Alvaro Garcia, extension dairy specialist at South Dakota State University, says he has heard a number of reports from lab technicians and farmers this fall expressing concern about mycotoxins. The caution is justifiable, he says, because of the weather conditions surrounding this year's harvest season.

It was rainy right before the corn and corn silage harvests in the Upper Midwest and then warm after that.

Garcia calls these "ideal conditions" for mold growth and the potential for mycotoxins in feed.

When conditions are appropriate, molds will produce mycotoxins, which are chemical compounds that can have a negative impact on performance and health of dairy cows, Trevor Smith, mycotoxin expert and professor of animal science at the University of Guelph in Canada, told an audience at the recent World Dairy Expo.

Probably the best way to minimize the problem is to use some type of mycotoxin absorbent, Smith said.

But here's an especially pertinent reminder for dairy nutritionists: Mycotoxin binders or absorbents can be non-specific, which means they also have the potential to absorb vitamins and minerals.

Based on limited data in other species (poultry, sheep and swine), some of the binding agents, including hydrated sodium calcium aluminosilicate and silicate minerals, may render some minerals and vitamins unavailable for absorption and metabolism.

It all depends on the level of inclusion, Smith says. "Under practical conditions, (the absorption of useful nutrients) it is not going to be a major issue at low levels of inclusion," he said. "I don't think it's an issue unless you feed high levels of absorbent."

It is very important, therefore, to follow manufacturer's recommendations when using these products.

One additional note: Garcia points out that Lon Whitlow, a mycotoxin expert from North Carolina State University, will speak on "Mold and Mycotoxins in Your Dairy Feeds" during the I-29 Dairy Conference, Feb. 9-10 in Sioux Falls, S.D. Well-known animal-welfare expert Temple Grandin will speak at the conference, as well. For more information, click here.