| Popis: |
In this study, three experiments were conducted to (1) evaluate estrus and ovulation synchronization using the short progesterone-CIDR or the medroxyprogesterone acetate (MAP) sponge protocol; (2) assess fertility after cervical insemination 8 or 4 h before the ovulation time; (3) evaluate the fertility of cervical artificial insemination or laparoscopic artificial insemination of ewes. The progesterone-CIDR protocol anticipated estrus (27.7 ± 5.8 vs. 43.1 ± 14.6) and ovulation (57.9 ± 3.9 vs. 80.0 ± 21.2) and improved estrus synchronization and ovulation compared with the ewes treated with intravaginal medroxyprogesterone acetate (MAP) sponges. Therefore, a progesterone-CIDR protocol was later used to evaluate fertility rates by cervical insemination with frozen semen at 50 or 54 hours after removal of the progesterone device, corresponding to 8 or 4 h, respectively, before the mean ovulation. However, the fertility rate did not differ between the two groups and was close to 20%. In contrast, laparoscopic insemination increased the fertility rate compared with cervical insemination (74.4% vs. 12.5%, P < 0.0001). Based on our findings, we conclude that using a short protocol with progesterone-CIDR improved estrus synchronization and ovulation in relation to using sponges containing MAP. However, using frozen semen for cervical artificial insemination near the time of ovulation using the progesterone CIDR protocol does not result in good fertility rates necessitating the use of laparoscopic insemination. |
