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Greenchopped corn to cover forage shortages

Eric Mousel Published on 30 June 2015

Some livestock producers find buying additional roughage is really not practical from a supply or cost perspective. Those producers may choose to chop a portion their corn to stretch out roughage supplies for a few months until other alternatives became available.

Greenchop versus silage

As many operators have discovered, it is important to differentiate between greenchopped corn and corn silage, because they are not the same thing. Greenchopping is harvesting fresh, green forage right out of the field at whatever moisture content the forage is at the time.

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In most situations where corn is greenchopped, moisture content will be 80 percent or more, leaving less than 20 percent dry matter. Conversely, silage is chopped at around 65 percent moisture to encourage the ensiling process for long-term preservation and storage of forage quality.

The bottom line is that when the moisture content of chopped forage is in excess of 80 percent, the forage will not effectively ensile.

Therefore, storing large quantities of greenchopped corn right out of the field will result in a lot of seepage, and ultimately spoilage, and the majority of your efforts will be wasted.

Although it should be noted, research from the University of Minnesota has demonstrated that greenchopped corn can be effectively stored in properly sealed silage bags, the cost of doing so likely is not very competitive.

Storage

So, can corn be greenchopped right out of the field and fed to livestock? Yes it can, but you won’t be able to store it in a pile for long periods of time like corn silage. My recommendation is to cut about two to three days’ worth of greenchop and feed that up before chopping more.

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Although not the best scenario in terms of labour and resource use, it likely is the best option available to limit the amount of greenchopped corn lost to spoilage. If you rely on a custom chopper, greenchopping corn is probably not going to be a practical solution for you.

Nitrates

Another scenario to be aware of involves nitrates. Producers will commonly greenchop corn because soil conditions are dry and either a complete loss of the crop is a possibility or roughage for livestock is not available.

Corn is a fairly effective nitrate accumulator, and this condition is intensified by dry soil conditions. Forage chopped with high nitrate concentrations (more than 2 percent nitrate-nitrogen) can lead to nitrate poisoning when fed to livestock.

Like most nitrate-accumulating plants, the highest concentrations of nitrate will be found in the lower one-third of the stalk. Therefore, corn-plant nitrate levels should be tested prior to greenchopping to determine the threat level for livestock.

Furthermore, raising the cutter bar on the chopper to 8 to 12 inches will substantially reduce nitrate concentration in the forage. Greenchopped corn that contains higher nitrate concentrations can be mixed with other roughages to reduce nitrate levels in the diet.

If nitrate levels are really high (more than 3 percent), talk to a ruminant nutritionist before feeding to make sure diets are effectively blended to reduce the threat of nitrate poisoning.

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Although the best use of corn for forage is silage because of its storage potential, greenchopped corn can be effectively managed to bridge the gap in your forage program.  PD

Eric Mousel
  • Eric Mousel

  • Extension Cow-Calf Educator
  • University of Minnesota
  • North Central Research and Outreach Center
  • Email Eric Mousel

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