A wet, humid fall can not only can delay harvest but can also set the stage for mold growth and increased risk of mycotoxins. The 2019 harvest was a wet one in many regions of the U.S., and even if the season ended on a dry note in one area, feedstuffs might have been exposed to molds in the field, during harvest or in storage, making the presence of mycotoxins a possibility, according to an announcement from Phibro Animal Health Corp.

In dairy cattle, mycotoxins can cause reduced milk production, digestive disorders, intestinal irritation, diarrhea, poor feed intake and, in some cases, suppressed immunity. The mycotoxins most likely to affect dairy cattle are aflatoxins, deoxynivalenol (DON, or vomitoxin), fumonisins, zearalenone and T-2 toxin, Phibro said.

“DON is often used as a screen for mycotoxin-contaminated feedstuffs, since its presence indicates that the crop’s growing, harvesting and/or storage conditions were conducive to mold growth and subsequent mycotoxin formation,” said Dr. Dennis Nuzback, Phibro Animal Health research technical manager. “However, the majority of feedstuffs usually contain multiple mycotoxins simultaneously, so it’s important to know which ones are present in order to manage the problem.”

The presence of mold may cause dry matter losses, lower nutritional values and potentially formation of mycotoxins, Phibro said. Late-harvested grain, along with grain that was dried or stored improperly, may also contain mold and mycotoxins.

Nuzback advised producers to be vigilant and to take the following steps to reduce the incidence of mycotoxicosis in their dairy herds:

“Buffers, effective fiber and direct-fed microbials can help restore rumen function in dairy cows,” Nuzback said. “Since many nutrients interact with mycotoxins and modify toxicity, optimal levels of nutrients -- including protein, energy and antioxidants -- can prove helpful in reducing the adverse effects of mycotoxins. Adsorbents and immunomodulators are the first line of defense against mycotoxins in feed.”