US farmers warned on feeding this year’s corn

09-11-2009 | |

Poultry and pig producers who don’t test the new corn crop before feeding it are taking a risk this year, said Purdue University experts. Due to wet harvest conditions mould in corn is present in much of the Midwest crop.

Brian Richert, Purdue Extension swine specialist, said a couple producers have started feeding new crop corn and had near 100% feed refusal because of the high vomitoxin levels in the corn.

“Those producers had to suck all that feed back out of the feeders, find a source of new feed and try to get feed back in for those animals,” he said. “It can cause some significant problems if producers don’t test their corn up front.”

Pigs will have reduced feed intake when deoxynivalenol (DON) levels are above 2 parts per mln and near complete feed refusal when DON levels are at 10 ppm or greater in the complete diet, Richert said.

Poultry less susceptible

On the poultry side of things, Todd Applegate, Purdue Extension poultry specialist, said not much is known about the ramifications of Diplodia, but poultry are not as sensitive as pigs are to the toxins produced by Giberella mould.

“From a nutritional standpoint, the lower test weights influence the corn kernel’s proportions of the germ versus endosperm, causing amino acid and energy shifts,” Applegate said when talking about Diplodia concerns. “If this is not accounted for during diet formulation, it could lead to decreased performance.”

Zearalenone, also found in Giberella infected corn, at fairly high concentrations – up to 800 parts per mln – may not cause any production impairments in laying hens, Applegate explained.

“However, part of the concern may lie in transference of those mycotoxins to the egg,” he said. “DON or vomitoxin is known to suppress the immune system in poultry, making them more susceptible to sickness. Levels of DON known to have these effects begin to occur at about 7.5 parts per mln, or less.”

Testing the crop

The experts say that farmers should test their corn before feeding it to the animals. When the results come back several questions can be asked:
– What are we going to feed as a dilution?
– How much can we feed?
– Do we have a source of clean corn where we can blend this down to an acceptable level that still provides the producer satisfactory performance with their livestock?
– Do we have to source other feed ingredients in to help with the blend down and cut the amount of high vomitoxin (DON) or zearalenone levels in corn?

Producers who have reproductive animals on their farm the corn should be specifically tested for zearalenone, a toxin that is produced by the mould Giberella.

“If levels are too high, above 3-5 ppm, it could impact the breeding herd,” Richert said. “Replacement gilts may not cycle and there could be problems getting sows bred.”

Diplodia, another mould that has been found widespread in this year’s US corn crop, can cause low test weights and is prone to shattering, which creates a lot of fine material, explained Richert.

Diplodia does not produce a known toxin and is safe to feed, but could throw off feed intake due to the mouldiness of corn, he said. Long-term shattering and fine material is a concern during storage, because they increase the susceptibility to other moulds including those that produce aflatoxin or ochratoxin.

To mask the taste some oil could be added to decrease dustiness of mouldy feed or molasses could be used for the same effects.

Mycotoxin binders

Another available option is mycotoxin binders or enzymes. Some agents can bind about 2-4 parts per mln of vomitoxin and there are only a few that are effective against vomitoxin or DON.

Clays and aluminum silicates do no work well for vomitoxin or DON. They work with aflatoxin, which is a completely different mycotoxin that is not of concern this year, the experts say.

Richert recommends producers to look at food preservative type-products or enzyme-specific products for vomitoxin. The enzyme products will cleave the toxin to make it less toxic to the animal.

The mycotoxin experts advice producers to talk with their feed company and nutritionist to look at performance test data for some of these compounds given what they’re dealing with, and find out which ones they support as having efficacy for that particular mycotoxin.

You can read more about mycotoxins in AllAboutFeed’s Mycotoxin dossier

Natalie Berkhout Freelance journalist