The dilution solution
BROOKINGS, S.D. -- Keeping a watch for mycotoxin molds in grain storage has been common practice for years now, but recent information released by researchers at the dairy science department at South Dakota State University in Brookings point up ...
BROOKINGS, S.D. -- Keeping a watch for mycotoxin molds in grain storage has been common practice for years now, but recent information released by researchers at the dairy science department at South Dakota State University in Brookings point up a threefold increase in the amount of these toxins present in dried distiller's grains.
"When we see something in the corn crop, we really worry about distiller's grains and the co-products," says Arnold Hippen, SDSU researcher and professor of dairy science. "The starch is removed from the corn grain -- that's 60 percent to 70 percent of the corn grain -- so you pull that out and everything else is left: minerals, proteins and toxins. So you get a threefold increase in concentration."
The Food and Drug Administration has set a mycotoxin limit of 20 parts per billion in corn. Corn containing more than that cannot be sold in interstate commerce. It should not, in general, be fed to young poultry, swine, livestock or to lactating animals, and it must not be milled for human consumption.
The recent increase in the dependence upon DDGs in ruminant feed is bringing the toxin questions to the forefront.
"The reason this came to the front is because there have been a lot of questions from producers about it, and we felt there was a need to address it," Hippen says.
Aflatoxins can be passed from a dairy cow into its milk, and with state and federal restrictions on the allowable toxin concentrations in milk, the primary risk he sees to dairy operations would be loss of the milk market.
"If it's X-level in the feed, it will be X-level in the milk, so that's the biggest immediate concern. You can safely tolerate higher levels in feedstuffs than what the legal limit is in the milk," he says.
Common indicators of dangerous levels of toxins in feed will present themselves in the herd rather than a single animal. Symptoms include decreased feed intake, more disease issues and reproduction issues, but are not limited to these.
"It runs the gamut of all the nasty things there are," Hippen says. "So when you do see a reduction in performance, dry matter intake is probably your first (suspect). It might be a good idea to just be checking your feedstocks. Check your own first, then the DDGs."
Here, Hippen recommends first getting the test results form the ethanol plant when the DDG is purchased.
"A lot of the plants are running their own tests. (South Dakota-based) POET, for example, is really good at that, and in so doing, to maintain that marketability, I know POET has a quality control where they make sure that the levels are brought down in the marketed product," he says.
If problems do arise, he recommends having the feed tested at commercial and independent laboratories as opposed those at the ethanol plant.
"Keep your ears open, too. If all of your neighbors have tested corn and are high in aflatoxin, it would be a good idea just to get it checked," he says. "But if it's a good crop year and we're not seeing much reports and their labs say it's clean, then I wouldn't worry too much about it."
But if a supply of DDGs are found to be above safe levels, producers still can make use of it. DDGs typically are used as only a portion of ruminant diets, and reducing the ratio of DDG to the rest of the feed will allow safe use.
"Really, the practical way to deal with these problems, whether it's corn you've harvested from the field or corn silage, I kind of hate to put it too lightly, but dilution is the solution," Hippen says. "If I feed less of it and more of something that's clean, that will keep levels down."
Level limit guidelines
- The level of aflatoxin an animal can tolerate will depend upon the age and sex of the animal, its health status and overall management level of the farm.
- To avoid contamination of milk, lactating dairy cattle should not receive more than 20 parts per billion in the total ration. Calves should not receive milk from cows fed in excess of 20 p.p.b., because they can ingest aflatoxin from the milk.
- Beef cattle can tolerate higher levels of aflatoxin, but yearlings and mature cows should not receive more than 400 p.p.b. in the total ration. Weanlings should not receive more than 100 p.p.b. in their total daily ration.
- Poultry and swine are more sensitive to aflatoxin contamination. Under no circumstances should these livestock species be fed more than 20 p.p.b. aflatoxin in their daily rations.