Hematological changes of dairy cows in postpartum period and early pregnancy

In this experiment, 50 postpartum healthy Holstein Frisian dairy cows were selected from a large commercial dairy farm. They had normal parturition and had no postpartum problems. The calving number of cows was one to four, and they were inseminated 60 days after parturition. There were no clinical signs of endometritis when cows were examined during routine visits for monitoring fertility. The criteria for selection were that they had a normal parturition history and had calved 25 to 30 days before. They had no mucopurulent discharge from vulva or abnormality in rectal palpation. The cows were evaluated on days 25 to 30 and days 50 to 60 postparturition. Blood samples were collected on sampling days from the coccygeal vein. Hematological parameters were measured by the routine procedures. The health of all uteruses was confirmed by the cytological evaluation of cervical mucosa smear. Cytological samples were obtained from the discharge of cervical mucus and uterine fluid. The concentration of progesterone in serum was measured by radioimmunoassay. There were significant differences in packed cell volume (PCV) between the 25–30 days postpartum, the 55–60 days postpartum, and the pregnant cows. The hematocrit level in the pregnant cows was significantly higher than that in postpartum cows (P < 0.05). The leukocyte count and hemoglobin concentration in the pregnant cows were significantly higher than that in postpartum cows in 25–30 days after parturition. The erythrocyte count in pregnant cows was significantly higher than that of postpartum cows in 55–60 days after parturition. There were significant differences in PCV and hemoglobin in 25–30 and 55–60 days after parturition with the progesterone level of >1 and <1 ng/mL. Hematocrit and hemoglobin concentration in pregnant cows were, respectively, significantly higher than that in postpartum cows with different levels of progesterone (P < 0.05). There were significant differences in segmented neutrophils in the clinically healthy and affected cows by the subclinical endometritis in 25–30 days after parturition. In cows with subclinical endometritis, the percentage and absolute number of segmented neutrophils were significantly higher than in the clinically healthy cows (P < 0.05). There were no significant differences between cows which get pregnant with one and two to three times artificial insemination (P > 0.05).