Variation of 25-hydroxyvitamin D in sera of healthy and sick cows

Abstract

An interaction between the blood level of 25-OH Vit D, PTH, CT and the level of calcium, phosphorus and magnesium was examined in 182 cows which included healthy cows and cows with osteomalacia and paresis. The level of parathyroid hormone and calcitonin was determined using an IMMULITE analyser by means of immunometric assay. The level of vitamin D was measured using the enzyme linked immunosorbent assay (ELISA). The levels of calcium, phosphorus and magnesium were determined using an automate Eos-Bravo analyser with Hospitex reagents. The blood serum level of 25-OH Vit D varied from 18.1 to 56.4 nmol/l. In healthy cows it changed depending on age, the level of vitamin being statistically significantly lower and the level of CT higher in cows 2–4 years old compared with cows aged 8 years and over. The level of vitamin D negatively correlated with the level of calcium. The blood serum level of 25-OH Vit D changed in healthy cows depending on the season of the year: a statistically significantly higher level of the vitamin was found during the winter period as compared with summer. Preparations of vitamin D (injected 3–5 times) administered in the last days before calving changed the level of calcium, phosphorus, PTH and 25-OH Vit D. The blood serum level of PTH and 25-OH Vit D in cows with parturient paresis was statistically higher than in healthy cows. There was no correlation between calcium and PTH in the blood serum of cows with parturient paresis, although a strong negative correlation relation was found between calcium and 25-OH Vit D. The level of 25-OH Vit D in cows with osteomalacia (compared with healthy cows) did not differ statistically significantly. Keywords: cows, 25-OH vitamin D, parturient paresis, osteomalacia Abbreviations: 25-hydroxyvitamin D (25-OH Vit D), parathyroid hormone (PTH), calcitonin (CT), net energy for lactation (NEL)