We all bale hay a little too wet from time to time, says University of Nebraska Extension Forage Specialist Bruce Anderson. Given the volatility of weather conditions in most parts of the country, it’s hard not to.

But Anderson cautions that too-moist hay can lead to heat damage that may reduce the digestibility of its energy and protein. Such hay often turns brown and has a caramel odor. While highly palatable and readily eaten by cattle, it may have low nutritional value because of the heat damage. 

Anderson says excess moisture in hay encourages the growth of microbes that generate extra heat.  Hay that maxes out at temperatures in the range of 110 to 120 degrees probably will suffer little damage. But wetter hay can get as warm as 150 degrees. At this temperature, it almost always becomes discolored, and nutritional value can be very low. Temperatures that exceed 170 degrees can trigger chemical reactions that produce enough heat to quickly raise temperatures over 400 degrees and cause fires.

If you’re forced to make wet hay, Anderson advises storing it away from buildings and other hay, and thoroughly testing its nutritional quality before feeding it.