Managing Swine Dietary Phosphorus to Meet Manure Management Goals
2002 University of Nebraska-Lincoln Extension Swine Report. A demonstration was carried out for 15 months at a 1,200-head growing- finishing facility in Holt County, Neb. The purpose was to document the impact of diet formulation on phosphorus excretion and the associated land area needed to utilize the phosphorus in the accumulated manure. The demonstration facility had four 300-head rooms. Prior to the demonstration, pigs in all rooms were fed diets formulated to contain 0.55-0.57% total phosphorus for all phases of growth. For the demonstration, two rooms were fed diets formulated to the University of Nebraska recommended levels for available phosphorus. The other two rooms were fed diets formulated to have the same amounts of all nutrients except phosphorus as the University of Nebraska diets using reduced amounts of dicalcium phosphate and phytase. Analysis of feces samples taken twice per month for the first 11 months, and monthly thereafter, indicated a 34% reduction in phosphate in the excreted feces of growing-finishing pigs fed diets containing phytase. Based on the phosphorus needs for 180 bu/acre corn, the switch from the previous diets containing 0.55 to 0.57% total phosphorus to diets formulated with decreasing amounts of phosphorus according to the University of Nebraska recommendations resulted in 49 fewer acres needed per year for land application of the manure. Formulating the diets according to the University of Nebraska recommendations and utilizing phytase and reduced amounts of dicalcium phosphate resulted in an additional reduction of 65 acres per year. In this demonstration, phytase was effective in reducing phosphorus excretion by growing-finishing pigs, even in diets formulated according to the University of Nebraska recommendations. Phytase use, combined with the reduction in estimated phosphorus excretion when switching from the previous nutrition program of 0.55 to 0.57% total phosphorus to decreasing amounts of phosphorus according to the University of Nebraska recommendations, resulted in an estimated 114 fewer acres needed per year for application of the accumulated manure at agronomic rates.