Concentration of serum electrolytes in Holstein cows at late pregnancy, parturition and post parturition periods

Blood samples were obtained for 85 Holstein cows in a dairy farm during two months prepartum, at parturition and two months postpartum. Measured electrolytes were sodium, potassium, chloride, calcium, inorganic phosphorus, magnesium and iron. At parturition, the level of chloride, calcium, inorganic phosphorus and iron was lower (P<0.05) than these values at other periods, whereas, concentration of magnesium was higher. No significant change was observed in serum sodium and potassium levels. The results indicate that the most important change in serum electrolytes is at parturition.