Fat – usually in the form of vegetable oil – is commonly added to horse diets for a variety of reasons, and it pays to know more about oil to get maximum benefits for your horse.
Oil or fat? Both belong to a group of nutrients called ‘lipids’ and oil is used to describe liquid fat e.g. vegetable oil, whereas fat is used to describe solid fat e.g. animal fat (tallow or lard). Vegetable oils are used to supplement horse diets, mixed in compound feeds, in the form of oil-rich straights e.g. micronized linseed and rice bran, and poured directly onto a feed by the horse owner. Fish oils such as cod liver oil are still added to horse diets, most often for their beneficial effects on the joints.
Oils are the most energy-dense feeds available, supplying over twice the amount of energy per gram compared to grain carbohydrates. Pure vegetable oil does not contain any protein, carbohydrates or fibre, but does supply vitamins. Fish liver oils are rich in vitamins A and D; so much so that they cannot be used as a substantial source of energy because if you were to feed enough, you would give the horse toxic levels of vitamin A.
Natural horse diets tend to be around 4% oil, due to the relatively low amounts in forages including grass. A high fat horse diet tends to contain about 10% oil, which is actually a very low fat human diet. Because of this difference, the two cannot be directly compared. Horses seem to cope well with supplementary oil providing it is introduced into the diet gradually, and several research studies in the 1990s confirmed this fact.
In addition to calories, oils are a useful source of the two essential fatty acids, linolenic (omega-3) and linoleic (omega-6) acids. There is no evidence to suggest that even a low-fat forage diet is short of these essential fatty acids, but some horses seem to respond to supplementation. The balance of the two in the diet is believed to affect inflammatory processes in the body and an increased intake of the omega-3 fatty acids is believed to reduce inflammation. The ideal ratio of both (for humans) is between 1 and 4 to 1 omega-3 to omega-6. Forages are richer in omega-3 and grains are richer in omega-6. Linseed is the only vegetable oil commonly fed to horses which contains more omega-3 fatty acids than omega-6.
Linseed is the richest vegetable source of omega-3 fatty acids (alpha-linolenic acid), and is reputed to have benefits on the skin and hair as well as on inflammatory processes in the body. Fish liver oils are rich in the omega-3 fatty acids EPA and DHA; compounds that are made from alpha-linolenic acid in the body. There is evidence that these compounds are more effective in reducing joint inflammation than supplementary alpha-linolenic acid.
In next week’s blog we will explore the benefits of adding vegetable oils in variable amounts to your horse’s diet.