Estimation of genetic parameters of body conformation and racing performance traits in Yili horses.

The Yili horse is a riding-type breed that has been continuously bred independently in China. The genetics of body conformation and racing performance traits need to be comprehensively considered in making breeding decisions. This study is the first to estimate the genetic parameters of 13 body conformation and racing performance traits in Yili horses using a linear model. In total, 9937 body conformation and 2576 race records of 9100 Yili horses obtained from 1993 to 2022 were reviewed. The results showed that heritability estimates of body measurement traits were medium to high, ranging from 0.334 (cannon bone perimeter, CP) to 0.720 (withers height, WH), whereas heritability of the linear scale traits were low to medium, ranging from 0.080 (body length score, BLS) to 0.245 (overall score, OS). The heritability of racing performance traits was low to medium, ranging from 0.054 (racing time, RT) to 0.347 (average speed, AS), but there was a high level of repeatability, ranging from 0.341 (ranking score, RS) to 0.604 (AS). Notably, high genetic correlations were estimated among body measurement (0.588 on average) and racing performance traits (0.924 on average). Overall, body measurement traits and racing performance traits were highly influenced by genetics, had high potential for selection. These findings confirm the possibility of carrying out an evaluation program of Yili horses. We are also continuing to track and evaluate the performance of Yili horses and provide research ideas and methodologies for genetic evaluation of other local horse breeds.