Application of different degrees of inbreeding in sheep breeding.

Abstract

The article presents the results of research aimed at improving selection methods for Karakul sheep of the Kazakh intrabreed type with a bronze-colored sur (gray) fleece pattern. Based on these findings, the study explores the application of different degrees of inbreeding within linebreeding to accelerate the breeding process. Research methods included determining the animals' kinship using pedigree records, insemination and lambing journals, and lamb evaluation logs. To ensure the accuracy of kinship data for selected sheep, close attention was paid to maintaining precise pedigree documentation on the farm. A summary of the inheritance patterns of bronze coloration under homogeneous selection showed that the degree of inbreeding in genotypes does not affect the heritability of the selected trait. Uniformity is identified as a key breeding trait in colored Karakul sheep, characterized by consistent distribution of fleece roughness across all lamb types. According to the newly developed methods, the degree of inbreeding may help stabilize the genetic potential of Karakul sheep breeding in the Atyrau region. Intraline selection is based on identifying and using the best individuals within a line; therefore, traits primarily determined by additive polygenic action-i.e., those with high heritability-can be improved through such methods. For traits with low heritability, family selection with progeny performance evaluation is necessary. Linebreeding may involve both related (inbreeding) and unrelated matings. Inbreeding is used to increase the frequency of desirable genes and to enhance organism homozygosity. It is applied to fix outstanding traits of specific individuals within a developing line, particularly in the initial stages of line formation. When high homozygosity is achieved through close inbreeding, such lines are referred to as inbred lines. In breeding and pedigree work, linebreeding of sheep with leading fleece colors using an inbreeding coefficient of F = 25% has proven effective. In such cases, expression of traits increased by 8.46%, while in outbred animals, the increase was 14.8%.