Effect of different intravaginal devices in estrus synchronization and pregnancy rate in woolless sheep submitted to FTAI via superficial cervical with fresh chilled semen

Abstract

The aim of this study was to evaluate the effect of different intravaginal devices in estrus synchronization and pregnancy rate in woolless sheep submitted to FTAI via superficial cervical with fresh chilled semen. Forty crossbreed ewes were used and randomly distributed into two groups: Group 1, ewes treated with the device CIDR^®; Group 2, ewes treated with sponges impregnated with 60 mg of medroxyprogesterone acetate (MAP). The devices remained in the animals for 14 days and the TFAI via superficial cervical was performed 55 h after the devices were removed. The TFAI was performed using fresh chilled semen from rams with proven fertility. The average interval between the end of treatment and the onset of estrus was 29 ± 0.59 h (CIDR^®) and 34 ± 2.7 h (MAP), showing a significant anticipation (P < 0.05) at the onset of the estrus in animals treated with CIDR^®, in comparison to MAP. The pregnancy rate and prolificity was 80% and 1.8 in the group of sheep treated with sponges with MAP and 25% and 1.6 for the CIDR^®. Once the high number of animals in estrus in the CIDR^® group did not result in
perfect synchronization, resulting in low pregnancy rate, it is recommended the use of sponges impregnated with MAP for TFAI in woolless ewes, 55 h after the intravaginal device removal.