Correlation Analysis Between Stride Characteristics and Racing Ability of 2-year-old Yili Horses in Track Conditions

In this study, we aimed to explore correlations among stride characteristics, time records, and bonus amounts to identify relevant indices for evaluating racing abilities of 2-year-old Yili horses. In total, 41 and 26 Yili horses were enrolled in the 1600 and 3600 m races, respectively. This experiment was performed by measuring their stride characteristics using a high-speed video and collecting time records during the competition and the bonus amounts. The results showed that the 2-year-old Yili horses' stride length (SL), stride frequency (SF), middle SL (mid SL), hind limb SL (hind SL), forelimb SL (fore SL), aerial duration SL (AD SL), stride angle, and advanced placement (AP) between the leading hind limb and trailing forelimb (AP LH-TF) were significantly and positively correlated with the bonus (P < .01). The bonus group had significantly higher values for these variables than the nonbonus group (P < .05); the stance duration and the overlap between LH and TF (overlap LH-TF) were negatively correlated with the bonus (P < .01), and the bonus group had a significantly lower overlap LH-TF value than the non-bonus group (P < .01). These findings indicated that 2-year-old Yili horses with greater SL, SF, mid SL, fore SL, AD SL, and stride angle values have better racing abilities. Likewise, smaller stance and overlap LH-TF values correspond to better horse racing abilities. The swing trailing hind limb, mid SL, AP LH-TF, and SF were filtrated by stepwise regression analysis as the primary indices for evaluating the racing ability of 2-year-old Yili horses.