Drying Corn Can Lock Away Its Feed Energy

One of the risks involved with using Ontario’s 2009 corn crop for poultry is the amount of drying required. It might have destroyed enzymes, and some protein and energy might be bonded to each other and not available to poultry.

That’s according to Dr. Mike Leslie, poultry nutritionist for Masterfeeds, at a producer update meeting here recently. The higher the drying temperature, the greater the degree of bonding, he said.

However, there are enzymes that can be purchased as additives to break those bonds.

Much of the harvest was also light on bushel weights, he said, particularly east of Toronto and north of a line from Guelph to Stratford and west to the lake.

The lightweight corn will have less energy. Feed mills can compensate by blending with heavier-weight corn or by discounting the price.

There are logistics challenges to keep Grade 3 corn (54 or more pounds per bushel) and Grade 5 (50 lbs. or less) in separate bins, he said. There’s also the challenge of making sure staff draws from the right bin to make feed.

Compounding that situation is sometimes needing to segregate feed ingredients according to toxin levels.

Pigs can tolerate no more than two ppm (parts per million); turkeys are quite tolerant and can consume up to six ppm. Broilers can handle toxins better than layers and broiler breeding flocks, which are kept longer and thus consume more feed and are more prone to having their immune systems compromised by the toxins.

So far there has been enough Grade 3 corn in Ontario to meet demand, Leslie said, but if it runs short, the price gap with Grade 5, which is plentiful, will widen. In other words, rations made of only Grade 3 corn will carry a higher price premium.

There is a lot of toxin in the corn from some parts of the U. S., he said, and the toxins in corn from the southern U. S. tends to be more difficult to deal with.

This is an issue that feed mills can’t avoid simply by refusing to buy U. S. corn, or first testing the corn when they’re shopping, he said, explaining that ethanol plants may be buying U. S. corn and the toxins will show up in their DDGs (dried distillers grains). The process triples parts per million.

Other byproducts where toxins are concentrated are wheat shorts and middlings.

Corn grading is not precise for bushel weights. For example, Grade 5 corn could be anywhere from 48 to 51 lbs. per bushel, he said. And bushel weights can vary from farm to farm, so mills have to keep on top of what they’re grinding to ensure there’s enough energy in the ration.

EXPENSIVE TESTING

The most accurate test for toxins, he said, is too expensive – $100,000 for the equipment and $100 per test – so most of the testing is simpler, faster and less expensive.

But it’s also less accurate. The ELISA and colorimetric tests that most mills use are calibrated to results from more expensive HPLC equipment, he said.

Feed mills start the season with a lot of testing to determine what type of crop is coming in from farmers, then they develop their strategies for the rest of the season, he said.

For example, strategies for a “bad” toxin year will be quite different from the 2009 harvest which was a good one in terms of toxin levels.

In dealing with this year’s bushel-weight challenge, some mills might choose to go with Grade 5 corn and price poultry rations low; others might choose to exclusively use Grade 3 and will need to price their rations higher. Others will blend the two grades.

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