46 Pedigree tracing to determine origins of the Palomino Horse Breeders of America stock-type horse

Abstract

Registration numbers for the Palomino Horse Breeders of America (PHBA) have risen over the years due in part to new registration guidelines. In fact, PHBA has recently changed registration guidelines allowing registration of any horse with a palomino body color including those with unknown pedigrees. While this trend promotes registry growth, pedigree tracing can assist in documenting breed origins. Pedigree tracing is particularly valuable for color registries as the study of coat color patterns is a relatively new science plagued with misunderstandings due to pedigrees with inaccurate color designations. The objective of this study was to develop a better understanding of the historical origins of today's PHBA stock-type horse through pedigree tracing. 800 horses were randomly sampled from published entries from 10 years of the PHBA World Show. Only 460 of the 800 samples were utilized for this study due to the lack of verified documentation of extended pedigrees that included documented coat colors taken from the All-Breed Database. A complete record was defined as having an uninterrupted generation to generation inheritance pattern of a cream dilution gene influenced coat color from the sampled individual that directly traces back to the earliest existing recorded relative. Results indicate that a small number of foundation sires (Table 1) are responsible for the modern PHBA stock-type horse. The majority of horses within the Hall of Fame have pedigrees that trace back to only one of the sires identified in this study. Two of the identified sires have conflictsconcerning color designation and can be only identified as obligate cream gene carriers. While this study assists in documenting the origins of the breed, as PHBA continues to grow, additional genetic testing to accurately identify the cream gene within the horses registered may further support the goals of a color registry that is based upon horses with a cream phenotype.