Feed Lot Magazine Online, Be Especially Wary of Aflatoxin this Year

Earlier this winter I visited a client feedyard in the Midwest and received the shock of my life. Laying out on the ground was 20 loads of corn. Admonishing the feedlot manager that we can't do that, his reply was that elevators were doing the same thing. The corn harvest was so large that storage simply was not available. Indeed there is grain stored outside throughout the Corn Belt.

For the record, I sampled the grain and it came up negative for a battery of mycotoxins. Aflatoxin and its malevolent poisonous cousins require warm, humid conditions to grow. As long as the grain is used up before warm weather, we might squeak by. But the bottom line is that storing grain or oilseeds outside is like playing Russian roulette. A little precipitation and a few warm days, and we're in trouble.

In cattle, the first sign of aflatoxin is reduced consumption. Liver failure will follow and then death. It is important to realize the 300 ppb legal limit for feeding (for beef cattle) does not consider the effect on the animal. At 300 ppb there will simply be no residues in the meat. This was the FDA's only concern in setting that limit. Under almost no circumstances would I knowingly feed a level that high.

Anything over 20 ppb will cause residues in milk. Therefore it is illegal to feed over 20 ppb to dairy cows. It would also be ill advised to feed over 20 ppb to beef cows nursing calves.

Testing can be deceiving in many ways. To begin with, sampling for aflatoxin is not like analyzing for normal nutrient profiles. Unlike protein, fat, fiber or minerals, distribution is not uniform. There can be "hot spots" in isolated areas. A leak in a storage area or a dead spot with respect to forced air drying can produce a "hot spot", as can mixing different sources of corn together.

There can be a myriad of mycotoxins other than aflatoxin; many of which are even more detrimental (to cattle). Because aflatoxin is such a threat to humans (aflatoxin is a powerful carcinogen known to be a factor in liver cancer), a disproportionate amount of attention is paid to aflatoxin. As a result, a lot of people think of aflatoxin as synonymous with mycotoxin problems. This is not necessarily true. A sample can be negative for aflatoxin, but be positive for some other very powerful mold-produced toxins.

Fusarium molds for example can be lethal to cattle. There are known to be over 100 species of Fusarium molds, yet at last count there were laboratory tests available for only 17.

Horses. Fumonisin is another mold that is common to corn, and a particularly bad one for horses. Fumonison is so toxic to horses that some horse feed manufacturers will not include corn in horse feed formulations. (In horses it causes what is known as liquidification of the brain.) With all the corn that is stored outside this year, the source becomes even more important.

A quick test on corn can be performed with a blacklight. Viewed in total darkness, most molds on corn will glow an iridescent purple color. This is not a replacement for a laboratory analysis, but a laboratory analysis is not the final word either. I have had cattle die on grain that tested negative for mycotoxins.

The ultimate sensitivity test is the animals. If cattle suddenly back off feed and no clear non-mycotoxin problem is obvious, change grain sources. Don't wait for the lab work to come in. It may or may not tell you anything. The cattle are telling you something right now.

Salvaging aflatoxin grain. There is a widespread myth that aflatoxin tainted grain can be salvaged by roasting. This is absolutely not true. Aflatoxin is an extremely heat stabile compound, and heat processing will in no way lessen the potency.

There are ways, however, to chemically treat tainted grain. There are commercially available compounds, but ammoniation is the most inexpensive treatment. Although not legal at the federal level, several states recognize ammoniation as a viable means of detoxifying aflatoxin. Much like treating straw, the grain must be sealed in plastic or put in an air tight silo. Ammonia is then injected and allowed to remain sealed within the structure.

The bottom line is that aflatoxin and other mycotoxins are an ever present danger for grain that goes out of condition. Given the lack of storage for the corn crop this last season, we must be particularly wary this year.

Several books and a subscription newsletter by Dr. Price are available. For more information, call FEED*LOT at 800-798-9515 or visit www.zianet.com/nutconsult.