Why is corn bad for horses in the winter?

Corn isn't really bad for horses. There are many rumors surrounding corn saying that it is bad to feed it to them for many reasons, but for the most part the rumors are not true. There are however some rules you should go by when feeding corn, never feed more than 3 pounds at one time and usually never more than 4 to 6 pounds a day. The horse should always have access to clean water and the bulk of the diet should be made up of grass or hay. The only downside to feeding corn is that it makes a horse 'hot' temperament wise (not heat wise) and if fed in winter when the horse is not being worked as much it can cause behavioural problems from excess energy.