Large-scale study of age effects on reproductive parameters and viability of equine oocytes after intracytoplasmatic sperm injection (ICSI) using sexed semen

Author(s)

Reno Roldi de Araujo

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2015-06-16

Examining board members

Luciano Andrade Silva; Rubens Paes de Arruda; Rodrigo Costa Mattos; Flavio Vieira Meirelles; Juliano Coelho da Silveira

• Advisor: Luciano Andrade Silva

Abstract

The aim of the present study was to compare the effect of oocyte donors` age on reproductive parameters, recovery rate and quality of oocytes after ICSI using sexed semen. Polo Ponies (n=79) and Thoroughbred (n=23) oocyte donor mares (400-600kg and 3-29 years) were used during the 2009/2010 and 2011 reproductive seasons in the Southern (San Luis, Argentina) and in the Northern hemispheres (Kentucky, USA), respectively. Mares were divided into three experimental categories: Young Mares (YM: 3-10У), Middle Age Mares (MA: 11-17У) and Old Mares (OM18У). A total of 326 oocytes were recovered in vivo from pre-ovulatory follicles (n=279) and immature-growing follicles (n=47). From those, 224 oocytes were recovered, sorted and directed to a commercial ICSI program with Polo Ponies (first season). During the study`s second season, 57 oocytes were recovered from pre-ovulatory follicles and 47 oocytes from growing follicles and frozen in liquid nitrogen to be used in another study. The evaluated experimental end-points were: Intervals (days) between aspiration or ovulation (AS/OV) to PGF, PGF to GnRH (Day 0=GnRH), AS/OV to Day 0, and AS/OV to Day + 1; uterine edema (UE); cervical tone (CT); maximum diameter of dominant follicle (MdF1) on D0 and D+1, and follicular growth rate. Total number of aspirations, number of follicles aspirated and oocytes recovered per aspiration and/or follicle, the degree of cumulus cell expansion, the presence and quality of polar body (PB), the ooplasm volume, the interval from GnRH to aspiration, GnRH to ICSI, and the cleavage rate (CR) after ICSI were also evaluated. Significant differences between the three experimental categories (YM, MA and OM) were observed for: intervals (days) between PGF-GnRH, AS/OV-GnRH, AS/OV-Day +1, uterine edema on Day 0, CT on Day +1, MdF1 on D0 and D+1 and ooplasm volume. The in vivo recovery rate (RR) was not affected by age (average of 102%, 85% and 73.4% of oocyte recovered per cycle, per F1 and per follicle, respectively; P>0.05). The CR did not differ among experimental categories. In conclusion, an effect of aging could be observed in several reproductive parameters in mares. The oocytes in the present study had a smaller ooplasm volume for OM compared to YM, but this was not effective in predicting oocyte viability or the potential to development through evaluation of the cleavage rate after ICSI using sexed semen (AU)

• FAPESP's process: 10/19955-2 - Evaluation of the effect of oocyte maturation in vivo and in vitro and embryo development after partenogenetic activation; with emphasis on mare age effect.
• Grantee: Reno Roldi de Araújo
• Support Opportunities: Scholarships in Brazil - Doctorate