Three superovulation protocols for in vivo embryo production in Santa Inês sheep

Eduardo Kenji Nunes Arashiro,Jeferson Ferreira Da Fonseca,Joanna Maria Gonçalves Souza-Fabjan,Pedro Henrique Nicolau Pinto,Fábio Otero Ascoli,Marc Henry,Julia Timponi Moura Lima,Felipe Zandonadi Brandão

doi:10.1590/0103-8478cr20210308

Eduardo Kenji Nunes Arashiro, Jeferson Ferreira Da Fonseca + Show 6 more

Open Access

https://doi.org/10.1590/0103-8478cr20210308

Copy DOI

Abstract

ABSTRACT: There is still no consensus regarding the best protocol for in vivo embryo production in sheep despite increasing studies in this area. Moreover, there is variability in the response of ewes to superovulation (SOV). An approach to mitigate this inconsistency is to initiate gonadotropin administration under favorable ovarian conditions. The present study compared three treatments in a crossover design: a traditional SOV protocol (TRAD) and “Day 0” D0 SOV protocol with (D0+GnRH), or without Lecilerin (D0-GnRH). Fifteen Santa Inês ewes received 200 mg of FSH at six decreasing doses and PGF2α with the fifth dose of FSH. They were naturally mated with fertile rams and subjected to surgical embryo collection. The number of viable embryos was similar among the different treatments (TRAD = 6.0 ± 4.7; D0-GnRH = 3.8 ± 6.4; D0+GnRH = 7.5 ± 6.5). Regardless of the treatment method, ewes with follicles ≤ 4 mm, at the first FSH dose, produced more viable embryos (9.6 ± 6.0, P < 0.05) compared to ewes that had follicles > 4 mm at the beginning of the SOV (2.9 ± 3.1, viable embryos). Both the TRAD and D0+GnRH groups had fewer animals with large follicles (> 4 mm) at the first FSH dose than the D0-GnRH group (P < 0.05). In conclusion, both the TRAD and D0+GnRH treatments induced a more favorable ovarian condition (follicles ≤ 4 mm) for adequate SOV; although, all three treatments exhibited similar efficacies in Santa Inês sheep.

Highlights

Multiple ovulation and embryo transfer (MOET) programs contribute to the sheep production industry by providing an increased number of descendants from genetically superior donors (COGNIÉ et al, 2003)
In ewes that responded to SOV, the presence of follicles ≤ 4 mm at the beginning of SOV improved the number of viable embryos recovered (Figure 3)
#traditional SOV protocol (TRAD): traditional SOV treatment (14 days of progestogen); #D0-GnRH – SOV starting after an estrus synchronization protocol; # D0+GnRH: similar protocol to D0-GnRH, but with GnRH; CL – corpora lutea

Summary

Introduction

Multiple ovulation and embryo transfer (MOET) programs contribute to the sheep production industry by providing an increased number of descendants from genetically superior donors (COGNIÉ et al, 2003). The ovarian follicular status at the beginning of SOV directly affects the success of the MOET programs. The ovarian response to FSH treatment is related positively to the number of small follicles (2–3 mm), and negatively. Despite the data indicating better embryo output in sheep without a large follicle and with higher antral follicular count (AFC), protocols that do not lead to this specific ovarian condition (10 to 14 days progestogen treatment) at the beginning of SOV can still show satisfactory results and are widely used (GONZÁLEZ-BULNES et al, 2003; BARTLEWSKI et al, 2008; MENCHACA et al, 2009; BERGSTEINGALAN et al, 2019). SOV treatment can be implemented to induce a supraphysiological number of follicles to grow

Methods

Results

Conclusion