Influence of seasonal changes on the karyotype stability of Ukrainian Black and White dairy cows

Abstract

Of the total dairy cattle, 49 % belong to the Ukrainian black-and-white dairy breed. Animals are demanding to the conditions of detention, so the aim of the study was to study the impact of seasonal changes in the environment on the stability of the karyotype of cows of three age groups (first-born, adult and cows 8–10 years). The variability of the karyotype of the studied animals in different seasons of the year was manifested in the form of quantitative and structural disorders of chromosomes. Of the total dairy cattle, 49 % belong to the Ukrainian black-and-white dairy breed. Animals are demanding to the conditions of detention, so the aim of the study was to study the impact of seasonal changes in the environment on the stability of the karyotype of cows of three age groups (first-born, adult and cows 8–10 years). The variability of the karyotype of the studied animals in different seasons of the year was manifested in the form of quantitative and structural disorders of chromosomes. In primiparous women, the most pronounced genomic variability (aneuploidy) was observed in summer and winter and was 16.4 % and 8.8 %. In summer, this variability was more than twice the limit of spontaneous chromosomal variability. The highest percentage of structural chromosome abnormalities (chromosomal breaks) in cows of three age groups was observed in winter and was 2.5 %, 2.8 %, 3.0 %, respectively, and did not exceed the limit of spontaneous mutagenesis characteristic of cattle. An increased proportion of lymphocytes with a micronucleus in first-borns and cows aged 8–10 years (5.6 ‰, 6.4 ‰, respectively) was observed in the summer. The increased proportion of dinuclear lymphocytes appeared in the first-born in the summer season and amounted to 7.6 ‰ (at P > 0.99), and in cows 8–10 years, this variability in the summer season was 6.2 ‰, in winter – 6.7 ‰ with a statistically significant difference (P > 0.95) between the spontaneous level of cytogenetic variability. The association between karyotype stability of the studied animals and seasonal environmental factors was determined using a correlation coefficient (r). A significant positive correlation was found between aneuploidy and air temperature in primiparous and cows aged 8–10 years, relative humidity, precipitation and wind strength and chromosomal gaps in primiparous and adult cows, atmospheric pressure, relative humidity and asynchronous divergence. in adult cows and cows aged 8–10 years. A positive reliable associative dependence of the appearance of micronucleus lymphocytes and dinuclear lymphocytes on the amount of precipitation and wind strength in this area in primiparous and adult cows was established.