I recently made a trip to Florida horse country where I met a trainer and presented my business, he responded with something I have heard before; "the breed doesn't matter to me, I don't care about the breed". As a breeder, I know the breed does matter and not just because I breed Holsteiners. Different horses are configured for different types of work, Thoroughbreds are configured for forward, flat, fast movement. Quarter horses are bred to be quick for short distances and agile, necessary for herding work and quiet minds so as not to overreact to surroundings. Draft horses are big and heavy built for hauling equipment. Holsteiners were originally dual purposed work horses. They worked the fields, and also used for lighter carriage and riding purposes. They hauled plows through fields but because the area they worked in was mostly thick mud flats they developed a conformation that allowed them to have strong upward movement for pulling up their front and back legs out of the mud. They also had to have a lot of heart so as not to give up when pulling a plow through thick mud. As Germany progressed through the technological era the need for plow horses became obsolete. German breeders lightened up the plow horse by introducing outside blood thus creating an athletic and agile sport horse with a strong top lines with high rideablity necessary for jumping.
Next time you watch a video of a horse jumping slow it down and pay attention to every movement of the horse. Watch the front legs as the horse goes up over the jump, watch for evenness and quickness of the front legs. Watch the back legs as they progress through the jump. Some horses will open their hips and extend their hind legs behind them to clear the jumps, while others are not capable of this. They will merely tuck their hind legs underneath themselves. It's much like dog breeds, you wouldn't expect a herding dog to out run a greyhound. This doesn't mean a herding dog can't run it just means it's not built for sustained speed. It's not that a Thoroughbred can't jump, it is just limited in it's scope for todays sport of Show Jumping. Breed matters when it comes to the top of sport, and that is why I wouldn't bet my life savings on a Clydesdale winning the Triple Crown. When investing in a show jumper I put my trust with the breed with the most success at the upper levels of the sport with the least amount mares, the Holsteiner.