flurogestone-acetate and norgestomet

The ultimate aim of any estrus synchronization method is to allow artificial insemination at a predetermined time after the end of treatment. This requires a very tight synchronization of estrus which is not observed in goats after administration of the usual fluorogestone acetate (FGA)/prostaglandin (PG) F2 alpha/equine chorionic gonadotrophin (eCG) treatment. The possibility to improve the synchronization of estrus and luteinizing hormone (LH) peak with different progestagens (FGA versus norgestomet) and routes of administration (vaginal sponge versus subcutaneous ear implant) was evaluated in two experiments where goats received one of three progestagen treatments: (1) a vaginal sponge impregnated with 45 mg of FGA, (2) a half-implant of norgestomet, or (3) a whole implant containing 3 mg of norgestomet. The progestagens were left in place for 11 days and intramuscular injections of 400 or 500 IU of eCG (according to milk yield) and 50 micrograms of an analogue of PGF2 alpha (cloprostenol) were given 48 h prior to progestagen removal. In Experiment 1, 117 cycling goats were checked for the time of onset of estrus, preovulatory LH peak and ovulation rate following estrus synchronization treatment. Goats treated with half-implants came into estrus earlier than those receiving vaginal sponges (27.8 +/- 5.0 h vs. 33.0 +/- 6.6 h, respectively; P < 0.05). No effect of progestagen priming was observed on the variability of the onset of estrus. However, the interval between the time of onset of estrus and LH peak was more variable (P < 0.05) in goats treated with half-implants. In Experiment 2, 170 non-cycling goats were monitored for the time of onset of estrus, percentage of females ovulating, fertility and prolificacy after estrus induction treatment and artificial insemination with frozen-thawed semen performed 24 h after the onset of estrus. No effect of progestagen treatment was observed either on the time or the variability of onset of estrus. The percentage of goats ovulating and overall fertility rate were higher (P < 0.05) in goats receiving vaginal sponges (98.2% and 75.0%, respectively) than those treated with half-implants (81.8% and 45.5%, respectively). However, no significant difference was observed, for the same parameters, in animals receiving implants (86.3% and 58.8%, respectively). In conclusion, estrus synchronization with a norgestomet implant or half-implant did not reduce the variability in the onset of estrus and LH peak. The fertilit

Topics: Animals; Chorionic Gonadotropin; Cloprostenol; Dinoprost; Drug Implants; Estrus Synchronization; Female; Fertility; Flurogestone Acetate; Goats; Horses; Injections, Intramuscular; Luteinizing Hormone; Pessaries; Pregnenediones; Progesterone Congeners; Time Factors

Experiments were conducted to compare the efficacy of synthetic progestogens administered by subcutaneous ear implant or intravaginal sponge to induce a synchronized estrus in adult ewes and ewe lambs and to evaluate reproductive performance (fertility and litter size) to breeding at the synchronized estrus. Experimental animals were representative of three strains maintained in total confinement and exposed to a synthetic light regimen which alternated at intervals of 4 mo from 18 h day length to 10 h day length/24 h. Treatments were applied at different times of the year at the end of a low light cycle. Implants contained Norgestomet (3 mg) impregnated in a polymethacrylate polymer (Implant H) or impregnated in a silastic polymer containing 1.05 (Implant S1), 1.78 (Implant S2) or 2.60 mg (Implant S3) Norgestomet, respectively. Intravaginal sponges contained 40 mg Fluorogestone Acetate. Implants or sponges were left in situ for 12 d and 500 IU pregnant mares' serum gonadotropin was injected im at the time of removal. Following treatment with Implant H, 96% of ewes were judged to be in estrus at 48 h after implant removal. Fertility of adult ewes and ewe lambs (6 to 7 mo of age at time of breeding) at the synchronized estrus were similar after implant H or sponge treatment, but litter size was higher (P less than .05) for adult ewes treated with sponges. The percentages of adult ewes marked by rams within 60 h after removal of silastic implants or intravaginal sponges were similar. There was a tendency for ewe lambs to be marked later than adult ewes and for adult ewes treated with Implant S1 and Implant S2 to be marked earlier than ewes treated with Implant S3 or sponges. Higher percentages (P less than .05) of adult ewes and ewe lambs lambed to breeding at the synchronized estrus after treatment with Implant S2 or Implant S3, respectively, than after treatment with Implants S2 or sponges.

Topics: Animals; Drug Implants; Ear; Estrus Synchronization; Female; Fertility; Flurogestone Acetate; Litter Size; Pessaries; Pregnancy; Pregnenediones; Reproduction; Sheep