The objectives of this study were 1) to determine the effects of adding a CIDR to the Ovsynch protocol on plasma concentrations of
estradiol-17β and
progesterone and conception in dairy cows with cystic
ovarian diseases and 2) to examine associations among the
estradiol-17β and
progesterone concentrations and conception. Cows were diagnosed as having cystic
ovarian diseases if they were found to have a cystic follicle (diameter ≥25 mm) without a corpus luteum by two palpations per rectum with an interval for 7 to 14 days. They were treated with either the Ovsynch (
GnRH on Day 0,
PGF(2α) on Day 7 and
GnRH on Day 9, with AI on Day 10; n=15) or Ovsynch+CIDR protocol (Ovsynch protocol plus a CIDR from Day 0 to Day 7; n=23). Plasma
estradiol-17β concentrations were determined on Days 0, 7 and 9, and plasma
progesterone concentrations were determined on Days 0, 7, 9 and 17. The plasma
estradiol-17β and
progesterone concentrations at all of the days examined and conception rates did not differ significantly between the two timed AI protocols. The
progesterone concentrations on Day 17 and conception rates were lower (P<0.05) for cows with low concentrations of
estradiol-17β (<2 pg/ml) on Day 9 than for cows with high concentrations of
estradiol-17β (≥2 pg/ml). The present study suggests that, in dairy cows with cystic
ovarian diseases, addition of a CIDR to the Ovsynch protocol had no remarkable effects on plasma
estradiol-17β and
progesterone concentrations during and after the treatments or on conception after timed AI. This study indicates that the low plasma
estradiol-17β concentration at the second administration of
GnRH in the protocols can be a predictor for impaired luteal formation and lower likelihood of pregnancy in dairy cows with cystic
ovarian diseases.