Thoroughbred Breeding: The Requirement for Natural Service

Question
I'm a teaching assistant at Iowa State in the animal science department and I'm putting together a horse lecture.  Can you tell me the history of why Thoroughbreds have to be bred by natural service instead of AI in order to be registered?  Thank you!!

Answer
hi -- the thoroughbred horses all have registration papers and a lip tattoo and when being bred they must follow all of the rules for producing a registered  foal out of a registered mare and bred by a registered stud.all of the foal papers are on file in the jockey club in N.Y. this keeps the breeding on the up and up and keeps the horse breeders buying at the sales. thanks ED HESS