Association of conformation and riding ability in Icelandic horses

The official breeding goal for the Icelandic horse promotes five-gaited horses with a functional and aesthetic conformation. The objectives of the present study were to assess the phenotypic and genetic relationship between standard conformational measurements and scores for riding ability. Further, to investigate if more detailed (3-D) morphometric measurements could discriminate between high-class and low-class horses based on scores for each gait. The data comprised records from standard conformational measurements and scores for the different gaits and the total score for riding ability of all assessed breeding horses in Iceland in 2000-2013 (10,091 horses). Further, records from a subpopulation of 98 haphazardly selected breeding horses that were subject to detailed quantification of the conformation in 3-D and genotyped with respect to DMRT3 genotype, were included in the study. Most of the standard measurements had a significant and curvilinear relationship with the studied riding ability traits. They had generally high estimated heritability but weak or moderate genetic correlation with the total score of riding ability. Proportions in the top line of the horse describing the height of the horse at front compared to hind were found to be most important for the riding ability, revealing the advantage of an uphill conformation. Their estimated heritability and genetic correlation with total score for riding ability designate them as important indicators for performance. Certain lengths, proportions and angles between bones in the fore- and hind limbs also had a significant effect on scores for some gaits. These results can improve the assessment of the conformation and consequently the riding ability of the Icelandic horse. (C) 2016 Elsevier B.V All rights reserved.