Managing Phosphorus with Distillers Grains Diets

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 N g/day P Body Weight 800 lb steer 3.5 lb/d

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

Composition of Co-products 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 MetabolismDigestion 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

Land Area Required for Manure DisposalCorn - 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 ProductionManure Disposal - P

Managing Phosphorus with Distillers Grains Diets