Chronic oxytocin treatment in cows reduces spontaneous milk ejection after withdrawal. The objective of this study was to test the sensitivity of the mammaiy gland to oxytocin after a short milking interval, that is, when the udder was relatively empty. Moreover, the effect of occasional i.m, oxytocin injection (50 IU) on the oxytocin blood pattern was tested. I.m. oxytocin injection caused a long lasting of oxytocin blood levels (at least for 2 h) and prolonged myoepithelial contraction Chronic oxytocin treatment obviously reduces contractibility of myoepithelial cells in the mammary gland at a normal physiological level of oxytocin release.
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