Reducing phosphorus excretion and loss potential by using a soluble supplement source for swine and poultry

Animal diets are often over-supplemented with low bioavailability phosphorus (P) sources in China, resulting in unnecessary excretion and loss of P to the environment. The effect of reducing dietary P supplementation and using a highly available P supplement for swine and poultry was determined. Manure collected in feeding trials involving the use of dicalcium phosphate (DCP) or mono-dicalcium phosphates (MDCP) that were < 1 or 17% water soluble, respectively, to increase dietary total P to amounts ranging from approximately 0.39 to 0.68% was analyzed for total P as well as different forms of P (H2O-, NaHCO3-, NaOH-, HCl- and residue-P). Manure total P varied with the amount of P supplemented, ranging from 14.5-22.3 g kg-1 for pigs, 4.7-13.6 g kg-1 for broilers and ducks, and 8.0-23.5 g kg-1 for layers. Determined using manure from pigs and birds receiving the highest supplemental amounts, MDCP reduced manure total P by up to 12.1% and H2O-P by up to 18.4% compared to DCP. Manure P extracted by weak NaOH and HCl was up to 9.4% higher for MDCP than DCP. Thus, using MDCP resulted in manure P that was lower in labile fractions than DCP. Soil leaching studies showed that dissolved P collected in leachate from manure was 9.4 to 32.6% lower when MDCP replaced DCP in the diet of pigs, broilers, ducks, and layers, confirming that MDCP reduced labile P in manure. Minimizing dietary P supplementation and using highly available MDCP as the supplemental source for pigs, broilers, ducks, and layers reduced P excretion and loss potential to the environment.