Plasma progesterone and LH concentrations in ewes after injection of an analogue of prostaglandin F-2

Abstract

Plasma progesterone and LH [luteinizing hormone] concentrations were monitored throughout a natural estrous cycle in 12 Clun Forest ewes and compared to those following treatment with a single i.m. injection of 100 .mu.g ICI 80,996 [16-aryloxyprostaglandin], an analogue of prostaglandin F-2.alpha., given during the luteal phase of the cycle. After injection of the analogue there was a high degree of synchrony in the return of estrus (44.0 .+-. 1.9 h; mean .+-. SEM) and the timing of the LH peak (48.5 .+-. 2.0 h) from injection. There were no significant differences in the plasma progesterone concentrations or in the height and duration of the preovulatory LH peak between control and treatment cycles. The technique offers the possibility of controlled ovulation in the ewe.