Feeding Urea to Newly Weaned Calves - Frequently Asked Questions

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 Can I feed Urea to newly weaned calves?
Young calves, under 450 pounds or 120 days of age cannot use urea as a protein source efficiently. If urea is to be added to a ration, calves larger than 450 pounds and older than 120 days, need to become accustomed to the urea in the ration over a 10 to 14 day adjustment period.

What does urea provide in a ration?
Urea provides "non-protein nitrogen" in a ration. This protein is not from plant sources, but is suitable for use with some restrictions. There is no energy, macro- or micro- nutrients or vitamins in urea.

How much protein does urea contain compared to canola meal?
Canola meal contains 36 % protein, all of which is considered "natural" protein. Feed grade urea, contains 287 % protein equivalent, but all the protein is from a "non-protein nitrogen" source.

What is the maximum feeding level in a calf ration?
After the 14-day adaptation period, urea can contribute:

  • A maximum of 33% of the total "protein in the ration
  • Inclusion in a ration must not exceed 1% of total feed consumed on a daily basis
  • Not to exceed 2% of the grain portion of the ration
What is needed to help use the "non-protein nitrogen" in the ration?
Energy from a carbohydrate source such as grain is required. A minimum of 3 to 4 pounds of grain per head per day is needed to improve urea utilization.

When urea is broken down in the rumen, ammonia is produced. Ammonia can cross into the blood stream and be transported to all parts of the body. The liver converts the ammonia back to urea, and in turn is re-used by the animal when passed back into the rumen through saliva. If the ammonia levels in the blood get too concentrated, carbon dioxide is not released in the lungs and this interferes with oxygen absorption. If the condition gets severe, animals can die of oxygen deprivation.

Know Your Feed Terms

Prepared by Barry Yaremcio, Ag-Info Centre, Alberta Agriculture & Forestry
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For more information about the content of this document, contact Barry Yaremcio.
This document is maintained by Brenda McLellan.
This information published to the web on November 7, 2003.
Last Reviewed/Revised on September 21, 2017.