Straw is a common, high-fiber, low-energy ingredient in U.S. dairy heifer rations. While we normally monitor grain quality to watch for harmful mycotoxins, it turns out straw can carry its own mycotoxin risk, according to a recent feed quality evaluation by Alltech, Inc.
Each year, Alltech conducts comprehensive mycotoxin testing programs in the U.S., Canada, and Europe to assess the mycotoxin risk in newly harvested grain crops. For the first time this year, wheat and barley straw were added to the sampling in Europe.
Danish farmers were worried about the damaging effects of wet weather both pre- and post-harvest. Because excessive moisture delayed straw harvest, the crops lay in the field for extended periods, damaging quality and fueling mold contamination.
A total of 70 straw samples from Denmark were evaluated. Deoxynivalenol (DON) was identified in 84% of samples, and emerging mycotoxins were found in 70% of samples. All told, 95% of samples contained some form of mycotoxin, with 50% containing two or more.
According a bulletin on mycotoxins in forage shared by the University of Wisconsin, DON may be a marker for other mycotoxins in contaminated feeds. When young dairy animals consume mycotoxins, they can be at risk for feed refusals, diarrhea, and immunosuppression. Additionally, mycotoxin-induced outcomes may be vague, and include unthriftiness, rough haircoat, poor body condition, and reproductive problems.
Alltech technical advisor and veterinarian, Dr. Radka Boutova, DVM, suggested adding straw to the list of feedstuffs that are screened for mycotoxins if it is a commonly used ingredient in a young stock ration. This is particularly important if the straw crop was stressed and/or delayed in the field due to unfavorable weather conditions, or for any straw that shows visible signs of mold.