Abstract
This study aimed to determine whether reproductive performance of ewes submitted to laparoscopic timed artificial insemination (TAI) would be similar to ante meridiem (AM)/post meridiem (PM) rule and assisted natural mating (NM), and whether GnRH may enhance the pregnancy rate in TAI. In experiment I, 191 non-lactating ewes were synchronized, then TAI was performed either 48h after progesterone (P4) removal (TAI-48h) or 12h after estrus detection (AM/PM); moreover, some ewes were submitted to NM (NM) as control treatment. In experiment II, 247 non-lactating ewes were allocated in five treatments, a control (no-GnRH on protocol) and four treatments arranged in a factorial design 2×2. The factors were time and dose of GnRH: ewes that received either 10μg (TAI-10μg-36h) or 25μg of GnRH (TAI-25μg-36h) 36h after P4 removal and ewes that received either 10μg (TAI-10μg-48h) or 25μg of GnRH (TAI-25μg-48h) at time of insemination, 48h after P4 removal. In experiment I, pregnancy rate in TAI-48h was lower (P=0.03) than AM/PM and NM. Moreover, the probability of pregnancy in TAI-48h was higher (P=0.06) in ewes detected in estrus early. In experiment II, the use of GnRH in TAI protocols increased (P<0.01) pregnancy rate at synchronization, and TAI-25μ-48h and TAI-10μg-36h treatments increased (P=0.02) pregnancy rate compered to TAI-10μg-48h. We conclude that TAI decreased pregnancy rate compered to NM and AM/PM, which may be improved by GnRH use in TAI to synchronize ovulation.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.