Genome Wide Association of Temperament Variation in the Tennessee Walking Horse

Temperament is a key criterion in the selection of horses for both leisure and competitive riding to ensure optimal performance and safety. The Tennessee Walking Horse (TWH) is described as a calm, docile breed and is often used as a trail, show, and pleasure horse. However, among horse owners and caretakers, there are anecdotes supporting familial and disciplinal typical behaviors and personalities. To investigate the contribution of genetics to temperament, a behavior questionnaire, gait information, and horse discipline were collected for 276 TWH as well as blood or hair samples for DNA. Factor analysis (FA) was conducted on the 20 item questionnaire for the set of 270 horses that met inclusion thresholds. FA identified five temperament factors in TWH: neophobia, trainability, dominance, independence, and watchfulness. These five factors account for 68.4% of the total trait variance. DNA from 116 TWHs were genotyped using the EquineSNP70 bead chip for three separate GWAs using the F1-‘neophobia’, F2-‘trainability’, and F3-‘dominance’ scores as the phenotype. Quantitative association analysis identified significant candidate loci for each factor.  Ongoing work includes identification of potentially functional polymorphisms and structural variants within these candidate regions from whole-genome sequences from the TWH.