Association of the DMRT3 nonsense mutation with performance in Coldblooded trotters

Abstract: In previous studies, a nonsense mutation in the gene doublesex and mab-3 related transcription factor 3 (DMRT3) was discovered to have a major influence on gait ability in horses. The mutation is permissive for the ability to perform alternate gaits, such as pace and tölt and has also been shown to have a favorable effect on speed capacity and harness racing performance in Coldblooded and Standardbred trotters. The main aim of this study was to investigate the association of the DMRT3 genotype with performance in Coldblooded trotters. A total of 769 Coldblooded trotters were genotyped for the DMRT3 mutation, where 485 had raced at least once and 284 were non-raced. The genotype was associated with harness racing performance (number of starts, victories, placings 1-3, earnings, earnings per start, unplaced, disqualifications, and race times). The performance traits were defined and obtained at different ages: 3 years, 3 to 6 years, and 7 to 10 years of age. At three years of age, the horses homozygous for the mutation (AA) earned more prize money compared to the horses homozygous for the wild-type allele (C). The performance results for the total career indicated that the genotype CA had better results for the majority of the traits, compared to horses homozygous for the wild-type allele (P<0.05). Horses with genotype CA also earned the most prize money for the total career (P<0.05). This study indicates that the heterozygotes at the DMRT3 gene have a favorable association with harness racing performance. The results from this study have practical implications for breeding and training, in which the information from this study could assist industry professionals in selecting the most ideal horse for breeding Coldblooded trotters.