Comparison of hormonal changes of estrous cycle with cytology of cervical mucosa and hematological parameters in dairy heifers

Cervical mucosa cytology and hematological parameters in heifers were determined during different phases of the estrous cycle. Ten healthy Holstein heifers were synchronized by two injections of PGF_2α at 14 days interval. Blood and cervical mucosa samples were collected at days of 0, 2, 10 and 19 of estrous cycle. Differential cell counts were performed, and the progesterone level was measured by radioimmunoassay. Progesterone levels in diestrus and the percentages of neutrophils in metestrus were shown to be higher than in other phases of the estrous cycle (P<0.05). In contrast, the percentages of epithelial cells in metestrus were lower than other phases (P<0.05). A difference was also seen (P<0.05) in blood progesterone levels between four estrous cycle phases. However, there was no significant difference in RBCs, hemoglobin, hematocrit, WBCs, neutrophils, lymphocytes, monocytes, and eosinophils between four estrous cycle phases. Hormonal changes in different phases of estrous cycle affect neutrophil presence in cervical mucosa. It is important to consider cervical cytology and hormonal assay together for evaluation of dairy cow reproductive tract function.