Luteal function and blastocyst development were compared in ewes treated with GnRH (100 μg) on Day 1 (Day 0 = day of estrus) or in ewes previously induced into estrus with PGF2α. In Experiment 1, the duration of estrous cycles of ewes previously treated with PGF2α were longer (P<0.06) than those that received PGF2α plus GnRH, GnRH alone, or remained untreated (control) ewes. Progesterone concentrations were lower (P<0.07) on Day 1 and higher (P<0.01) on Days 16 and 17 of the estrous cycles following PGF2α treatment relative to those of the natural (control) cycles. In Experiment 2, blastocysts of ewes treated with PGF2α were less developed (P<0.06) by Day 13 of pregnancy than those of the control ewes. The GnRH treatment did not influence any of these characteristics. Treatment with PGF2α delayed luteal formation during the subsequent estrous cycle, increased the duration of the estrous cycle and slowed the rate of blastocyst development relative to GnRH-treated and untreated ewes.
ASJC Scopus subject areas
- Animal Science and Zoology