CropWatch, Jan. 8, 2010: Test Discolored Hay for Heat-Damaged Protein Before Feeding

CropWatch, Jan. 8, 2010: Test Discolored Hay for Heat-Damaged Protein Before Feeding

January 8, 2010

Testing And Feeding Tobacco-Brown Hay

Last summer’s weather caused much hay to be baled too wet and now that hay has heated and turned brown.

Hay baled too wet or silage chopped too dry can get excessively hot and cause certain chemical reactions to occur. These chemical reactions and the heat that produces them will darken your forage and make it smell sweet like caramel.

Livestock often find such hay or silage very palatable, but the chemical reaction that caused this heat-damaged forage also makes some of the protein become indigestible. Unfortunately, tests for crude protein cannot distinguish between regular crude protein and heat-damaged protein. As a result, your forage test can mislead you into thinking you have more usable protein in your forage than is actually there.

If your forage test is done using NIR, heat-damaged protein is one of the analyses reported. If the heat-damaged protein is high enough, the test also will report an adjusted crude protein that is lower than the regular crude protein. However, I’ve found that the NIR test for heat-damage may not be accurate enough if your ration contains a lot of this forage and your ration has little or no extra protein in it for your cattle.

If you suspect such a problem, ask your lab to perform a special test to identify heat-damaged protein. Then have them use this test to correctly adjust the amount of crude protein your forage will actually provide to your animals.

Bruce Anderson
Extension Forage Specialist


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