As the horse can store the fat-soluble vitamins, why should there be a daily supply ? Fat-soluble vitamins (A, D, E, K) can be given in relatively large amounts infrequently because body stores can be replenished. Although it takes a certain time to deplete good stores of fat-soluble vitamins they should not be allowed to run too low. The longest interval between supplies should be four weeks. However this is not an efficient way to supply vitamins; daily supplies are more economic and keep the horse at a peak of metabolic efficiency rather than continuously changing the systems from rapid build-up to a slow breakdown of reserves and then build-up again.