Features of the karyotype of North Caucasus Ayrshire dairy cattle population: defects in reproductive functions

One of the ways of improving the genotypes of dairy cattle in Russia is to increase the proportion of the Ayrshire breed, which can be justly claimed to be one of the best dairy breeds in the world. However, due to the prevalence of large-scale breeding technologies, which involves the use of a limited contingent of dairy cattle bulls, including but not limited to the Ayrshire breed, the emergence of new-born calves with various anomalies, including chromosomal, which commonly have a hereditary basis attributable to gene mutations have been observed. Given that the bulk of these anomalies are acquired by recessive inheritance, they may not always manifest themselves in the phenotype and thus represent a hidden genetic load. In recent years, the significance of cytogenetic analysis and karyotyping is becoming increasingly important, not only when considering the theoretical assumptions, but also when solving applied problems aimed at preventing damage to agricultural production. This article presents the results of the cytogenetic analysis of Ayrshire cattle affected by reproductive problems. The following has been established: an absence of changes in the diploid set of the investigated dairy cattle (2n = 60); the presence of aberrant cells, whose frequency of occurrence amounted to 3.6% in the population of 440 head (number of aberrations per aberrant cell researched – 0.036 / 1.0); the absence of reciprocal translocations in the karyotype of the investigated population. It is suggested that the existing Ayrshire sires Hannulan Yaskiyri, Riihiviidan Urho Errant, O.R.Lihting and their descendants do not have a genetic load of chromosomal abnormalities