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How rain & snow impacts corn stalk nutrition

Whether grazing corn stalks or feeding corn stalk bales, nutritional value can be greatly impacted by the weather.

Winter has officially arrived in my corner of South Dakota with an icy and snowy front that socked our ranch and the surrounding area.

Fortunately, we made the decision before the storm hit to move the cow herd home from the cornfields where they had spent the last several weeks grazing.

Unfortunately, that means we are now officially dipping into our stockpile of forages and feeding hay. I fear the days of saving money on our feed bill by grazing crop residues are officially done for the season.

If you still have cattle on stalks, good for you! It’s a great way to save money, extend the grazing season, encourage exercise in late-gestating cows and fertilize the fields.

However, with inclement weather like rain and snow, it’s important to be mindful of the nutritional value of these feedstuffs and adjust your supplement program accordingly.

Bruce Anderson, University of Nebraska-Lincoln Extension forage specialist, recently addressed how weather can impact corn stalk quality.

Anderson writes, “Fall rainfall, and even snow, is good for wheat and next year’s crops, but it does have its drawbacks. One challenge is rain’s impact on corn stalk feed quality.”

Rain reduces corn stalk quality several ways, he says. Most easily noticed is how fast stalks get soiled or trampled into the ground when fields are muddy.

“Less noticeable are nutritional changes. Heavy rain soaks into dry corn stalk residue and leaches out some of the soluble nutrients. Most serious is the loss of sugars and other energy-dense nutrients, which lowers the total digestible nutrients (TDN) or energy value of the stalks.  These same nutrients also disappear if stalks begin to mold or rot in the field or especially in the bale. Then palatability and intake also decline.

There is little you can do to prevent these losses. What you can do, though, is begin to supplement a little earlier than usual, Anderson suggests.  

“Since weathering by rain reduces TDN more than it reduces protein, consider the energy value of your supplements as well as its protein content. Weathered corn stalks still are economical feeds. Just supplement them accordingly.”

If your cattle are home for the winter like mine are, another consideration is knowing the nutritional value of your corn stalk bales. Anderson addresses the feed value of cornstalk bales.

He says, “Before you feed those bales, first find out what they have to offer nutritionally. Sample and test your bales as soon as possible so when snow gets deep or other feeds run out, you will already know how to best feed your corn stalk bales.

“Test those corn stalk bales for nitrates, of course, to make sure to feed them safely. And while you're at it, also test them for protein and energy.”

Anderson says he’s seen test results from a number of corn stalk bales. “You may be surprised at how variable the protein and energy content were in these bales. I've seen protein as low as 3% and as high as 6%.

“Since dry pregnant cows need 7-8% protein in their diet, those high protein bales will need only a little protein to adequately care for the cows. But those 3% bales will need quite a bit of supplement to keep cows in good condition.

“Use a protein supplement that is nearly all natural and is mostly rumen degradable. Maintenance-level forage diets need degradable protein for the rumen microbes, but remember that urea and other non-protein nitrogen sources aren't used as well.”

Most bales had pretty good TDN levels, often close to 55%. Cows fed these bales should do very well up until calving with just corn stalk bales and adequate protein supplement, he says.

“However, some stalks were rained on before baling and were below 50% TDN. Cows fed these lower quality bales will need some extra energy, too. Drought-stressed corn that was put up as hay may have higher energy and protein values depending upon the stage of maturity of the plant.”

At our place, we are 45 days away from the start of our calving season, so maintaining body condition scores and a steady plane of nutrition will be critical from now until after calving season. Knowing the nutritional value of the feed is certainly a good place to start, and if your herd is still on stalks, be sure to supplement accordingly to avoid deficiencies.

The opinions of Amanda Radke are not necessarily those of beefmagazine.com or Farm Progress.

TAGS: Ranching Feed
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