Selenium content in feed and cows blood serum in the central-eastern Poland

The work aimed at determining to what degree cattle herds were threatened with selenium deficiency on the basis of the concentration of this element in soil, feeds, and the blood serum of dry and lactating cows (in the 2nd, 4th, and 6th week of drying, and in the 2nd, 4th, and 6th week of lactation, respectively). The analysis of cow's body supply with selenium showed that selected dairy cattle farms in the Central-Eastern Poland were threatened with the deficiency of this element. Moderate hyposelenosis was found in the herds, whose state was requiring feed supplementation with selenium. Selenium concentration in cows' serum depended on the animal physiological condition, as well as the selenium concentration in soil and feeds, that the animals had received. An increase in the selenium level, amounting to 214.4, 226.0, and 260.8 nmol∙dm⁻³ in blood sampled in the 2nd, 4th, and 6th week of cows' drying off respectively, was recorded. An opposite relation was observed in lactating cows, in which during successive lactation weeks, decreasing selenium concentration in the blood serum (amounting to 250.9, 241.5, and 220.3 nmol∙dm⁻³, respectively) was oberved.