Abstract
The Mugalzhar horse breed holds significant value for meat production in Kazakhstan. Developed through targeted selection, the new Irtysh stud type demonstrates outstanding adaptation and productivity, with stallions reaching an average live weight of 486.1 kg and mares 463.4 kg, an increase of up to 73 kg compared to the original group. The coefficient of variation for live weight and metacarpus girth is higher in the Irtysh type (1.34-1.26 in stallions, 3.78-3.26 in mares), supporting efficient selective breeding. Statistically significant differences in body measurements and live weight (P > 0.99) and strong correlations between key traits (r = 0.20-0.49) highlight the effectiveness of selection for meat productivity. Importantly, SNP analysis of the LCORL gene revealed that the CT genotype is most frequent and is significantly associated with increased withers height, body length, chest girth, metacarpus girth, and body weight (P < 0.05). These findings suggest that LCORL can serve as a useful molecular marker for improving growth and productive traits in the Mugalzhar breed. The combination of genetic and phenotypic selection in this population provides a practical basis for further economic gains in horse meat production.