Undesirable growing or storage conditions can lead to mold growth and development of mycotoxins, such as zearalenone in wet distillers grains, sugar beet pulp and other by-products.

“Producers should be concerned because excessive levels of zearalenone could affect reproduction,” says J.W. Schroeder, North Dakota State University extension dairy specialist. “Because mold can develop in many wet by-products if the conditions are right, I’m reminding dairy managers who use large amounts of by-products to use caution, especially for cows in the breeding pen.”

Schroeder urges producers to be mindful of climatic and storage conditions that could increase the presence of spoilage and mycotoxins. And, if you are seeing shortfalls in herd reproduction, look at the whole picture, including your feed supply.

“The U.S. does not have established tolerance limits for zearalenone in feed for livestock, but common sense when developing your feed ration goes a long way,” Schroeder adds. “If you are feeding a host of by-products or feeding above the recommended amounts for any given by-product, there always will be some risk when mycotoxins are present. Adding challenges to a cow’s diet is just one more potential impediment to her full-time job of producing milk and bearing a calf.”

Zearalenone in byproducts is not a new problem, and ruminants appear to be able to consume small amounts of feed with mycotoxins with no problems, research shows.

“However, while such feeding typically may present no risk to animal health, producers should be mindful of climatic and storage conditions that could increase the presence of these toxins,” Schroeder says. “I just want producers to be aware and use prudence when making changes to the dairy cow diet. And, if they are experiencing some shortfalls in herd reproduction, they should be sure to look at the whole picture, and when looking at the feed, watch for unwanted spoilage.”