Collection and in vitro maturation of Mazama gouazoubira (brown brocket deer) oocytes obtained after ovarian stimulation

Abstract

Summary In vitro production of embryos has gained prominence as a tool for use in wildlife conservation programmes in situ and ex situ. However, the development of this technique depends on steps that include ovarian stimulation, collection and oocyte maturation. The purpose of this study was to assess the feasibility of an ovarian stimulation protocol for follicular aspiration, the efficiency of videolaparoscopy for follicular aspiration and test a medium for in vitro oocyte maturation for the species Mazama gouazoubira. Five females were submitted to repeated ovarian stimulation (hormone protocol using controlled internal drug release), and estradiol benzoate on D0 and eight injections of follicle-stimulating hormone, once every 12 h, from D4 onwards at 30-day intervals. Fourteen surgical procedures were performed in superstimulated females, resulting in the collection of 94 oocytes and an average of 17.1 ± 9.1 follicles observed, 13.5 ± 6.6 follicles aspirated and 7.2 ± 3.7 oocytes collected per surgery. After collection, the oocytes were submitted to in vitro maturation for 24 h and stained with Hoechst 33342 dye to evaluate their nuclear status; 64.5% of the oocytes reached MII and 16.1% were spontaneously activated by parthenogenesis. The nuclear status of oocytes that did not undergo in vitro maturation was evaluated; 80.9% were found to be immature.

Embryo production by in vitro fertilization in wild ungulates: progress and perspectives – A Review

“…In this species, it was observed that during the estrous season, the best IVM medium was supplemented with 10 μg/mL FSH, 1 μg/mL LH, 0.2 mM cysteamine, and 50 ng/mL EGF, while in the anestrous season, double these concentrations was more efficient (Yin et al, 2012). Additionally, based on the findings observed in studies with other deer species, Rola et al (2021) observed that the IVM medium containing 5.0 µg/mL FSH, 100 µg/mL hCG and 1.0 µg/mL estradiol was efficient for maturation of brown brocket deer (Mazama gouazoubira) oocytes (64.5%).…”

Assisted Reproductive Technology in Neotropical Deer: A Model Approach to Preserving Genetic Diversity

“…In O. virginianus, the kinetics of the nuclear progression of the oocytes was observed in vitro, and oocytes in the germinal vesicle stage were observed from 0 to 3 h. The maturation of the oocytes of M. gouazoubira collected by LOPU and matured for 24 h resulted in 64.52% of oocytes in MII. In addition, it was found that 14.2% of the oocytes were immature, 4.84% were degenerate, and 16.13% presented spontaneous activation by parthenogenesis [111].…”

“…In this protocol, CIDR ® was used for eight days with an intramuscular application of estradiol benzoate (25 mg) and the administration of eight doses of FSH (total of 130 mg) every 12 h from the fourth day until the seventh day. For M. gouazoubira, ovarian stimulation was considered satisfactory, and the average number of follicles observed after surgery was 17.07 ± 9.12 [111]. In M. americana, females from purebred crosses (buck and hind from the same cytotype) showed good follicular growth response.…”

“…For deer in general, the LOPU technique has enabled an oocyte recovery rate ranging from 46% to 71% [110][111][112]. For M. gouazoubira, the only Neotropical species where LOPU was performed, an oocyte recovery rate of 52.84% was obtained, which resulted in the collection of an average of 7.15 ± 3.72 oocytes/female per surgery.…”