Today we will continue our discussion on equine grain associated disorders by looking more at the problems with feeding grain and advantages of feeding fat.  In a published review of this condition By Dr. David Kronfield from Virginia Tech and Dr. Pat Harris from Waltham, it is indicated that grain meals larger than 3 to 6 lbs at a feeding for an 1100 lb horse can lead to digestive disturbances and metabolic disorders.  Starch from grain is fermented in the cecum to lactic acid which can cause colic and diarrhea.  Lactic acid is also believed to be related to endotoxemia and founder.  Feeding grain causes an increase in plasma glucose and insulin and has been linked to the development of equine metabolic syndrome in some adults as well as developmental orthopedic disease in foals. 

The most common developmental orthopedic disease is osteochondritis desiccans and a larger response of glucose and insulin to a starch diet occurred in horses with osteochondritis desiccans fed a grain diet.  Cereal grains are excellent horse feeds, but their use must be limited.  

A portion of the energy can come from fats safer than from grain.  It takes about 3 weeks for a horse to accommodate to an increased fat diet.  More forage can be fed along with the fat and corn oil is an inexpensive source of fat.  We generally recommend decreasing the grain from a horse’s diet and gradually adding corn oil.  Corn oil can be added at 1 ounce twice daily and increased by 1 ounce every 5 days, up to 1 cupful twice daily at 1 month.  This alone will account for 20% of the digestible energy of an 1100 pound horse.  Although there is some concern about decreasing other essential nutrients in the diet by adding fat, this is not a problem as long as the ration is balanced and a normal ration of hay is fed with a small amount of grain.