Hay producers in many parts of the country are dealing with a lot of rain and moisture. When hay is baled between 17 percent and 22 percent moisture, preservatives are effective at reducing mold growth. Studies conducted by Cornell University and the University of Illinois showed treated hay did not affect clinical measures of the yearlings’ well-being. This indicates preservatives did not negatively affect the horses.
Researchers agree that feeding horses hay treated with preservatives is a safe and common practice, especially when poor weather conditions exist for making dry hay.”
Source: The Paulick Report, June 3, 2024. Link.