Estrous and ovulatory responses following cervical artificial insemination in Thai-native goats given a new or once-used controlled internal drug release with human chorionic gonadotropin.

The study was conducted to compare estrous rate, ovulatory response, plasma progesterone concentrations, and conception rate following cervical artificial insemination in goats given a new or once-used controlled internal drug release (CIDR) device with human chorionic gonadotropin (hCG). Fifty-six Thai-native goats with the average age and body weight of 11 months and 17.3 kg received a 14-day treatment with a new CIDR device (Eazi-Breed(TM)CIDR®, Pfizer, NY, USA) or a once-used CIDR device. All goats received a 300-IU injection of hCG (Chorulon®, Intervet International B.V., New Zealand) at the day of CIDR removal to induce ovulation. All goats displaying signs of Estrous behavior were artificially inseminated at 12 h after the onset of estrus with frozen semen. No differences in percentage of estrus and ovulation rates were observed; however, goats that received once-used CIDR devices exhibited shorter (P < 0.05) duration of estrus in comparison with new devices (21.4 ± 1.4 h vs. 26.1 ± 1.1 h) and delayed the onset of estrus (47.0 ± 3.6 h vs. 36.5 ± 1.9 h) and the time of ovulation (74.9 ± 3.9 h vs. 64.5 ± 1.3 h), respectively. Progesterone (P4) concentrations were not significantly different (P > 0.05) between treatments during CIDR device insertion and at the time of CIDR removal except on day 4. No significant differences were found in overall conception rates between the treatments. This study indicates that the once-used CIDR device with hCG could be applied to synchronize the estrus and ovulation in small-size Thai-native goats without negative effects on Estrous behavior, ovulatory response, and plasma P4 concentration.