Fixed-time deep uterine insemination in PGF2α-synchronized goats.

The aim of this investigation was to optimize fixed-time insemination in goats by clustering ovulations in prostaglandin F(2α)-synchronized goats either with gonadotropin releasing hormone (GnRH) or human chorionic gonadotropin (hCG). The underlying intention was to reduce the incidence of short cycles by providing a more sustained stimulation of the corpus luteum by substituting the commonly used GnRH with longer-acting hCG. It was conjectured that this might render the corpus luteum less prone to premature regression. Sixty pluriparous does were administered 5 mg of the prostaglandin F(2α) preparation dinoprost (Dinolytic; Pharmacia and Upjohn, Erlangen, Germany) during the luteal phase of the estrous cycle. Twenty of these does were administered 0.004 mg of the GnRH analog buserelin (Receptal; Intervet, Unterschleissheim, Germany) 48 hours later; another 20 does received 500 IU hCG (Chorulon; Intervet, Unterschleissheim, Germany) instead. Sixteen hours later the does were inseminated with frozen-thawed semen. The remaining 20 does served as controls and were inseminated 16-18 h after the onset of detected estrus. All 60 treated goats displayed estrous symptoms, the time of onset being similar for all groups (42.6, 37.6, and 40.5 hours after treatment for GnRH-treated, hCG-treated, and control does, respectively). The duration of estrus in the GnRH-treated group was 10 h less than in the other groups (45.1 vs. 56.4 and 54.4 h, P < 0.05). The number of ovulations (assessed by ultrasound monitoring) did not differ among groups (2.4, 2.1, and 2.5, P > 0.05). Monitoring of serum progesterone revealed that the incidence of corpus luteum insufficiency was significantly higher in GnRH- and hCG-treated does than in the control group (40% and 35% vs. 5%, P < 0.05). The pregnancy rate was 50% in the GnRH and 35% in the hCG group as compared with 60% in the controls. Corresponding kidding rates were 40%, 35%, and 60% (P > 0.05). When disregarding does with corpus luteum insufficiency, pregnancy rates would have been 83%, 54%, and 63%, and kidding rates 67%, 54%, and 63%, respectively. The average number of kids born was 1.88, 1.71, and 1.83, respectively (P > 0.05). It may be concluded that fixed time insemination of cycling does treated with prostaglandin F(2α) during the luteal phase, followed by ovulation induction with GnRH or hCG, would be an effective management tool if it were possible to control the high incidence of corpus luteum insufficiency. The attempt to achieve this by substituting GnRH with hCG, was not met with success. Until a solution for the problem has been found, it is advisable to inseminate prostaglandin-synchronized does 16-18 hours after the onset of detected estrus.

Ovsynch synchronization and fixed-time insemination in goats.

This study assessed the efficacy of an Ovsynch protocol (vs. the classical cronolone containing vaginal sponge+eCG treatment) to generate fixed-time insemination in goats during the breeding season. Each regimen was applied to 24 Boer goat does. Onset and duration of estrus were determined with an aproned male and follicular development was monitored by ultrasonography. Ovulation and quality of the corpora lutea were established from progesterone concentrations. In 10-11 goats per group, LH concentrations were determined throughout the preovulatory period. Does were inseminated at pre-determined times (16 h after the second GnRH injection and 43 h after sponge removal). Estrus was identified in 96% of the Ovsynch-treated goats (at 49 h after prostaglandin injection) and in 100% of the goats synchronized with sponges (at 37 h after sponge removal). Low progesterone concentrations at the time of AI were observed in 21/24 and 24/24 goats synchronized by Ovsynch and sponges, respectively. Synchronization of the LH surge was tighter following Ovsynch compared to sponge treatment. Kidding rates (at 58 and 46% in the Ovsynch and sponge groups, respectively) and prolificacy (at 1.86 and 1.83 in the Ovsynch- and sponge-treated goats) were similar for both groups, as were the number of ovulations (2.9 and 3.3) and the proportion of does with premature corpus luteum regression (29 and 17%). When excluding does with premature luteal regression and those with low progesterone levels when receiving prostaglandins, kidding rate reached 87.5% (14/16) after Ovsynch. During the breeding season, the Ovsynch protocol may thus be an useful alternative to the sponge-eCG treatment.

Technical Note: Transcervical deep cornual insemination of goats.

A newly developed technique for trans-cervical deep uterine insemination of goats is described. An experiment was conducted to compare this transcervical method with the laparoscopic intrauterine insemination using frozen-thawed semen. Of the 46 primiparous and 21 multiparous estrus-synchronized Boer goat does inseminated transcervically, 71% (22/31) kidded compared with 53% (19/36) of does inseminated laparoscopically (P < 0.025). The corresponding litter sizes were 2.27 and 1.89 (P < 0.01). In another 34 parous does inseminated transcervically without preceding hormone treatment, kidding rate and litter size were 71% and 1.76, respectively. We conclude that transcervically conducted bilateral deep cornual insemination may be considered a viable alternative to laparoscopic insemination.

Nonsurgical embryo collection in goats treated with prostaglandin F2alpha and oxytocin.

Embryos were collected transcervically from 38 unanesthetized goats in a standing position. Goats of the Boer breed were superovulated by injecting them with 16 mg of pFSH containing 40% LH. Collection took place 6 d after the last mating. A luteolytic dose of PGF2alpha was injected 16, 8, or 0 h before flushing the uterine lumen. One half of each group received an additional injection of oxytocin just before flushing. The flushing catheter was introduced transcervically, and 24 flushings were performed, with a 2-h pause between the first 12 and the last 12 flushings. Injection of PGF2alpha 16 or 8 h before transcervical embryo collection resulted in a significant increase (P < .001, chi-square test) in embryo recovery (-16 h: 91% with oxytocin, 85% without; -8 h: 91% with oxytocin, 80% without) compared with an injection at the time of collection (52% with oxytocin, 66% without). The recovery rate which was estimated as the percentage of embryos recovered relative to the number of corpora lutea counted endoscopically, was comparable to that achieved by surgical collection. There were no differences among groups with regard to embryo morphology. Embryos were transferred, and healthy kids were born. The nonsurgical collection of caprine embryos may be considered a viable alternative to conventional surgical procedures.