Corn-stubble fields provide a cost-effective winter-grazing opportunity in a year of drought-induced feed shortages, but managers should take precautions to avoid acidosis that can occur when hungry cattle consume too much starch. This sudden drop in rumen pH 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,” Purdue University Extension animal scientist Ron Lemenager says. “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 says. If stubble fields contain substantial quantities of grain, he suggests feeding 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. Turning cattle out at midday allows 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.
Lemenager also suggests 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 says. “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 on stalks, cattle become better adapted to starch and the risk of acidosis declines, but even so, Lemenager says, producers should 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 says. “But the key here is to prevent acute acidosis, rather than try to treat it.”