Genetic Characterization of Mangalarga Marchador Breed Horses Based on Microsatellite Molecular Markers

The Mangalarga Marchador (MM) horse breed has expressive importance in the Brazilian economy. Thus, the aim of this study was to investigate diversity in the MM breed. A database with a total of 3,193 genotyped horses was used (MM, n = 2,829; Andalusian - AND, n = 67; Pure Blood Lusitano - LUS, n = 43; English Thoroughbred - THO, n = 54; Arabian - ARA, n = 99; Campolina - CAM, n = 61; and Mangalarga - MAN, n = 40) for 13 microsatellite. Diversity parameters were estimates, such as mean number of alleles (Nm_a) and the number of rare alleles (AR), expected heterozygosity (He), F statistics, genetic distances, Hardy-Weinberg equilibrium test (HWE), population structure, and others. The Nm_a was 10.85, the AR was prevalent in the MM, and the He was 0.7402. In MM, the values of Fis (-0.0195), Fit (0.0566), Fst (0.0748), and deviations of HWE were observed. The genetic distances of the ARA and THO breeds with the other breeds were greater than the distances between the Brazilian breeds and between these and the breeds in the Iberian Peninsula. The population structure indicated that MM was substructured, yet there were some more genetically defined breeding farms. The genetic diversity is satisfactory for MM conservation, but the population is substructure, and parameters indicate moderate gene flow and the existence, though few, of crosses with other horse breeds. Immediate implementation of a genetic breeding program is required, especially seeking to conserve the structure of the MM breed as a well-defined genetic entity.