Сontribution of haplotypes in the formation of breeding and reproductive traits of animals
In recent decades, there have been serious problems with the reproductive function of cows. A number of lethal haplotypes associated with recessive disorders of reproduction and other signs were discovered. The frequency of harmful alleles carried by bull-sires increases in successive generations. A number of genome scanning methods have been developed to assess biodiversity within and between breeds. The obtained maps of disequilibrium linkage of genes with high resolution and the details of these maps made a great contribution to understanding the nature of the complex networks of connections between the haplotype genes and the formation of phenotypic traits. The development of a multi-allel calculation model made it possible to take into account the contribution of each haplotype as an additive and dominant variables for genomic evaluation and prediction of animal breeding traits. Mitochondrial DNA influences the traits of growth rate, product quality and fertility. The mtDNA haplotypes play an important role in the reproductive function of mammals during the stages of egg maturation, embryo development and the formation of productive traits in postnatal periods. Traces of introgression in the genome of modern breeds of animals, caused by artificial selection, manifest themselves in signs of complications of calving, defects in the constitution, feed utilization efficiency and fertility. The differences in non-equilibrium gene linkage between micro- and macro chromosomes in birds are explained by different recombination rates, and the differences in genotype differentiation are due to a higher mutation rate in micro chromosomes. The study of haplotypes in animal genomes is important for understanding the variations in their influence on the phenotype formation, on the etiology and pathogenesis of diseases. Thus, the genetic variability of the IL8 locus in cows is associated with the manifestation of interbreed and individual differences in immunity and resistance to infection. Detection and identification of ancestral haplotypes contribute to the analysis of the evolutionary dynamics of various populations, as well as to the identification of genomic regions for use in animal breeding.