180 Ovarian response to FSH and eCG at super-stimulation treatment for retrieval oocytes by laparoscopic ovum pickup in alpacas

Heavy chain-only antibodies are naturally produced in alpacas, and our laboratory has been interested in developing the use of alpacas as animal models for research associated with different biomedical applications. However, to perform genetic engineering techniques, it is necessary to establish a routine embryo technology in the laboratory. Oocyte retrieval and later development are fundamental steps in obtaining zygotes for genetic engineers to use later. Applying super-ovulation protocols for retrieving healthy cumulus–oocyte complexes is required, especially if slaughterhouse ovaries are unavailable. Follicle-stimulating hormone (FSH) in a multi-shot of decreasing doses and equine chorionic gonadotrophin (eCG) in a one-shot protocol have been used for multiple ovulations and embryo transfer (MOET) procedures, which have resulted in variable responses in alpacas. This study evaluated the effect of FSH and eCG stimulation before laparoscopic ovum pickup (L-OPU) on follicular development and the number of recovered oocytes in alpacas. There were 13 L-OPU sessions (crossover) conducted on adult female alpacas (n = 7), ages 8–12 years, which were examined by transrectal ultrasonography. Animals with ovarian follicles that were more than 6 mm in diameter were treated intramuscularly (i.m.) with GnRH (Cystoreline®), 50 μg (1 mL). Two days later, alpacas received 200 mg of NIH-pFSH-P1 of Folltropin-V® (Vetoquinol) in a decreasing dose, twice daily i.m. schedule over 4 days or a unique dose of 750 IU of eCG (BioVendor). L-OPU was performed 20–24 h after the last FSH injection or 5 days after eCG treatment. Laparoscopic surgery was performed under general anesthesia, starting with anesthesia induction with a combination of ketamine, xylazine, and butorphanol injected i.m. and followed with isoflurane inhalation to maintain anesthesia. L-OPU consisted of three portal systems using 5-mm cannulas with CO₂ insufflation, and aspiration was performed with a 20 G needle attached to a vacuum aspiration pump. The vacuum pressure was adjusted at 50 mm Hg. The collection medium was acquired from IVF Bioscience. All statistical analyses were conducted using PROC GLIMMIX for a mixed model in SAS Studio. There was a statistical difference (P < 0.05) in the number of ovarian follicles, 16.89 ± 1.86 and 9.00 ± 1.94, for the FSH and eCG groups, respectively. The number of ovarian follicles aspirated presented a marginal statistical difference (P = 0.07) of 11.82 ± 2.35 and 8.67 ± 1.73 for FSH and eCG groups, respectively. The number of oocytes retrieved was statistically different (P < 0.05), with 7.09 ± 1.71 for FSH and 3.82 ± 0.94 for eCG, and the recovery rate for FSH and eCG was 61.99 ± 8.20 and 45.03 ± 5.99 (P = 0.07), respectively. In conclusion, FSH treatment was superior to the eCG treatment for super-stimulation of the ovaries of alpacas, which presented an increased proportion of ovarian follicles > 6 mm, allowing the recovery of higher numbers of oocytes that could be used for in vitro embryo technologies. One of the limitations of this report is that our sample size was small. More experiments with larger numbers of animals are needed to draw a more solid conclusion.