Impact of the Thoroughbred horse breed on the development of the Bulgarian sport horse breed

Abstract. The Bulgarian sport horse (BSH) is a newly recognized breed selected entirely for equestrian sports (show jumping, dressage, and eventing). Thoroughbred stallions were widely used in the breeding process during the first stage of the development of the new breed. As in many other half-blooded horse breeds, the Thoroughbred horse is a well-recognized breed used in the process of development to improve stamina and movements. The aim of this study was to analyze the genealogical structure of the BSH and to trace the sire lines of Thoroughbred stallions as well as the family (mare) lines descending from the mares of the Thoroughbred breed. The research covers the period 1970–2018 and includes all horses enrolled in the three completed volumes of the Studbook of the breed. The information was provided by the “Bulgarian Sport Horse Association. As a result, four sire lines were determined, including 51 stallions, and three families were established representing 26 mares. The population of the newly approved horse breed (BSH) has a well-developed genealogical structure owing to the consistent and correctly conducted selection process during the nearly 60-year period of its creation. Despite the great interest of breeders and athletes involved in equestrian sports to use more and more stallions from the famous European riding breeds as sires, the Thoroughbred breed should be included in the breeding process through the method of “blood-infusion”.