Including higher levels of fat in horse feeds has gained attention recently. The benefits may include being able to increase the energy density of a ration without increasing the risk of colic or founder due to high carbohydrate levels and being able to increase performance by the glycogen sparing effect high fat rations appear to have. 15% appears to be an effective maximum.
Being able to increase the energy density of a ration by adding fat may have several benefits. In horses with high caloric requirements such as dressage horses, endurance horses, polo ponies and race horses, it may be difficult to meet the horse's energy requirements by adding carbohydrates without risking digestive disturbances such as colic, founder and azoturia. Adding fat to the ration at levels up to 15% may allow the energy requirement to be met at lower risk. Beyond 15%, there is some indication that the high fat in the ration may interfere with the absorption of fat soluble vitamins.
Increased energy density may also be of benefit to the older horse where digestion is less efficient or there are dental problems.
The effect of high fat rations on performance is being researched in a number of areas. There is some indication that high fat rations (up to 15%) may improve the performance of some horses when coupled with an appropriate conditioning program to allow the horse to use fat as an energy source more efficiently and prolong the amount of time the horse can perform at maximal level. Fat may also contribute to glycogen sparing by allowing the horse to use fat for maintenance activities. Fat levels beyond 15% do not appear to have a positive effect and may have a negative effect.
There is also some anecdotal evidence that the high fat ration has some calming influence on some horses.
The best source of fat appears to be corn oil with other vegetable oils having slightly lower efficiency. Properly treated animal fats may be used, but appear to have lower digestibility.
The total energy requirement of the horse and the exercise regimen of the horse needs to be carefully considered as the use of high fat rations are considered. The best ration for a horse is a total balanced ration which meets the horse's requirements for maintenance, growth, reproduction and work based on the individual horse.