In extension, we say this a lot, but this year more than ever: Spending the money in the short run to know the nutrient value of the feedstuff, especially forages, will save money in the long run. Balancing diets for protein and energy without overfeeding either nutrient is important for optimizing the cow’s performance and your profitability, especially if your forage inventory is limited this winter.

##### Extension and Outreach Beef Specialist / Iowa State University

Supplementing grain and grain co-products is a viable option to supply additional energy and protein to beef cow diets while stretching hay supplies. However, it can be challenging to determine which feed resource is more economical.

In order to accurately compare, feedstuffs need to be on the same playing field, so some simple math is necessary to look at each nutrient on a dry matter (DM) basis per unit of nutrient of interest.

For many low-quality forages, such as mature hay or cornstalks, protein is often needed. Here is an example comparing corn and dried distillers grain (DDG) as a protein source, by knowing the price (as-fed, delivered to the farm), dry matter (DM) and crude protein (CP) of each ingredient.

Corn
\$3.65/bu, 85% DM, 8.6% CP

Price per unit of CP
\$3.65/bu ÷ 56 lb/bu ÷ 0.086 (%CP) ÷ 0.85 (% DM) = \$0.89/lb of CP

DDG
\$150/ton, 90% DM, 30% CP

Price per unit of CP
\$150/ton ÷ 2000 lb/ton ÷ 0.30 (%CP) ÷ 0.90 (% DM) = \$0.28/lb of CP

At these prices, DDG is a more viable option than corn if additional protein needs to be supplemented. The same steps can be followed to determine price per unit of energy, replacing the CP percentage with the total digestible nutrients (TDN) percentage of the feedstuffs.

Several universities have put together decision aids to compare feedstuff value and purchase decisions. The Iowa Beef Center at Iowa State has a Feed Energy Index excel-based tool to evaluate the value per unit of energy, which can be found on our website (Iowa State University Beef Center - calculator).

If you need assistance budgeting winter feeds or developing least-cost rations to fit the needs of your operation, contact your nutritionist or local extension beef specialist.

• ### Erika Lundy

• Extension Beef Program Specialist
• Iowa Beef Center - Iowa State University
• Email Erika Lundy