Wet distillers grains with solubles (WDGS) can vary substantially in their nutrient composition. However, average concentrations of phosphorus in WDGS is 0.83% of dry matter, while corn grain has an average phosphorus concentration of 0.31%. Therefore, it depends on how much corn is displaced by the WDGS in the ration. For example, if a ration is formulated to contain 10% WDGS in place of corn, then there would be 1.04 lb more phosphorus per ton of feed.
University of Nebraska researchers have demonstrated that typical corn-based finishing rations with no WDGS meet the phosphorus requirements of the animals. So the additional phosphorus from WDGS will likely be excreted in the manure.
This is important to note when developing a nutrient management plan as the increase in phosphorus could mean that the manure will need to be spread over a larger number of acres. For more information, see the Iowa State University publication Use of Distillers Grains in Feedlot Diets: Impact on Phosphorus Excretion.
Author: Shawn Archibeque, Colorado State University
