There are several reasons for a horse to go "off feed" or stop eating. Is the horse sick? Does the horse have an elevated temperature? The teeth and mouth should be checked. A sore tongue or bad teeth are often common causes of decreased feed intake. Boredom may be a cause that may be overcome with exercise. Nutrient deficiencies can also affect intake. Limited roughage intake may create a potassium deficiency. Changing from a grass hay to alfalfa hay may entice a horse to eat. If a horse has been stabled and/or kept in a drylot, green grass will often stimulate appetite.