Is the walk and trot efficiency a hereditary trait in primitive Konik Polski horses?

Background Performance testing is a critical tool for achieving genetic progress, yet its long-term effectiveness in primitive breeds under conservation programs is poorly documented. The Konik Polski horse breeding program aims to improve utility while preserving primitive characteristics. Methods This retrospective study analyzed a 25-year longitudinal dataset ( n = 1,608) from the official Field Performance Test to quantify genetic trends in gait efficiency, using nonparametric methods to assess the effects of test type, year, and age on stride length and speed at the walk and trot. To estimate heritability, a single-trait sire model and a linear mixed model were fitted. Results A significant positive trend was observed for walk stride length, which increased by approximately 10 cm under saddle and 19 cm in harness over the study period ( p < 0.001). In contrast, trot stride length showed high variability but no consistent trend, whereas trot speed declined. A strong negative correlation between trot stride length and trot time ( ρ = − 0.51) confirmed that longer strides were associated with faster movement, which is a desirable trait. The analysis revealed moderate heritability for walk stride length ( h 2 = 0.277). Genealogical line accounted for a negligible proportion of the total phenotypic variance for most traits, and age at testing did not significantly influence performance. Walk- and trot-related performance traits were not highly heritable in Konik Polski horses. Overall, the results indicate that the level of preparation is the most critical factor.