Interbreed differences in the content and variability of cholesterol in cattle of Siberia

The purpose of the study was to assess interbreed differences in the content and variability of the level of total cholesterol in the blood serum of cattle bred in Siberia. The level of cholesterol in cows of the 2nd-3rd lactation of the Holstein, Red Steppe and Kholmogory breeds bred in the Novosibirsk and Kemerovo Regions and in the Republic of Sakha (Yakutia) was studied. Cholesterol concentration was determined by enzymatic colorimetric method. Data were pre-evaluated using the Shapiro-Wilk test and QQ-Plots. The Kruskal-Wallace test was used to establish differences between unrelated groups. For multiple comparison, Dunn's posterior test with Holm's correction was used. η2 was used as a test to assess the magnitude of the effect. According to the concentration of total cholesterol in the blood serum, the ranked series of breeds is as follows: Holstein → Red Steppe → Kholmogory, the medians were 5.25, 4.1 and 2.89 mmol/l, respectively. Interbreed differences in cholesterol content among animals of the studied breeds were established (H = 15.83, df = 2, p = 0.0003644). The observed effect size η2 was 0.19, which reflects a rather large difference between the means and indicates the contribution of the breed factor to the hereditary component of the cholesterol level in cattle. The revealed interbreed differences are manifested in a lower content of total cholesterol in cows of the Kholmogory breed in comparison with animals of the red steppe (Z = 3.83, df = 2, p = 0.0001306) and Holstein (Z = 3.83, df = 2, p = 0.0001306) breeds.