Acute Effect of 9α-Fluoroprednisolone Acetate (9α FFA) on Blood Leukocytes and Somatic Cell Content of Milk

Lactating Holstein cows received 0 (saline), 5, or 10 mg 9a FFA immediately following morning milking.Thereafter blood samples were collected hourly until completion of the evening milking 10 hours later.Treatment with 9a FFA resulted in a linear increase in plasma glucose during post-treatment (P < 0.05).Total leukocytes in blood increased linearly (P < 0.05) with time following 5 or 10 mg 9a FFA but not after saline.This increase could be attributed primarily to an increase in blood neutrophils.Treatment with 9a FFA decreased (P < 0.05) blood eosinophils but it did not alter numbers of lymphocytes or monocytes.Both 5 and 10 mg 9a FFA reduced milk yield at 10 and 24 hours post-treatment (P < 0.01) but differences attributed to dose were not significant (P > 0.10).Direct microscopic measurements of somatic cell content of fore, primary and residual milk revealed no significant (P > 0.10) effect of 9a FFA on number of total somatic cells, granulocytes, agranulocytes, or epithelial cells.These results suggest that corticoid-induced leukocytosis of blood is not reflected by increased somatic cell numbers in milk.