The objective of this study was to examine conceptus development on Day 13 in ewes with estrous cycles of different durations. Ewes (n = 80) were screened according to the length of their estrous cycles. Subsequently, ewes that had either SHORT or LONG cycles were utilized (15.9 ± 0.1 or 18.6 ± 0.4 days; mean ± SEM, p < 0.01; 10 ewes per group). Jugular blood samples were collected twice daily from Days 0-6 after mating and then once a day until slaughter on Day 13. Concentrations of progesterone in plasma and amounts of ovine trophoblast protein-1 (oTP-1), protein, and prostaglandins (PG) E2 and F(2α)(PGF(2α)) in uterine flushings were determined. Concentrations of progesterone were greater (Day by treatment interaction, p < 0.01) on Days 2-4 for ewes in the SHORT group. On Day 5 and thereafter, progesterone concentrations were not different between groups. More (p < 0.05) oTP-1 and protein (8.1 ± 1.3 μg and 1.8 ± 0.3 μg versus 2.4 ± 1.3 μg and 0.8 ± 0.3 mg) were recovered from uterine flushings from ewes in the SHORT versus LONG groups, respectively. The ratio of PGE2:PGF(2α) was higher (p < 0.06) in flushings from ewes in the SHORT versus LONG group (1.4 ± 0.2 versus 0.9 ± 0.2, respectively). Conceptuses were classified by stage of morphological development. Conceptus development was accelerated (p < 0.01) in ewes of the SHORT group, as shown by filamentous conceptuses recovered from 78% versus 0% of SHORT versus LONG ewes, respectively. These data indicate that conceptus development and production of antiluteolytic signals occur sooner in ewes with shorter estrous cycles.
All Science Journal Classification (ASJC) codes
- Reproductive Medicine
- Cell Biology