Q: My trainer suggested I add oil to my horse’s diet to help with her weight and coat. Does it matter what type of oil I choose? Are there certain benefits to feeding corn oil versus canola or vegetable oils?

A: Adding fat to a horse’s diet is a common choice when owners want to improve coat quality or weight gain because fatty acids coat the hair shaft, making it reflect light better so hair shines more and becomes more pliable. Fat also provides 2.25 times more calories to the diet than an equal weight of carbohydrates, which enables you to get more calories into the ration without having to greatly increase feed intake. The other benefit of using fat for weight gain is it is widely considered to be a “cooler” source of energy and less likely to make horses excitable than using higher-starch options.

On face value, the answer to the question of does it matter what type of fat/oil is used to improve coat quality or for weight gain, the answer is no. Corn, canola, vegetable, flax oil, etc., will all increase shine and add calories for weight gain. But there are some additional considerations to make because outside of their abilities to improve coat and increase condition, these fats have other effects within your horse’s body.

The composition of these fatty acids varies, with some containing more omega-6 fats while others contain more omega-3 fats. These differences are important to understand because these two types of polyunsaturated fats play key roles in cell membrane structure, inflammation, and other physiological processes.

The fat in a horse’s natural diet of fresh grass tends to be quite high in omega-3 fatty acids. However, these fats are not heat-stable, so much of the omega fat is lost when grass is dried to make hay. Many of the other common equine feed ingredients tend to be higher in omega-6 fats. This is especially true of high-fat ingredients such as rice bran and the vegetable oils used in feeds. This can result in a diet that provides more omega-6 than -3 fatty acids.

Both omega-3 and -6 fats are essential, meaning horses cannot generate them and, thus, must consume them in their diet. Because the level of omega-3 fats tends to be lower when horses do not have access to good-quality pasture, it is ideal to provide supplemental fats that are higher in omega-3 fats when trying to improve coat quality and body condition. This will not only improve coat quality and body condition but also help the horse better regulate inflammatory response.

Although corn oil is relatively cheap, it has no omega-3 fat, so I typically do not utilize it. Other oils often used for weight gain, where you may need to feed up to two cups a day, are soybean oil and canola oil because while these are both high in omega-6 fats, they do contain some omega-3. Better still, and my choices for coat-quality improvement, are flax or camelina oil because these have more omega-3 than -6. Coat quality might improve with as little as 2 fluid ounces a day. Their high cost could make them a more challenging option when larger amounts are needed for weight gain but, if cost is not a constraint, they would be a great choice for weight gain, as well.

Other good oil options are ahiflower oil, which is also high in omega-3 fatty acids including stearidonic acid. Hemp oil also contains stearidonic acid, in addition to an unusual omega-6 fatty acid, gamma-linolenic acid, which behaves like an omega-3.

Feeding any one of these oils will likely have a positive impact on coat quality and, if fed in enough quantity, weight gain, as well. Selecting an oil with higher omega-3 content might also have other added systemic benefits by regulating inflammation, which can help with joint health, respiratory function, immune function, and a number of other conditions.