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Grazing Stalks Can Present Problems

published: November 19th 2008
by: Bruce Anderson, extension forage special
source: bigwire.com

Extra grain left behind by the combine can be a bonus for cattle grazing corn stalks, but too much grain can cause health problems.

Any time more than about eight bushels of grain per acre is left in the field after harvest, grazing cattle risk getting acidosis and founder. Both diseases are caused by excessive grain intake, which increases rumen acid production. This can cause severe foot and hoof problems, including lameness. While smut is not a health problem, some grain may contain other molds that can produce mycotoxins. Vomitoxin and fumonisin rarely cause problems for beef cattle at typical contamination levels; however, aflatoxin may be more of a concern this year. If you suspect mycotoxin may be present, assay the grain to determine the extent of the potential problem.

Estimate the amount of corn down in a field. An 8-inch ear of corn contains about one-half pound of corn grain so it takes 112, 8-inch ears to equal 1 bushel (1 bushel = 56 pounds). Thus, by counting the number of ears, the amount of corn can be estimated. For corn planted in 30-inch rows, count the number of ears in three 100-foot furrow strips and divide by two to give an approximate number of bushels per acre. Count small and broken ears as half ears and count extra large ears as one and one-half ears. Any amount beyond eight bushels per acre will require a well-planned grazing strategy.

One strategy for using high-grain cornstalk fields is to minimize availability of grain to susceptible animals. A good way to do this is to first graze yearling cattle, calves, or cull cows destined for slaughter, then follow with cows. Another alternative is to graze only a few hours per day. You also could strip graze the field to force cows to consume some husks and leaves along with the ears of corn. A final strategy might be to feed some grain or ear-corn seven to ten days before cattle are turned out to help them adapt to a high-grain field.

One factor influencing the success of these strategies is the experience level of the cattle grazing the field. Old cows with previous experience in cornstalk fields can pick up amazingly high amounts of corn in a short time, as can experienced yearling cattle. If they have not been conditioned to eating a high grain diet, some of the previously listed strategies may fail. Inexperienced calves may actually have the least risk of founder or acidosis in high-grain cornstalk fields because they must first learn how to find corn. As a result, their grain intake increases gradually and safely.