Abstract
The article presents the results of research aimed at improving sheep productivity in the Republic of Kazakhstan through the effective use of genetic resources and reproductive crossbreeding. The objective of the study was to examine the live weight, exterior, and phenotypic characteristics of newborn lambs obtained from various breeding combinations in the farms "KH Bepen" (Abai region) and "LLP KH Aq Bas-Pavlodar" (Pavlodar region). A comparison was made between purebred and crossbred groups of animals in terms of live weight, wool yield, fertility rate, total lamb crop, and morphological parameters of newborns. The results of the research showed that the use of reproductive crossbreeding contributes to an increase in live weight and improvement of exterior traits in the offspring. Under the conditions of "Bepen," crossbred lambs (KMW×KFTCW) demonstrated an increase in birth weight by 0.85-0.59 kg compared to purebred counterparts, as well as a more harmonious body conformation. In the "LLP Ak Bas-Pavlodar" farm, the differences were less pronounced, indicating that the manifestation of heterosis depends on the combination of breeds and management conditions. It was established that the offspring from interbreed crossbreeding exhibited greater diversity in coat color and tail shape, reflecting the genetic influence of paternal lines. An analysis of body conformation indices revealed an advantage of crossbred lambs in terms of body length and chest indices, indicating better trunk and chest development. The obtained results confirm the effectiveness of reproductive crossbreeding as a means of enhancing meat and wool productivity in sheep and improving the exterior characteristics of young stock. The conducted research has practical significance for the further improvement of breeding and selection programs, optimization of breed composition, and the development of strategies to increase the economic efficiency of sheep farming in Kazakhstan.