Influence of blood serum selenium on udder health in dairy cows

Abstract

The aim of this study was to determine the effect of selenium concentration in early lactation on mammary gland health and histological characteristics of the udder. The experiment included 30 high-yielding Holstein-Friesian cows. Selenium concentrations in blood and milk serum, and the average somatic cell count in the first and sixth months of lactation were analyzed. After exclusion of the experimental cows from the herd, histological characteristics of the udder were examined (the degree of leukocyte infiltration and the number of granulomas in the parenchyma). The mean selenium concentration in the blood serum was 0.62±0.11 mmol/L and that in the milk serum was 0.12±0.07 mmol/L. Optimal blood levels of selenium were found in 19 cows and suboptimal levels in 11 cows. A significant negative correlation was observed between blood and milk selenium concentrations and somatic cell count in early and mid lactation. There was no relationship between blood selenium concentration, milk selenium concentration and the amount of milk produced. Selenium-deficient cows had a significantly higher milk somatic cell count in early and mid lactation and significantly lower levels of selenium in milk. Upon histological analysis, 120 samples of individual quarters of the udder were grouped according to the degree of leukocyte infiltration and number of granulomas. Results showed that an increase in the degree of leukocyte infiltration and number of granulomas leads to an increase in the proportion of quarters from selenium-deficient cows and a decline in the percentage of quarters from cows exhibiting normal blood selenium concentrations. Selenium has a significant impact on udder health. Changes caused by selenium deficiency occur due to marked inflammation process in the mammary gland.