Effects of CIDR and eCG with estradiol-17β or estradiol cypionate on the follicular wave emergence synchronization in seasonally anestrous ewes

Abstract

Estrous, hormonal, and ovarian responses in anestrous ewes treated with different synchronization treatments were evaluated. Fourteen Texel ewes received controlled-internal-drug-releasing devices (CIDR) on Day -12 and eCG on Day 0. Animals received 350 μg estradiol-17β (E2; n=5), 350 μg estradiol cypionate (ECP350; n=4), or 70 μg ECP (ECP70; n=5) on Day -6. Mean E2 and FSH concentrations fluctuated during 48 h after E2/ECP (P<0.05). Only one ECP70 ewe did not exhibit estrus. Estrous and ovulation features, follicular wave emergence synchrony, number of CL, and LH, FSH, P4 and most E2 patterns, in E2 and ECP70 ewes were similar (P>0.05). Follicular wave emerged earlier in E2 than ECP70 ewes (P<0.05). No ECP350 ewes ovulated by 7 days after eCG. Mean P4 concentrations increased until 7 days after ovulation (P<0.001). Three E2 and two ECP70 ewes became pregnant. Perhaps E2 can be replaced with ECP70 in the CIDR-E2-eCG anestrous ewe synchronization protocol.