[Effect of synthetic hormones of the neurohypophysis on the mammary glands of sheep].

The influence of intravenous injection of various doses of synthetic oxytocin, arginine-vasopressin and lysine-vasopressin on intramammary pressure of ewes was tested. A single injection caused a short-term intramammary pressure increase. The intramammary pressure curves for the tested hormones were similar. However, big doses of oxytocin resulted in a different type of response, consisting in successive contractions of decreasing magnitude. A positive relationship between lg oxytocin doses and intramammary pressure at doses from 10 to 100 mU was shown. This relationship for arginine-vasopressin was at 200 to 500 mU, and that of lysine-vasopressin at 200 to 1 000 mU. The latency period between the moment of hormone injections and the rise in intramammary pressure decreased when bigger doses were used. The milk-ejection activity of arginine-vasopressin was only 14,5% of oxytocin activity. The activity of lysine-vasopressin was 10,2% respectively.