Influence of oxytocin infusion during oestrus and the early luteal phase on progesterone secretion and the establishment of pregnancy in ewes

摘要

Summary. In Experiment 1, an osmotic minipump containing oxytocin was implanted s.c. in ewes for 12 days beginning on Day 10 of the oestrous cycle, producing ～ 100 pg oxytocin/ml in the plasma. Two days after the start of infusion, all ewes were injected with 100 μg cloprostenol and placed with a fertile ram. At slaughter 22 days later, 9 (75%) of the 12 control (saline-infused) ewes were pregnant compared with 1 (11%) of the 9 ewes infused with oxytocin. In the control group, midcycle plasma concentrations of oxytocin were significantly higher in nonpregnant than in pregnant ewes.