The Effects of Dry Period and Various Lactation Stages on Blood Na+ and K+ Concentrations in Holstein Cows

Normal physiological values of different blood parameters for various animals are influenced by a number of factors such as age, sex, breed, season, altitude, climatic conditions, nutrition and life habits of the species [4,6,9,19]. It has been reported that the significant differences (p < 0.001) in glucose, total lipid, cholesterol, total protein, uric acid and calcium levels were found between the dry period and lactation period of cows. [17]. In our other study, it was shown that leucocyte counts and mean corpuscular volumes (MCV) were not different in the lactation stages and dry period, and hemoglobin levels were similar in the lactation stages but lower in the dry period, and that haematocrit and erythrocyte counts were the highest in the third lactation period, and mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobine concentration (MCHC) were the lowest in the third lactation period [10]. It has been shown that the erythrocyte or whole blood potassium concentrations and erythrocyte or whole blood sodium concentrations and the sum of cation concentrations within erythrocytes remain relatively stable in both sheep and cattle kept under constant environmental conditions [1]. However, no comparative studies have been reported on the effect of lactation periods on erythrocyte and whole blood cation concentrations. The reports available on erythrocyte cation composition in dairy cows only show comparisons between those in late pregnancy and early lactation of dairy cows [3,16] or monthly variation in these cations in dairy cows [7]. It was suggested that the relationships has been observed between the erythrocyte parameARTICLE ORIGINAL