three replicate pens containing two barrows and two gilts for 8 weeks from an initial weight of 25 kilograms. Radii and femurs were subjected to histological, chemical and mechanical evaluations. A balance study was conducted using four 25 kg barrows for each diet. The absorbability of the plant phosphorus in the lower calcium, low phosphorus diet was increased from 30 to 40% by steam pelleting. Supplementing the low calcium diet with phosphorus increased calcium and phosphorus retention. Steam pelleting the lower calcium, low phosphorus diet improved gain (590 to 720g/day), but this improvement was less than that obtained by adding .16% of inorganic phosphate phosphorus to the diet (903g/day). On the diet with the higher calcium and phosphorus contents the pigs gained 847g/day. Bone ash contents of the radius and femur were increased markedly by phosphorus supplementation as were their breaking strengths. Increasing the calcium level of the phosphorus supplemented diet had no influence on the radius, but tended to increase the strength of the femur. Copyright © 1975. American Society of Animal Science . Copyright 1975 by American Society of Animal Science.