EFFECT OF MILKING ON LEUCOCYTES IN SUBCUTANEOUS ABDOMINAL VEIN OF COW

Leucocyte counts were made before, after, and five minutes after milking to determine if milking caused a leucopenia in the subcutaneous abdominal vein of the cow. Fifty cows were machine milked, 20 were milked by teat cannulation, and 30 were not milked but sampled according to their usual milking times. Leucocyte counts for machine-milked cows averaged 7,874, 7,406, and 7,389 cells/mm3, for the three sampling times; cannulated cows averaged 8,715, 8,845, and 8,850 cells/mm3; and nonmilked controls averaged 7,910, 7,785, and 7,980 cells/mm3. Erythrocyte counts tended to increase for all three groups, but plasma protein concentration remained the same. Therefore, the leucocyte decrease for machine-milked cows was interpreted as a response to machine milking and not a result of hemodilution. When blood samples were collected simultaneously from the subcutaneous abdominal and jugular veins of machine-milked cows, leucocytes decreased in the subcutaneous abdominal vein but not in the jugular vein. This suggests that the leucopenia was effected locally and not systemically. © 1969, American Dairy Science Association. All rights reserved.