Testing for heat damaged protein in hay/forage put up too wet

The upshot is that when hay is put up too wet it can undergo a process called called enzymatic browning that promotes a process called the Maillard reaction.  This occurs in the presence of protein and sugars when forage overheats.  The resulting “Maillard” products will make protein in forage unavailable to the animal and hay may be unsuitable for ruminant digestion.  The only means I know of determining the level of heat damage is by analyzing the forage for ADIN (Acid Detergent Insoluble Nitrogen).  This value can be compared to total protein and the level of damage determined.  I know of no one on campus who does this.  One of the regional forage labs would conduct this routinely.

• High temperatures in bales (>170°F) can result in reactions between proteins and sugars called the Maillard reaction
• Hay impacted by Maillard reactions will be sweet/tobacco smelling and brown/caramel colored
• While highly palatable, the reaction creating this hay ties up protein, making it unusable for animal digestion
• If significant signs of Maillard reactions are seen in your hay, add a Head Damaged Protein (HDP) test to your forage analysis to get accurate Crude Protein contents for feeding decisions
• Caramelized hay also has a high likelihood of containing larger than normal amounts of mold growth.  Feeding free choice is a good option to minimize risk when feeding moldy hay
• Please don’t forget other contaminants that can be concerns in wet or dry years such as mycotoxins, nitrates, etc.
• Diluting the bad forage with good forage or grain is a possibility
• Check with an extension agent or other authority before feeding

The following two University of Nebraska factsheets may be helpful.

Please don’t forget other contaminants that can be concerns in wet or dry years such as mycotoxins, nitrates, etc.