| Five experiments were conducted with chicks and pigs to determine the influence of particle size (.05 to 2.00 mm mean diameter) of defluorinated phosphate (DFP) on the bioavailability of Ca and P.;In the chick studies, a corn-soybean meal basal diet (.50% Ca,.46% P) was supplemented with two levels of Ca (.14 and.24%) and P (.07 and.14%) from calcium carbonate and monosodium phosphate (MSP) or from the five particle sizes of DFP, each providing.24% Ca and.14% P. Chicks (40.1 g) were on test for 17 days. Tibia breaking strength and ash were used to calculate the availability of Ca and P for each particle size, using slope-ratio procedures. The relative bioavailability of Ca and P in the DFP was 98, 106, 89, 99 and 101% for the smallest to the largest particle sizes, respectively.;In the pig studies, the treatments were a corn-soybean meal basal diet (.34% P), the basal with.06 or.12% added P from MSP and the basal with.12% added P from the five particle sizes of DFP. Pigs, averaging 14.5 kg initially, were on test for 35 to 41 days. Breaking strength and ash content of the third and fourth metatarsals and metacarpals were used to estimate availability of P, using slope-ratio procedures. The bioavailability of P in the five particle sizes of DFP was 97, 91, 99, 89 and 88% for the smallest to largest, respectively.;Six 35-day experiments (215 pigs; 14.6 kg) also were conducted to determine the availability of P in plant and animal protein supplements, cereal grains and cereal grain by-products. P was added (.10 and.20%) to a dextrose-soybean meal diet (.20% P) by the test ingredient or MSP.;The availability of P was 28, 21, 3 and 2% for soybean meal, canola meal, sunflower meal and cottonseed meal, respectively. The availability of P in animal protein sources was higher, averaging 92, 76 and 72% for blood meal, dried whey and meat and bone meal, respectively. Wheat, triticale, grain sorghum and corn averaged 53, 46, 12 and 10% in the availability of P compared with 71, 59 and 14%, respectively, for distillers grains, corn gluten feed and hominy feed. |
