Droughty growing conditions increase the risk of aflatoxin on corn and other feeds, which in turn can be passed into the milk.
Aflatoxin is a known carcinogen for both humans and livestock, and the Food and Drug Administration prohibits the sale of milk with more than 0.5 parts per billion (ppb).
Already, some dairy farmers in Illinois have had milk rejected because it contained more than this level, says Mike Hutjens with the University of Illinois.
Hutjens and Jim Baltz, also with U of I, have put together a 9 ½ minute video on identifying and managing aflatoxin. Hutjens notes that lactating rations can contain no more than 20 ppb of aflatoxin, since dairy cows excrete one to two percent of the aflatoxin in their feed into milk.
Hutjens recommends testing feed for aflatoxin prior to feeding. If contaminated, the feed should be diluted with wholesome forages or grains. Flow agents, or myctoxin binders, can be added as well. Ammoniation of the feed will neutralize aflatoxin, but ammoniated feed cannot be sold for human food or transported across state lines.
For much more detail on managing aflatoxin, cick here to view the video.