Abstract
The aim of the study was to evaluate the effect of planned mating based on the targeted selection of breeding stallions and mares on the growth and development of young horses of the Mugalzhar breed and Kazakh horses of the Jabe type. The studies were conducted under year-round herd grazing conditions at the horse-breeding farms LLP “Akshiman-Agro”, LLP Agrofirm “Akzhar Ondiris”, and PF “ANARA”. The research material included body measurements and live weight indicators of parent horses and fillies obtained from planned mating from 3 days to 18 months of age. The growth and development of young horses were assessed using generally accepted zootechnical methods followed by statistical analysis. It was established that the parent animals were characterized by harmonious body conformation and sufficiently high live weight. The live weight of breeding stallions ranged from 511.0 to 543.0 kg, while that of mares ranged from 482.8 to 499.7 kg. The offspring obtained from planned mating demonstrated stable age-related growth dynamics without signs of exterior disproportions. The live weight of fillies increased from 42.8–43.7 kg at 3 days of age to 324.3–332.1 kg at 18 months. At the same time, height at the withers increased from 88.4–89.6 cm to 136.9–138.7 cm, chest girth from 80.2–80.9 cm to 159.9–164.1 cm, and cannon bone circumference from 11.2–11.3 cm to 17.0–17.2 cm, respectively. The most intensive growth rates were observed between 1 and 6 months of age, when the live weight reached 158.0–200.7 kg. A clear relationship was identified between the parameters of the parent stock and the growth indicators of the offspring, confirming the effectiveness of targeted animal selection in planned mating. The results confirm the effectiveness of planned mating for improving productive and adaptive traits in herd horses.