Corn Oil in Equine Diets

Corn oil has been a staple in the diets of many horses for years, but has this much-loved additive fallen out of favor? Supplementing a horse’s diet with corn oil has its advantages and disadvantages, but scientific headway might be making this pour-on less appealing to horse owners.

Because it is completely fat, corn oil was originally added to diets to increase the energy density without increasing bulk. Studies have shown that that regular supplementation of fat as an energy source has a glycogen-sparing effect and has been found to be beneficial in long-distance exercise. With regard to intense exercise, however, corn oil resulted in increased lactic acid production and higher heart rates in comparison to horses supplemented with rice bran (approximately 20% fat).

The use of corn oil as an energy source is particularly valuable in the hot months of the year because its digestion produces less heat than any other energy constituent in a horse’s diet.

Corn oil cannot be used as the only energy source. It should never be fed at more than 15% of the total diet, but 1 to 16 ounces per day is safe.  Too much oil will decrease feed consumption and may cause loose manure. If large amounts of oil are fed too quickly, horses may experience bloating and excessive gas production, so oil should be introduced slowly, adding a little more each day.

Digestibility of corn oil is high, which means that the horse, once its gastrointestinal tract adapts to the oil, is able to utilize almost all of the oil with no waste. Corn oil remains the most palatable oil in taste tests, with no other oil or oil combination ever topping it. Because it is a liquid, it adds no bulk and is therefore helpful for horses that have to consume large amounts of feed.  Corn oil attracts loose particles and keeps down the dust in a feed, making it an excellent choice for horses with respiratory problems or for those that consume powdered supplements.

Horses fed corn oil have improved coat quality and shine, and an improvement in the flexibility of the hooves has been noted. Further, studies on corn oil supplementation have shown its effect on decreasing reactivity, which is why it has been touted as “calm energy.”

Perhaps the biggest failing of corn oil and the reason for its decline in popularity, is the high omega-6 and low omega-3 content, which has been found to promote inflammatory processes in the body. When added to a diet composed entirely of hay and grain, corn oil can grossly imbalance the omega-6 to omega-3 ratio, which makes tissues vulnerable to inflammation.

Many of the benefits of using corn oil are similar for other vegetable oils like canola or soybean oil, but the other oils have better omega-6 to omega-3 ratios. In the end, will the health benefits of balancing omegas overcome the definite taste preference in the quest for the ideal oil for horses?