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Test Maize for Moulds Before Feeding, Urge Experts

by 5m Editor
2 November 2009, at 10:51am

US - Pork and poultry producers who do not test the new corn crop before using it for feed are taking a risk this year, says an expert at Purdue University, and mould in corn is present in much of the Midwest, including Indiana.

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

He said: "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. 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 two parts per million and almost complete feed refusal when DON levels are at 10 ppm or greater in the complete diet, Dr Richert said.

On the poultry side, Todd Applegate, Purdue Extension poultry specialist, said not much is known about the ramifications of Diplodia, but poultry are not as sensitive as hogs 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," Dr Applegate said 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 concentrations up to 800 parts per million – may not cause any production impairments in laying hens, Dr Applegate said.

He explained: "However, part of the concern may lie in transference of those mycotoxins to the egg. 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 million, or less."

De Richert said producers have a couple of options to consider.

"If the corn is not harvested yet and you are not going to get to it for a week or two because of soybean harvest, you can walk the field and take a representative sample, shell it and send it in to the Indiana Animal Disease Diagnostic Lab at Purdue or to a grain company for a mycotoxin analysis," he said. "If you are harvesting corn but can buy a little time by feeding old crop corn or purchasing feed for livestock, that will give you time to get your corn in a bin and test it."

Once in the bin, there could be a dilution effect, and producers should take multiple core samples to blend before sending it in for analysis.

"Once you know what you have, then you can manage it," Dr Richert said.

After getting the test results back, producers should ask questions such as:

  • What are we going to feed as a dilution?
  • How much can we feed?
  • Do we have a source of clean corn to blend this down to an acceptable level that still provides satisfactory performance? and
  • Do we have to source other feed ingredients to help with the blend down and cut the amount of vomitoxin (DON) or zearalenone levels in corn?

For producers who have reproductive animals on their farm, Dr Richert recommends having the corn tested specifically for zearalenone, a toxin that is produced by the mould, Giberella.

"If levels are too high, above three to five parts per million, it could impact the breeding herd," Dr Richert said. "Replacement gilts may not cycle, and there could be problems getting sows bred."

Diplodia, another mould that has been widespread in this year's corn crop, can cause low test weights and is prone to shattering, which creates a lot of fine material, Dr Richert said. 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 it increases susceptibility to other moulds, including those that produce aflatoxin or ochratoxin.

Producers may need to look at options available to change the palatability and mask the taste with flavouring agents for Diplodia-infected corn, he said.

"Some oil could be added to decrease the dustiness of the mouldy feed and increase palatability," Dr Richert said. "Molasses could also be added to reduce dustiness and partially cover these mouldy off-flavours."

Another available option is mycotoxin binders or enzymes.

"We can bind about two to four parts per million of vomitoxin with some binding agents," Dr Richert said. "There are only a few that are effective against vomitoxin or DON. The clays and aluminum silicates do not work well for vomitoxin or DON. They work with aflatoxin, which is a completely different mycotoxin that is not of concern this year."

Dr Richert recommends producers 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.

"Different toxins have different requirements for those compounds, and we have to be careful what we put into those diets," Dr Richert said. "They may or may not help us."

Producers should talk with their feed company and nutritionist to look at performance test data for some of these compounds and find out which ones they support as having efficacy for that particular mycotoxin, he added.