Influences of manual udder stimulation and oxytocin on mammary artery blood flow in lactating cows
Houvenaghel, A.; Peeters, G.; Verschooten, F.
Archives Internationales de Pharmacodynamie et de Therapie 205(1): 124-133
1973
ISSN/ISBN: 0003-9780 PMID: 4796579 Document Number: 70176
A flowprobe was implanted around the mammary artery of one half of the udder of 7 lactating cows, to measure changes in blood flow through the udder half. Hand milking or massage of the udder with either a cloth immersed in water at 40 deg C or oil at 20 deg C normally induced a distinct increase in blood flow that continued throughout the whole period of stimulation. Intravenous injection of physiological doses of oxytocin (100-500 mU) increased the blood flow after a 20-50 s latent period, and the increase continued for 36-200 s. During milking, the increase sometimes even preceded the moment of milk ejection. Milking the implanted udder half was generally more effective in increasing blood flow than was milking the other half of the udder. It is concluded that the flow increase during milking is provoked partly by oxytocin and partly by a non-hormonal mechanism.