Hidden Feed Risks: Heat Damaged Protein and Mycotoxins in Wet Years

We all know the importance of testing forage for nitrates during a drought year. But there are two other key concerns producers should watch for in a wet year. During wet years, hay producers may have difficulty getting hay dried and baled at optimal moisture content. Forage analysis should include evaluating heat-damaged protein (HDP), while corn grain should be checked for mycotoxins. Monitoring both helps guide ration and supplementation decisions that support healthy, productive livestock.

Heat Damaged Protein

Heat damaged protein is the protein associated with lignin. This protein often becomes associated with the fibrous portion of the forage through heat damage. Often, this can be caused by baling hay above 18% moisture. Haylages are also more susceptible to heat damage. Haylages are stored at a higher moisture content and heating can occur during ensiling.

Maillard Reactions

The heating reaction which causes the protein to bind to the fiber in the forage is known as the Maillard reaction. This reaction ties up protein with the lignin making that protein unavailable to the animal. Heat damaged forages are often associated with the caramelization of sugars in the forage. This results in a sweet, tobacco-like smell and makes it more palatable for livestock consumption. However, not all heat damaged forages have such an obvious change in color and smell.

Why it matters

Therefore, it is key to evaluate forages for HDP and use available protein in place of crude protein when significant heat damage has occurred. The bigger the gap between crude protein and available protein, the more likely the animal will not meet nutritional requirements if crude protein is used to determine a supplementation plan or balance a ration. The animal will be short changed, and health and production performance will be negatively impacted. Sick, underperforming livestock are a strain on any operation’s finances.

Mycotoxins

Often, we use corn grain as an energy supplement in a livestock diet. Under wet growing conditions, the risk for mycotoxin production in corn grain increases. Mycotoxins are invisible compounds produced by mold species that have detrimental effects on animal health. Mycotoxins negatively impact animal production through slowed growth, disrupted metabolism, and deleterious effects on reproduction.

There are several mycotoxins that are produced in the field during an exceptionally wet growing season. Aflatoxin, vomitoxin (DON), Fumonisin, and zearalenone are all produced in fields and can occur together. Co-occurrence of mycotoxins can exacerbate the negative effects of mycotoxins on animal health and production performance. Testing corn grain for a full mycotoxin panel, especially when grain appears discolored or damaged can prevent hidden losses.

In Conclusion

Forage and corn grain analysis is just as important after a wet growing season as during a drought. Testing for both heat-damaged protein and mycotoxins ensures that ration formulations reflect the nutrients truly available to livestock and help prevent costly setbacks in performance and reproduction. When in doubt, submit a forage or grain sample to the lab before feeding; the insight gained often saves far more than the test costs.