Is there any harm in giving horses corn stalks or ear corn?
Old-timers fed ear corn to horses after the fall harvest to help them keep weight on through the winter. In general, horses find the corn palatable, first eating the kernels and later chewing on the cob.
In some countries, like Peru, the whole corn plant is chopped and fed to horses fresh, especially in areas where there is a shortage of grazing. Corn silage is fed in some parts of Northern Europe as well, particularly during times when horses are not allowed out on the pastures. These practices were also fairly commonplace in the past in the United States but have fallen out of favor over the past few decades. The reason is fairly simple: it is easier to go to the local feed store and purchase a bag of fully fortified, nutritionally sound horse feed and bales of good-quality hay.
The risk of horses getting sick from the ear corn or the stalks is too great for many horse owners. Ear corn and stalks might harbor mycotoxins produced by molds (Fusarium spp.) that develop when the corn plant is grown under adverse weather conditions. The mycotoxin fumonisin seems to be the most devastating to horses, causing equine leukoencephalomalacia (also known as moldy corn poisoning or blind staggers), which brings about facial paralysis, ataxia, and potentially death. Risks with feeding corn silage also include bacterial contamination, such as Clostridium botulinum which causes botulism, and Listeria moncytogenes, which causes listeriosis.
Mold and bacteria are rarely visible on the exterior of the ear or stalk, making it nearly impossible to detect a potential problem. There does appear to be a variation in the susceptibility to these poisonings among individuals, so not every horse is equally affected when exposed. If the growing conditions are ideal for the corn plant and the harvest is properly stored, corn plant products can be a nutritious addition to a horse's diet when used with caution and moderation.
Learn more about corn here:
Moldy Corn a Risky Ingredient for Horses