Effect of different hormonal combinations on follicular wave emergence and superovulatory response in sheep

Souza-Fabjan, J. M. G.; Rosa, R. M.; Balaro, M. F. A.; Pinto, Pedro Henrique Nicolau; Santos, G. B.; Arashiro, E. K. N.; Fonseca, J. F. da; Ungerfeld, Rodolfo; Brandão, Felipe Zandonadi

doi:10.1016/j.theriogenology.2017.07.036

Cited by 13 publications

(8 citation statements)

References 19 publications

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“…The number of collected embryos can be very variable (Bruno‐Galarraga et al, ). The ovulation rate in MOET can be influenced by intrinsic and extrinsic donor factors, that is, superovulation protocol, season, physiological status, age, lactation and nutritional state (Bartlewski et al, ; Gonzalez‐Bulnes et al, ; Lopez Sebastian, Cognie, Cocero, Fuente, & Poulin, ; Souza‐Fabjan et al, ). Although the number of embryos collected from the donor is important, the survival rate of the embryos after implantation in recipients is a critical point for the success of MOET biotechnology.…”

Section: Introductionmentioning

confidence: 99%

Effect of semen and donor factors on multiple ovulation and embryo transfer (MOET) in sheep

Bergstein-Galan¹,

Weiss

Kozicki

2018

Reprod Domestic Animals

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Contents Multiple ovulation and embryo transfer (MOET) is an important tool in the sheep industry for increasing numbers of genetically superior individuals. The objective of this study was to evaluate the effect of semen source (frozen or fresh), the number of embryo collection procedures for each donor (NECP), the season in which embryo transfer and collection was performed, and the age and breed of the donor, on the number of recovered embryos and pregnancy rates after embryo transfer. The Alamos Genetics’ flushing station database was used. This consisted of 140 embryo collection procedures, from 53 Dorper and White Dorper sheep donors, aged between one and eight years, totalling 1,200 collected embryos. Neither the number of retrieved embryos nor the pregnancy rate was affected by the semen preservation method (fresh or frozen), NECP or the age and breed of donor. The season did not affect the number of collected embryos but had a significant effect (p < 0.05) on the recipient pregnancy rate, with higher pregnancy rates reported in the winter (65.57% ± 25.33%) compared with spring (37.11% ± 33.27%), summer (29.95% ± 28.33%) or autumn (35.03% ± 31.66%). There is an estimated increase of 98.4% and 71.5% of embryos recovered in the spring and summer seasons, respectively, when winter is used as reference. The survival of embryos is significantly higher when implanted during the breeding season, more specifically in winter. Embryo collection can be carried out throughout the year in sheep, but there may be a marginal advantage in the use of superovulation and fresh embryo transfer programmes in the autumn and winter.

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Section: Introductionmentioning

confidence: 99%

Effect of semen and donor factors on multiple ovulation and embryo transfer (MOET) in sheep

Bergstein-Galan¹,

Weiss

Kozicki

2018

Reprod Domestic Animals

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“…These authors reported a higher mean of transferable embryos (7.9) in Merino sheep after day 0 treatment when compared to the animals that underwent a traditional (14 days of progestogen) SOV protocol (this last group producing a mean of 5.9 transferable embryos). However, the same methodology could not reach similar embryo outputs in Santa Inês sheep (LIMA et al, 2015;SOUZA-FABJAN et al, 2017;SANTOS et al, 2020).…”

Section: Arashiro Et Almentioning

confidence: 92%

“…Additionally, GnRH administration after estrus synchronization has been shown to improve ovulation synchrony and decreases the incidence of dominant follicles in sheep (REYNA et al, 2007;BALARO et al, 2016). When administering GnRH 36 h after progestogen device removal, the presence of a dominant follicle (> 5 mm in diameter) was reduced but still occurred in 8% of ewes (SOUZA-FABJAN et al, 2017). We hypothesized that the day 0 protocol associated with early GnRH administration would benefit sheep SOV.…”

Section: Arashiro Et Almentioning

confidence: 99%

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

et al. 2022

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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.

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“…The primary factor responsible for the variability in ovarian responses to any superovulation treatment is the ovarian status (the number and size of the antral follicles and CL on the ovaries) at the onset of an exogenous hormonal regimen. Furthermore, synchronization with follicular wave emergence has a major impact on the ovarian response to superovulatory protocols in sheep [ 72 , 73 ]. In sheep, a follicular wave is defined as the emergence or growth of 1–3 follicles from a pool of small follicles (2–3 mm in diameter) on the ovary, reaching >5 mm in diameter before regression (anovulatory wave) or ovulation (ovulatory wave).…”

Section: Factors Affecting Outcomes Of Superovulationmentioning

confidence: 99%

Towards Improving the Outcomes of Multiple Ovulation and Embryo Transfer in Sheep, with Particular Focus on Donor Superovulation

Khan

Jamal

et al. 2022

Veterinary Sciences

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Considerable improvements in sheep multiple ovulation and embryo transfer (MOET)protocols have been made; however, unlike for cattle, MOET is poorly developed in sheep, and thus has not been broadly applicable as a routine procedure. The tightly folded nature of the ewe cervix, the inconsistent ovarian response to various superovulatory treatments, and the requirement of labor to handle animals, particularly during large-scale production, has limited the implementation of successful MOET in sheep. Moreover, several extrinsic factors (e.g., sources, the purity of gonadotrophins and their administration) and intrinsic factors (e.g., breed, age, nutrition, reproductive status) severely limit the practicability of MOET in sheep and other domestic animals. In this review, we summarize the effects of different superovulatory protocols, and their respective ovarian responses, in terms of ovulation rate, and embryo recovery and transfer. Furthermore, various strategies, such as inhibin immunization, conventional superovulation protocols, and melatonin implants for improving the ovarian response, are discussed in detail. Other reproductive techniques and their relative advantages and disadvantages, such as artificial insemination (AI), and donor embryo recovery and transfer to the recipient through different procedures, which must be taken into consideration for achieving satisfactory results during any MOET program in sheep, are also summarized in this article.

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Effect of different hormonal combinations on follicular wave emergence and superovulatory response in sheep

Cited by 13 publications

References 19 publications

Effect of semen and donor factors on multiple ovulation and embryo transfer (MOET) in sheep

Effect of semen and donor factors on multiple ovulation and embryo transfer (MOET) in sheep

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

Towards Improving the Outcomes of Multiple Ovulation and Embryo Transfer in Sheep, with Particular Focus on Donor Superovulation

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