Managing Phosphorus with Distillers Grains Diets Allen Trenkle Iowa State University

Managing Phosphorus in Cattle Diets Establish requirements Use nutrient requirement tables – NRC Formulate diets to supply requirement - Preferably analyze feeds - Tables of nutrient composition of feedstuffs Can estimate excretion using available spreadsheets Input for manure management planning Corn contains more than adequate phosphorus for cattle

Nutrient Requirements of Growing Cattle Body Weight g/day N P 800 lb steer 3.5 lb/d

Phosphorus Requirement of Growing and Finishing Cattle – University of Nebraska Dietary phosphorus, % dry matter (Yearlings – Calves) Corn Gain, lbs/d Feed/gain

Composition of Co-products DGCDSCorn Protein N Oil10204 NDF Starch Ca P K S DGS = about 65% DG + 35% CDS Nutrients in corn concentrated about 3 times in DGS Replacing corn grain with distillers grains increases phosphorus intake

Phosphorus Metabolism Digestion Trial - ISU Cattle Experiment

Phosphorus Excretion Steers fed control, distillers soluble or wet DG Feeding distillers co-products: Did not change P metabolism Increased P excretion Feeding DGS is a manure management issue

Use of DGS in Feedlot Diets Diet Composition DGS % DM Protein % Phosphorus %

Land Area Required for Manure Disposal Corn - Nitrogen Balance Assumptions: Manure added based on crop removal – corn yield 150 bu/acre 50% of manure N lost as ammonia 1000-head feedlot occupied 304 days/year

Land Area Required Corn Production Manure Disposal - P