Genetic Parameters and Inbreeding Effect of Morphological Traits in Sardinian Anglo Arab Horse

SIMPLE SUMMARY: Cannon bone circumference, chest girth, shoulder length, and withers height are important biometric measures that are useful to describe the horse’s body conformation correctly. It is interesting to observe how these traits are connected to each other and how they are used to improve the genetic progress of the breed. The percentages of Thoroughbred and Arabian blood were also estimated for each horse in the pedigree population, to evaluate how the conformation might be modified thanks to different breeding purposes such as: racing, jumping, and other equestrian disciplines. The results show that the improvement of the Arabian blood determined a depressive effect on the studied traits; on the contrary, when the Thoroughbred blood percentage increases, the measures of the studied traits increase too. The trait most affected by the variation of the two blood percentages was withers height. It has been demonstrated that the conformation is related to sporting results, soundness, and durability and that body and legs shape are highly heritable. At this purpose, it might be useful, to restart the body measurements collection and to match them with the horse’s performance at races. ABSTRACT: The purpose of this study was to estimate the heritability and genetic correlations of four biometric measurements and an overall score (OS) in the Sardinian Anglo-Arab horse (SAA); moreover, the effect of inbreeding on these traits was investigated. A dataset with 43,624 horses (27,052 females and 16,572 males) was provided by the Agricultural Research Agency of Sardinia (AGRIS). Cannon bone circumference (BC), chest girth (CG), shoulder length (SL), and withers height (WH) were measured on 6033 SAA horses born in Sardinia between 1967 and 2005; beside the measurements, an overall score (OS) was taken comparing the morphology of each horse to an “ideal type” that is scored out of 100. The mean value is 20.5 cm for BC, 185.9 cm for CG, 67.6 cm for SL, 160.8 cm for WH, and 73.2 for the OS. The heritability estimates ranged from 0.78 to 0.23. The results allow to foresee high genetic progress through the breeding programs. The most affected trait by the inbreeding rate seems to only be the withers height.