Abstract
The article presents the results of a study on the growth, development, and conformation characteristics of young cattle from two new breeding lines of the Kazakh White-headed cattle breed – Kunduz 9481 and Letchik 17433 – officially approved and included in the State Register of Breeding Achievements of the Republic of Kazakhstan. The research was conducted under the conditions of Ankatińskiy LLP in the West Kazakhstan region. The objects of the study were young animals (bull calves and heifers) of the Kazakh White-headed breed belonging to the breeding lines Kunduz 9481 and Letchik 17433. The growth and development of the offspring were studied based on appraisal (bonitation) data. Live weight was determined by weighing at birth and subsequently at 6, 12, and 15 months of age. Growth intensity was assessed by calculating the average daily live weight gain during the periods of 6-12, 12-15, and 6-15 months. Indicators of live weight, average daily gain, relative growth rate, and live weight increase coefficient at different age periods were analyzed. The exterior (conformation) characteristics of the young animals were also studied, as they are an important element in assessing the physical development and productive potential of beef cattle. The obtained body measurement indicators reflected the development of musculature and skeletal structure, making it possible to identify the genetic characteristics of the lines and serving as an additional criterion in selective breeding. It was established that animals of both lines are characterized by harmonious development, a pronounced beef type, and high growth intensity. At the same time, the descendants of the Kunduz 9481 line demonstrated advantages in a number of productive and conformation traits, including a larger and longer body type with well-defined beef forms, high heritability of productive traits, and stable uniformity in weight, conformation, and growth. The Letchik 17433 line is characterized by tall stature, a massive elongated body, high energy efficiency of growth, and stable transmission of beef and constitutional qualities to the offspring. The obtained results confirm the high genetic value and breeding potential of both lines and their prospects for the further improvement of beef cattle breeding in the Republic of Kazakhstan.