A CIDR-based timed AI protocol can be effectively used for dairy cows with follicular cysts

The present study evaluated whether a controlled internal drug release (CIDR)-based timed AI (TAI) protocol could be used as an efficient tool for the treatment of ovarian follicular cysts in lactating dairy cows. In the first experiment, lactating dairy cows diagnosed with follicular cysts were randomly assigned to two treatments: (1) a single injection of GnRH at diagnosis (Day 0) and AI at estrus (AIE) within 21 days (GnRH group, n = 70), or (2) insertion of a CIDR device containing progesterone and an injection of GnRH on Day 0, PGF2α injection at the time of CIDR removal on Day 7, GnRH injection on Day 9, and TAI 16 h after the GnRH injection (CIDR-based TAI group, n = 65). Conception rate after the CIDR-based TAI protocol (52.3%) was greater (P < 0.05) than that after AIE following a single GnRH injection (26.9%). In the second experiment, lactating dairy cows diagnosed with follicular cysts (Cyst group, n = 16) and cows having normal estrous cycles (CYC group, n = 15) received the same treatment: a CIDR device containing progesterone and an injection of GnRH on Day 0, PGF2α injection at the time of CIDR removal on Day 7, and GnRH injection on Day 9. The proportion of cows with follicular wave emergence and the interval from treatment to follicular wave emergence did not differ (P > 0.05) between groups. The mean diameters of dominant follicles on Days 4 and 7 as well as preovulatory follicles on Day 9, and the synchrony of ovulation following the second injection of GnRH did not differ (P > 0.05) between groups. These data suggest that the CIDR-based TAI protocol results in an acceptable conception rate in dairy cows with follicular cysts.