cloprostenol and lecirelin

This is the very first report that suggests high pregnancy rates can be obtained with use of the Doublesynch protocol in anestrous dairy cows. Recently, a new synchronization method has been developed (Doublesynch) that resulted in synchronized ovulations both after the first and second gonadotropin-releasing hormone (GnRH) treatments. It was suggested that this protocol has the potential to increase the pregnancy rates in primiparous dairy cows. The aim of the current study was to confirm the success of the Doublesynch protocol and further to investigate the effect of this method on pregnancy rates in anestrous cows. Lactating primiparous Holstein (Bos taurus) cows (n=165) between 60 and 172 d postpartum were monitored twice with 10-d intervals (on Days -10 and 0) by ultrasonography, and blood samples were collected. Cows were classified as anestrous if both blood samples had progesterone (P4) concentration <1 ng/mL and as cyclic if at least one of the two samples had P4 concentration >or=1 ng/mL. Cyclic cows were classified again as cyclic-high P4 (having an active corpus luteum) if the second blood samples had P4 concentrations >or=1 ng/mL and as cyclic-low P4 if P4 concentrations were <1 ng/mL on Day 0. Then, the cows classified as anestrous (n=51), cyclic-high P4 (n=63), or cyclic-low P4 (n=51) were put into two treatment groups (Ovsynch or Doublesynch) randomly to establish six groups. Cows in the Ovsynch group were administered a GnRH (lecirelin 50 microg, im) on Day 0, PGF (Prostaglandin F2 alpha, D-cloprostenol 0.150 mg, im) on Day 7, and a second dose of GnRH 48 h later. Cows in the Doublesynch group were administered a PGF on Day 0, GnRH on Day 2, a second PGF on Day 9, and a second GnRH on Day 11. Timed artificial insemination (TAI) was performed 16 to 20 h after the second GnRH in both treatment groups. Pregnancy diagnosis was conducted (by ultrasonography) 45+/-5 d after TAI. In anestrous cows and those with high and low progesterone concentration at treatment onset, Doublesynch treatment led to markedly increased pregnancy rates with respect to Ovsynch treatment (P<0.05). On the overall analysis of data, it was revealed that the Doublesynch method increased pregnancy rates by 43 percentage units (29.8% vs. 72.8%, P<0.0001) in relation to Ovsynch. Pregnancy rates of cows having small, medium, or large follicles at the day of second GnRH administration were similar in the Doublesynch group (70.4%, 85.2%, and 63.0%, respectively; P>0.05), wher

Topics: Anestrus; Animals; Cattle; Cloprostenol; Dairying; Dinoprost; Drug Administration Schedule; Estrus Synchronization; Female; Insemination, Artificial; Oligopeptides; Pregnancy; Pregnancy Rate; Progesterone; Time Factors

Twenty-eight pluriparous and non-lactating Santa Inês sheep were synchronized with vaginal sponge and an intramuscular (IM) injection of 37.5 μg of cloprostenol on random days of the estrous cycle (D0); day 6 (D6), at 7:00 am, the devices were removed, and after 24 h (D7), GnRH analog (25 μg of lecirelin) was administrated. Fixed-time artificial insemination (FTAI) with cervical traction by the transcervical route was performed 52 to 58 h after sponge removal. Doppler velocimetry of both uterine arteries was performed on D0, D2, D4, and the morning of D6 (every 48 h), and then every 12 h from D6 to D8 (7:00 a.m. and 7:00 p.m.). We analyzed the peak systolic velocity (PSV), end-diastolic velocity (EVD), time-averaged maximum and mean velocity (TAMAX, TAMEAN), pulsatility index (PI), resistance index (RI), systolic/diastolic ratio (S/D), arterial diameter (AD), and blood flow volume (BFV), with the objective of evaluating the hemodynamic behavior of blood flow velocity parameters of the uterine artery during a short-term progesterone synchronization protocol in ewes. With respect to phases, we noted increases in the means of TAMAX and TAMEAN and decreases of EDV, PI, and RI (P < 0.05). S/D, EDV, TAMEAN, PI, RI, SD, AD, and BFV showed differences between the time of progesterone insertion and the estimated time of ovulation (which was considered the last evaluation) (P < 0.05). The PI and RI values were different when comparing the times of insertion and withdrawal of the progesterone device (PI 2.53-1.54 and RI 0.76-0.68) (P < 0.05). The PI was different with respect to side (P < 0.001), but no side effect was seen in the RI. In conclusion, the two uterine arteries behave differently under the effect of progesterone (intravaginal sponges) and the effect of estradiol during the follicular phase, and estrous phase was responsible for increasing uterine blood flow.

Topics: Animals; Cloprostenol; Estrus Synchronization; Female; Hemodynamics; Insemination, Artificial; Luteolytic Agents; Oligopeptides; Ovulation; Progesterone; Sheep, Domestic; Uterine Artery; Uterus

The ability of gonadotropin-releasing hormone (GnRH) to synchronize ovulation and new follicular wave emergence before a "superovulatory Day 0" protocol was assessed in Santa Inês ewes. For estrus synchronization, a 60-mg medroxyprogesterone acetate sponge was inserted for 6 d. One day before sponge removal, 37.5-μg d-cloprostenol and 300 IU equine chorionic gonadotropin were injected intramuscularly (i.m.). After sponge removal, ewes were assigned to the following 3 groups: (1) GC-1 mL saline at 12 h (n = 10); (2) G24h-0.025-mg lecirelin (GnRH agonist) i.m. at 24 h (n = 10); or (3) G36h-0.025-mg lecirelin i.m. at 36 h (n = 9). Ovarian ultrasonography was conducted to assess follicular dynamics. Blood was collected to determine plasma concentrations of progesterone and estradiol. Females from G36h and GC had a greater (P < 0.05) estrous response than those from the G24h group (78.0 and 90.0 vs 0.0%, respectively). Ewes from G24h and G36h had earlier (P < 0.05) ovulation (48.0 ± 10.2 and 56.7 ± 5.7 h) compared with those from Gc (64.1 ± 9.7 h). The mean number of ovulations per ewe was greater (P < 0.05) in Gc (1.9 ± 0.6) and G36h (2.0 ± 1.0) than G24h (1.2 ± 0.4). Plasma concentrations of progesterone and estradiol differed over time. Follicular growth during the postovulatory day was affected (P < 0.05) by day of the estrus cycle as well as by the interaction (P < 0.05) of treatment and day of the estrus cycle. There was a larger (P < 0.05) population of medium follicles during the first 24 h after the ovulation in G24h compared with Gc, and there was an absence of large follicles in G36h between 36 and 72 h after ovulation. In conclusion, the use of GnRH agonist at 36 h more efficiently synchronized ovulation and promoted the absence of dominant follicles during early diestrus and may be used at the start of superovulatory treatment at 80 h in Santa Inês ewes.

Topics: Animals; Chorionic Gonadotropin; Cloprostenol; Estradiol; Estrus Synchronization; Female; Gonadotropin-Releasing Hormone; Horses; Medroxyprogesterone Acetate; Oligopeptides; Ovarian Follicle; Progesterone; Sheep; Superovulation; Ultrasonography