Effect of Oxytocin, Epinephrine and Atropine on the Oestrous Cycle of the Cow.

Oxytocin (100 U.S.P. Units) injected into heifers on Days 1 to 6 or Days 3 to 6 post-oestrum caused precocious oestrus. When 8 mg epinephrine hydrochloride or 50 mg atropine sulphate were superimposed on the oxytocin treatment, there was very little shortening of the oestrous cycle. Epinephrine or atropine administered on Days 3 to 6 post-oestrum did not materially alter the length of the oestrous cycle nor did administration of atropine during the latter part of the oestrous cycle.