With the abundance of rain Oklahoma has received over the last several weeks, farmers and ranchers around the state are likely dealing with moldy hay and spoiled feed.


Moldy or spoiled feed can present a health risk for a multitude of species, said Kris Hiney, Oklahoma State University Cooperative Extension equine specialist.


“Hay can be unfit for livestock due to excessive moisture while baling or exposure to the elements, such as excessive rain or flooding. Molds present in the feed may contain mycotoxins, which can cause significant health issues,” Hiney said. “While only some molds produce mycotoxins, these are visually unable to be differentiated, and the presence of mycotoxins is difficult to assess.”


Animals that consume contaminated feeds can experience liver and kidney damage, neurologic disorders and estrogenic effects. While mycotoxins may not always cause clinical diseases, they can interact with animal stressors to decrease efficiency and reproduction and increase disease incidence, which may not be directly attributable by the producer to the feedstuff.


Adverse weather conditions during or post baling can allow mold growth, as it grows and thrives in warm and wet conditions. Hay with 14 to 15 percent moisture is subject to mold. Humidity, along with prematurely baling or excessive rain and flooding events can promote mold growth.


Hiney said it is important for producers of all forage consuming species, including cattle, sheep, goats and horses, to carefully monitor animal performance when weather conditions have increased the likelihood of spoiled or moldy forage.


“While mycotoxins typically are associated with grains, forage also can contain disease-causing agents,” she said. “Ochratoxin is typically associated with only death in young calves, as it’s rapidly degraded in the rumen in more mature animals. However, this mycotoxin has been associated with cattle deaths and abortions believed to be due to disruption phenylalanine metabolism.”


A fumigatus is a mycotoxin found more frequently in hay. Animals that consume hay containing this mycotoxin will exhibit symptoms similar to those of protein deficiencies or malnutrition.