The effect of the milking process on oxytocic activity in the blood plasma of cows during oestrous.

The purpose of this work was to compare the oxytocic activity of plasma in oestrous cows during milking and for the first and second days following oestrous. Oxytocic activity of blood plasma was measured by the in vitro rat mammary cube assay of van Dongen and Hays. During oestrous, signigicantly lower amounts of oxytocin are released into the bloodstream of cows following milking as compared with the control values.