estradiol-3-benzoate and Abortion--Veterinary

The objective was to compare three shortened protocols for timed-AI (TAI) on ovarian responses, pregnancy per AI (P/AI) and pregnancy loss after resynchronization of ovulation in multiparous Holstein cows. Cows (n = 370), at one location, were randomly assigned at non-pregnancy diagnosis (approximately 32 d after AI) to one of three ovulation resynchronization protocols. Cows in the OS group received a 5-d Ovsynch [100 μg GnRH on Day 1, 500 μg cloprostenol (PGF) on Days 6 and 7, GnRH on Day 8.5 and TAI on Day 9 (16 h after second GnRH)]. Cows in the OS + P4 (progesterone) group received a 5-d Ovsynch as described for OS group plus an intravaginal device (Cue-Mate), containing 1.56 g of progesterone (P4), between Days 1 and 6. Cows in the J-synch group received a Cue-Mate and 2.5 mg of estradiol benzoate (EB) on Day 0, PGF and Cue-Mate removal on Day 6, another PGF on Day 7, and 100 μg of GnRH on Day 8.5, with TAI on Day 9. Ovarian response and pregnancy status at 32 and 60 d after the resynchronization TAI were determined by transrectal ultrasonography. Blood samples were collected at first PGF treatment and at TAI from a subset of 40 cows per group to determine P4 concentrations. Percentage of cows with CL at initiation of the protocol did not differ (P > 0.05) among resynchronization groups. Plasma P4 concentrations at first PGF treatment were greater (P < 0.01) in cows that received a Cue-Mate (OS + P4 and J-synch) compared to OS cows. Luteal regression was greater (P < 0.01) for J-synch (88.6%) compared with OS (76.9%) and OS + P4 (78.8%). More (P < 0.01) cows in the OS + P4 and J-synch groups had their estrous cycle synchronized and were pregnant at 32 d after TAI (48.7 and 34.7%, 67.8 and 48.0%, and 72.4 and 50.0% for OS, OS + P4 and J-synch, respectively). However, more cows subjected to J-synch remained pregnant at 60 d after TAI and, hence, had fewer (P < 0.05) pregnancy losses (19.2, 18.8 and 5.0% for OS, OS + P4 and J-synch, respectively). In summary, cows resynchronized with either OS + P4 or J-synch had greater P4 concentrations at first PGF treatment and a greater response to treatments compared to cows subjected to OS. Although OS + P4 and J-synch resynchronization protocols resulted in increased P/AI at 32 d, pregnancy losses were significantly reduced in cows subjected to the J-synch protocol.

Topics: Abortion, Veterinary; Animals; Cattle; Estradiol; Estrus Synchronization; Female; Gonadotropin-Releasing Hormone; Insemination, Artificial; Ovulation; Ovulation Induction; Pregnancy; Progesterone; Progestins

The objective of this study was to compare a GnRH-based to an estrogen/progesterone (E2/P4)-based protocol for estrous cycle synchronization and fixed timed artificial insemination (TAI), both designed for synchronization of ovulation and to reduce the period from follicular emergence until ovulation in cows with a synchronized follicular wave. A total of 1,190 lactating Holstein cows (primiparous: n=685 and multiparous: n=505) yielding 26.5 ± 0.30 kg of milk/d at 177 ± 5.02 d in milk were randomly assigned to receive one of the following programs: 5-d Cosynch protocol [d -8: controlled internal drug release (CIDR) + GnRH; d -3: CIDR removal + PGF2α; d -2: PGF2α; d 0: TAI + GnRH] or E2/P4 protocol (d -10: CIDR + estradiol benzoate; d -3: PGF2α; d -2: CIDR removal + estradiol cypionate; d 0: TAI). Rectal temperature and circulating progesterone (P4) were measured on d -3, -2, 0 (TAI), and 7. The estrous cycle was considered to be synchronized when P4 was ≥ 1.0 ng/mL on d 7 in cows that had luteolysis (P4 ≤ 0.4 ng/mL on d 0). To evaluate the effects of heat stress, cows were classified by number of heat stress events: 0, 1, and 2-or-more measurements of elevated body temperature (≥ 39.1 °C). Pregnancy success (pregnancy per artificial insemination, P/AI) was determined at d 32 and 60 after TAI. The cows in the 5-d Cosynch protocol had increased circulating P4 at the time of PGF2α injection (2.66 ± 0.13 vs. 1.66 ± 0.13 ng/mL). The cows in the E2/P4 protocol were more likely to be detected in estrus (62.8 vs. 43.4%) compared with the cows in the 5-d Cosynch protocol, and expression of estrus improved P/AI in both treatments. The cows in the 5-d Cosynch protocol had greater percentage of synchronized estrous cycle (78.2%), compared with cows in the E2/P4 protocol (70.7%). On d 60, the E2/P4 protocol tended to improve P/AI (20.7 vs. 16.7%) and reduced pregnancy loss from 32 to 60 d (11.0 vs. 19.6%), compared with the 5-d Cosynch protocol. In cows withtheir estrous cycle synchronized, the E2/P4 protocol had greater P/AI (25.6 vs. 17.7%) on d 60 and lower pregnancy loss from 32 to 60 d (6.7 vs. 21.7%) compared with cows in the 5-d Cosynch protocol. Follicle diameter affected pregnancy loss from 32 to 60d only in the cows in the 5-d Cosynch protocol, with smaller follicles resulting in greater pregnancy loss. Pregnancy per AI at d 60 was different between protocols in the cows with 2 or more measurements of heat stress (5-d Cosynch=12.2% vs. E2/P4=22.8%), but not

Topics: Abortion, Veterinary; Animals; Body Temperature; Cattle; Contraceptive Agents; Dinoprost; Estradiol; Estrogens; Estrous Cycle; Estrus Synchronization; Female; Fertility; Gonadotropin-Releasing Hormone; Insemination, Artificial; Lactation; Ovarian Follicle; Ovulation; Oxytocics; Pregnancy; Progesterone