Moldy Hay

This year’s weather made harvesting hay difficult to say the least. In many instances, hay was damaged by rain between cutting and harvesting. This has lead to an influx of calls with the question “is moldy hay safe to feed to cattle?” Moldy hay has been fed to cattle as long as we have had machinery to harvest hay. So does that mean that it is safe? The short answer is not really.

Moldy hay can contain mycotoxins that will results in poor animal performance and sometimes death. Tests can be ran for mycotoxins, however, a standard (affordable) test only tests for a few of mycotoxins that exist. Furthermore, mycotoxins may be patchy. There may only be 1 out of 10 bales contain a deadly mycotoxins making it very difficult to detect when sampling. Even if a mycotoxins test results are negative, the only assumption that can be made is that the sample submitted did not contain mycotoxins that could be found from the test. As a standard rule of thumb, it is not advisable to feed moldy hay. So what should be done with moldy hay?

The safest option would be to land apply the hay as a fertilizer where there are no cattle grazing. A ton of fescue hay contains approximately 35 pounds of nitrogen, 18pounds of phosphorus and 50 pounds of potassium.

Many farmers have gotten by in the past by limiting the amount of moldy hay fed to cattle. Like all things, the dose makes the poison. Hay that contains small amounts of mycotoxins can be diluted with other non-moldy grain and hay and animals will perform at or near optimal performance if the ration is balanced accordingly.