Reproductive outcome with GnRH inclusion at 24 or 36h following a prostaglandin F2α-based protocol for timed AI in ewes

Olivera-Muzante, J.; Gil, J.; Viñoles, C.; Fierro, S.

doi:10.1016/j.anireprosci.2013.02.013

Cited by 18 publications

(11 citation statements)

References 26 publications

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“…In addition, the G 24h treatment also showed a reduced number of the largest and second largest follicle diameters compared with G c . In practice, these findings may be related to lower fertility and prolificacy rates as suggested previously [14].…”

Section: Datasupporting

confidence: 52%

“…Both the estradiol increase in the bloodstream and the duration of exposure of estrogen receptors to estradiol in the central nervous system may be associated with estrous expression [13]. Olivera-Muzante et al [14] demonstrated that the administration of GnRH 24 h after sponge removal in synchronization protocols for artificial insemination reduced fertility and fecundity. According to these authors, GnRH administration at this time may promote luteal dysfunction and uterine environments that may not be adequate to sustain embryo development.…”

Section: Datamentioning

confidence: 99%

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Potential role for GnRH in the synchronization of follicular emergence before the superovulatory Day 0 protocol

Balaro

Fonseca

Barbosa

et al. 2016

Domestic Animal Endocrinology

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Section: Datasupporting

confidence: 52%

Section: Datamentioning

confidence: 99%

Potential role for GnRH in the synchronization of follicular emergence before the superovulatory Day 0 protocol

Balaro

Fonseca

Barbosa

et al. 2016

Domestic Animal Endocrinology

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“…Finally, one-third of ewes from the WAT group did not show the occurrence of estrus, and half of them did not ovulate. From these results, administration of GnRH earlier than 36 h would not be useful for inducing a better synchronization of ovulation in PGF 2α -based treatments, in agreement with data from Olivera-Muzante and co-workers [25].…”

Section: Discussionsupporting

confidence: 89%

“…Its earlier application indeed induces an early LH surge, which may block the ovarian steroidogenesis and cause anovulation and luteinization of the preovulatory follicle [23]. There are other studies that indicate that even GnRH administration at 24 or 30 h after induction of luteolysis with PGF 2α may compromise reproductive performance [23][24][25]. These results are supported by our current data.…”

Section: Discussionsupporting

confidence: 88%

Use of Propylene-Glycol as a Cosolvent for GnRH in Synchronization of Estrus and Ovulation in Sheep

Santos-Jiménez

Guillen-Gargallo

Encinas³

et al. 2020

Animals

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The foreseen shortage of eCG for estrus synchronization in sheep makes necessary the development of alternative protocols. The aim of the present work was to evaluate the reproductive response of sheep in breeding season to the administration of GnRH using propylene-glycol as a cosolvent and the subcutaneous route for slowing and extending the release of GnRH, as well as the most adequate timing for such administration. In the present study, protocols based on a short-term CIDR treatment and a single subcutaneous dose of GnRH in propylene-glycol at 36 h after CIDR removal induced a similar ovarian response to protocols based on administration of eCG at CIDR removal or intramuscular GnRH in distilled water at 56 h after. In such protocol, 80% of the animals developed estrus in a narrow timing (75% between 36 and 48 h after CIDR removal), and all of them also ovulated in a narrow window (87.5% between 72 and 76 h after CIDR removal, with 62.5% between 72 and 76 h) and showed a similar ovulation rate and plasma progesterone concentrations at the induced estrous cycle. Hence, administration of GnRH in propylene-glycol may constitute an alternative to traditional protocols based on the administration of eCG.

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“…In fact, later studies trying to replace eCG with hCG, at least partly if using PG600, showed poorer fertility yields [7,8]. The most promising results have been found when using GnRH to stimulate ovulation [9], although this hormone has been more frequently associated with prostaglandin-based protocols [10,11,12]. It is important to note that GnRH must be applied at least 24–36 h after progestagen removal or luteolysis [13], since its earlier application (e.g., at progestagen removal) causes luteinization of the preovulatory follicle and anovulation [14].…”

Section: Introductionmentioning

confidence: 99%

Efficiency of CIDR-Based Protocols Including GnRH Instead of eCG for Estrus Synchronization in Sheep

Martínez-Ros

González-Bulnes²

2019

Animals

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The present study examined, for meat sheep (Segureña breed; 2–5-years old, mean body score of 3.5 ± 0.5), the timings of onset of estrus behavior, preovulatory luteinizing hormone (LH) surge and ovulation, and the ovulation rate and fertility obtained after insertion of controlled internal drug release (CIDR) devices for 5 days plus treatment with equine chorionic gonadotrophin (eCG; single dose at CIDR removal, n = 19 ewes) or gonadotrophin-releasing hormone (GnRH, either in a single dose at 56 h after CIDR removal, group CIDR-GnRH, n = 19 ewes; or in one dose at CIDR insertion and another dose 56 h after CIDR removal, group GnRH-CIDR-GnRH, n = 19 ewes). In all the ewes, the appearance of estrus behavior ranged between 84% and 90% and all females showing estrus signs had subsequent preovulatory LH peaks and ovulations. Onset of these events was earlier in the CIDR-eCG group than in the CIDR-GnRH and GnRH-CIDR-GnRH groups (p < 0.05). These differences were mainly determined by the onset of estrus behavior, since timing and intervals of LH peak and ovulation were similar among treatments. In fact, the range of ovulations was narrower in the GnRH-CIDR-GnRH group, which suggests better synchronization of follicular growth (p < 0.05). In conclusion, protocols with two doses of GnRH offer similar yields to eCG protocols.

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Reproductive outcome with GnRH inclusion at 24 or 36h following a prostaglandin F2α-based protocol for timed AI in ewes

Cited by 18 publications

References 26 publications

Potential role for GnRH in the synchronization of follicular emergence before the superovulatory Day 0 protocol

Potential role for GnRH in the synchronization of follicular emergence before the superovulatory Day 0 protocol

Use of Propylene-Glycol as a Cosolvent for GnRH in Synchronization of Estrus and Ovulation in Sheep

Efficiency of CIDR-Based Protocols Including GnRH Instead of eCG for Estrus Synchronization in Sheep

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