Adding Fat to Horse Diets

Providing adequate energy to equine athletes and hard keepers can be a frustrating task. A horse can consume only so much forage and feed in a single day, so weight gain is sometimes uphill work. To safely elevate energy levels, fat is often added to rations. How that fat is delivered, however, was the focus of recent research.^*

As the name suggests, calcium salts of fatty acids (CSFAs) are created through the saponification of long-chain fatty acids, in this case those derived from palm oil, with calcium ions, resulting in calcium salts. CSFAs contain high levels of certain fatty acids, such as palmitic acid, stearic acid, oleic acid, and linoleic acid. Commonly fed to ruminants to enhance the energy density of a ration, CFSAs have not been studied extensively in horses.

The goal of this study, therefore, was to determine the influence of CSFAs compared to soybean oil on the digestibility of dry matter, neutral detergent fiber, acid detergent fiber, crude protein, crude fat, and gross energy.^* Fecal contents were collected from the cecum, through a cannula port. Volatile fatty acids and long-chain fatty acid concentrations were measured. Triglycerides and cholesterol were tested through blood sampling.

Researchers found no significant differences in the digestibility of CSFA compared to soybean oil, indicating the provision of soybean oil is a tried-and-true method of elevating calories in a ration.

Horse owners can increase the amount of fat in a diet in one of two ways:

1. Select a concentrate that contains high levels of fat. Fat is a go-to alternative energy source in many concentrates, particularly those intended for performance horses, senior horses, and those requiring low-starch diets. In these concentrates, fat is usually added through high-fat ingredients, such as stabilized rice bran (>20% fat) and vegetable oil (100% fat). Commercial fat-added concentrates typically contain 8-12% fat, with a few exceptions.
2. Top-dress traditional concentrates with stabilized rice bran or oil (canola, soybean). It is important that rice bran is stabilized, which means it has undergone specific processing that reduces the likelihood of spoilage.

As with all new feedstuffs, high-fat feeds and supplements should be gradually introduced into the diet. Depending on how much is fed, the transition period can last up to two weeks. If using oil, for instance, a conservative approach would be to feed 0.25 cup (60 ml) to each meal and then add an additional 0.25 (60 ml) cup every three or four days until you reach a maximum of 1 to 2 cups (240-475 ml) daily.

Horses fed high-fat diets should be supplemented with natural-source vitamin E  to offset oxidative degradation of lipids. Vitamin E serves as an effective whole-body antioxidant.

^*Fehlberg, L.K., J.M. Lattimer, C.I. Vahl, J.S. Drouillard, and T.L. Douthit. 2020. Digestibility of diets containing calcium salts of fatty acids or soybean oil in horses. Translational Animal Science 4(2).