Saddlebreds are trotting horses, with the natural ability to LEARN the rack and the slow gait, due to their gaited ancestors. The biggest influence in their development, however, were thoroughbreds, so they are primarily trotters. Their gaited side comes from the extinct Narrangansett pacers and a little bit of Standardbred later on.
The rare ones that are born truly "natural" gaited, in the way that Rocky Mountains, Tennessee Walkers, Icelandics, Pasos, etc. generally do not make Five Gaited Show horses.
In order for them to be selected to train for the gaits, they have to meet many requirements. So many are born that are not built for it, or would be better suited for other divisions that it just isn't worth the time to teach them.
Posted via Mobile Device