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Feeding Oil to Horses: Choose WiselyBy Kentucky Equine Research Staff · March 23, 2016

Horse owners frequently reach for a jug of vegetable oil when they want to bump up energy consumption for weight gain or wish to add sheen to a coat. Faced with shelves upon shelves of choices, which is the best choice?

“All oils are 100% fat, so there is no difference in the number of calories each provides,” said Catherine Whitehouse, M.S., nutrition advisor for Kentucky Equine Research (KER). “Variations in the amount of omega-3 and omega-6 fatty acids exist among oils commonly fed to horses. These fatty acids are of particular interest to researchers because of their effect on inflammation and immunity, and because horses are not able to produce these fatty acids in the body, thereby counting on the diet to provide them.”

Cereal grains generally have far more omega-6s than omega-3s. A typical omega-3 to omega-6 ratio for cereal grains might be 1:10. Horses fed large grain meals, therefore, might have a skewed omega-3 to omega-6 ratio in the total diet, with omega-6s outpacing omega-3s.

For this reason, when choosing to add oil, it is best to select a product that contains more omega-3s. “Average omega composition of common oils include corn oil at 2:28, soybean oil at 1:6, and canola oil at 1:2, omega-3 to omega-6. For boosting calories and keeping omega balance in check, canola or soybean oil would be a far better choice than corn oil,” explained Whitehouse.

Fish oil has superior fatty acid content, with an omega-3 to omega-6 ratio of 6:1, but it is generally not fed to increase energy consumption. Rather, it is used in small amounts as a supplement that delivers the omega-3 fatty acids DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid) to moderate inflammatory and immune-related conditions. For this purpose, EO•3, developed by KER, is the go-to fish oil.

How much oil to offer any individual horse depends on the reason for feeding it. “Adding gloss to the hair coat might require as little as one-third to one-half cup (80-120 ml) of oil per day. On the opposite end of the spectrum, if the goal is to increase the calorie density of the ration, about 2 cups (500 ml) of oil per day might be fed,” said Whitehouse.

For top-dressing oils, an easy-to-follow recommendation would be to feed no more than 3.5 oz per 220 lb (100 ml per 100 kg) of body weight. A 1,200-lb (550-kg) horse would receive about 19 oz or just over 2 cups (550 ml) per day, split into two or three feedings.

“As with all new feedstuffs, horses should be slowly acclimated to oil, starting with one-quarter cup (60 ml) in a meal and then increasing by another one-quarter cup every week or so,” recommended Whitehouse. “This is a slower introduction schedule than some people use, but it allows the horse’s gastrointestinal tract to adapt to the fat, which will reduce the likelihood of soft manure, a typical, though usually transient, effect of using oil.”