211 IN VIVO MATURATION AND IN VITRO FERTILIZATION OF ALPACA OOCYTES

Abstract

The objectives of the study were to evaluate the ovarian follicular response, cumulus–oocyte complex (COC) collection rate, fertilization, and culture of COC collected from alpacas after treatment with 2 different gonadotropins. Female alpacas were assigned to Group 1 (n = 8), 200 mg of FSH (Folltropin, Bioniche, Belleville, Ontario, Canada) divided b.i.d. for 3 days, plus a single IM dose of 1000 IU of hCG (Chorulon, Intervet, Salamanca, Spain) 24 h after the last FSH treatment; or Group 2 (n = 10), 750 IU of eCG (Folligon, Intervet) as a single dose, plus a single IM dose of 1000 IU of hCG on Day 3 after eCG treatment (Day 0 = start of the superstimulatory treatment). At 20 to 22 h post-hCG treatment, the ovaries were surgically exposed and COC were aspirated from follicles ≥6 mm and evaluated. The COC with a homogeneous cytoplasm and 2 or more layers of cumulus cells were transferred to plates with a 40-μL drop of TCM-199 maturation medium supplemented with 10% FCS (vol/vol) plus 0.5 μg mL^–1 of FSH, 10 μg mL^–1 of hCG, 0.2 mM sodium pyruvate, 50 μg mL^–1 of gentamicin, and 1 μg mL^–1 of oestradiol under mineral oil with 10 to 12 oocytes/drop and maturated 24 h at 39°C in an atmosphere of 5% CO₂ and high humidity. After maturation, COC were removed and fertilized in vitro using epididymal sperm. Testes were collected from mature males from a slaughterhouse and transported to the laboratory. The caudal epididymide was isolated. A prick was made on the convoluted tubules with a sterile hypodermic needle and the fluid, rich in spermatozoa, was aspirated in syringes containing 2 mL of Tris-fructose egg yolk extender. Motile spermatozoa were obtained by centrifugation at 600 × g on a Percoll discontinuous gradient (45.0:22.5%) for 10 min. The supernatant was then removed by aspiration and the pellet was resuspended in TL-HEPES and centrifuged again at 300 × g for 5 min. The pellet was resuspended in TL-stock. Gametes were co-incubated for 18 h at 39°C with 5% CO₂ and high humidity. Presumptive zygotes were cultured in KSOM medium supplemented with 1 mM glutamine, 0.3 mM sodium pyruvate, 50 μg mL^–1 of gentamicin, EDTA, essential and nonessential amino acids, and BSA for 3 days and cultured in SOF medium for 7 days. Embryo development was evaluated at 72 h and 7 days. Data were subjected to ANOVA. The number of follicles ≥6 mm did not differ at the time of COC collection (19.3 ± 5.7 and 21.5 ± 7.3), and the number of COC collected was 16.7 ± 5.3 and 17.3 ± 6.6 for the FSH group and the eCG group, respectively. The cleavage rate was 45.2 and 42.1% for the FSH group and the eCG group, respectively, at 72 h of culture, and the blastocyst stage at Day 7 (22.2 v. 19.3) did not differ between treatments. In conclusion, the FSH and eCG treatments did not differ in the ovarian follicular response, COC collection rate, fertilization, and culture of COC. Both gonadotropins can be used in the IVF protocol for alpacas.