Many producers have turned to letting cattle graze corn fodder as a cattle feed amid record-setting drought. But a Purdue Extension animal scientist says there are certain precautions to take to keep animals healthy.
When hungry cattle are turned out on corn stalks with no prior rumen adaptation to starch, they can suffer acute acidosis - a sudden drop in rumen pH caused by rapid grain overload that can lead to illness or death.
"In the more seriously stressed, lower-yielding fields, some producers are reporting ear drop resulting from stalk quality issues and 'nubbin' ears that are slipping through the stripper plates of the combine head," Ron Lemenager said. "Collectively, this ear drop can create acute acidosis when grazing corn stalks if not managed correctly."
Part of that management is to scout fields before turning out cattle to determine how much corn is there.
"Cows seem to have a homing device, and they will find ears wherever they are in the field," Lemenager said.
If there is a lot of corn, he said producers could feed several pounds of corn grain per cow daily for several days before allowing them to graze. This helps adapt the rumen to starch.
Cattle also should be full of dry hay before turnout so they don't eat as many ears and should be turned out midday to allow corn stalks to dry from morning dew. Dry forage stimulates saliva production and can provide a bit of a rumen buffer to help minimize a sudden pH drop.
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Lemenager also suggested limiting grazing to smaller field sections.
"Consider strip grazing using a single hot wire to include only a portion of the acreage and make sure it includes a drinking water resource," he said. "This will prevent cows from gleaning the entire field of ears and will force them to consume leaves and shucks to dilute the intake of grain.
"After several days, the rumens should be adapted to starch and the concern of acidosis is reduced."
Even when properly managing livestock grazing on corn stalks for cattle feed, Lemenager advised that producers should still know the symptoms of acute acidosis. Cattle at first will look stressed or gaunt and could stop eating. Further along, they could have loose, gray stools and eventually might have elongated hoof growth.
"If cows are showing signs of stress, the best bet is to get them off of stalks and onto dry hay," he said. "But the key here is to prevent acute acidosis rather than try to treat it."
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