Abstract
The problem of increasing the number of sheep and mutton production in Kazakhstan is largely solved by fat-tailed meat and fat sheep breeding, therefore, one of the primary tasks of improving the meat-and-fat productivity of fat-fat sheep is to study the system of selection and use of animals, taking into account their age and size, in order to obtain from them the greatest amount of high-quality products. Science and practice have established that the production of mutton at the lowest cost of labor and money in meat and fat sheep farming is achieved by slaughtering young animals for meat in the first year of life. In order to study the growth and development characteristics of first-generation crossbred young animals obtained from crossing ewes of the Degeres breed with Edilbaev breed, the indicators of the exterior, growth and development of animals were studied. The assessment was carried out at birth, at the age of 4.5 months (at weaning) and at the age of 12 months. These indicators are important criteria for assessing the productive and breeding qualities of fat-tailed sheep. Based on the data of individual weighing of animals, the average daily increase in live weight and the growth intensity of young animals were determined. In addition, tissue samples from 10 different organs and tissues of the body were taken from 12-month-old crossbred sheep, in which the expression levels of the marker genes DGAT1, CAST, IGF-1 and POU1F1 associated with the productive qualities of animals were analyzed.