Ammonium polyphosphate versus dicalcium phosphate as a phosphorus supplement for growing-finishing swine

A totaL of 160 crossbred pigs were fed a sorghum-soybean meal diet with ammonium polyphosphate (APP) or dicalcium phosphate (DiCa) as supplemental phosphorus (P) sources for growing-finishing swine. The diets contained P levels of .5 and .4% for the grower phase and .4 and .33% for the finisher phase. Ammonium polyphosphate was evaluated on the basis of pig performance and bone development and compared with DiCa as a standard. The first rib and third and fourth metacarpals were removed from eight barrows from each of the four treatments. Replacement of DiCa with APP as the P supplement did not affect (P greater than .05) average daily gain, average daily feed and feed:gain ratio of growing-finishing pigs. No effect on bone variables examined on the first rib and third and fourth metacarpals was obtained between pigs fed APP or DiCa. Pigs on the lower supplemental P levels had lower (P less than .05) dry fat-free weight and percentage ash for all three bones. The breaking force of the first rib was less (P less than .05) for the pigs fed the lower P supplements of APP and DiCa than for pigs fed the higher level of DiCa. A trend was observed for an apparent decreased P availability from APP than DiCa when fed at the lower level of supplementation, but this trend was not observed when APP was added to provide a P level to meet National Research Council requirements. Ammonium polyphosphate as a P supplement for growing-finishing swine was satisfactory for performance and bone mineralization as compared with DiCa.