Onset of oestrus and periovulatory events in sheep exposed to 5 and 14 days of CIDR treatment with and without eCG

Uriol, Marta; Martínez-Ros, Paula; Rios, Alejandro; Encinas, T.; González-Bulnes, Antonio

doi:10.1111/rda.13537

Cited by 8 publications

(5 citation statements)

References 8 publications

(9 reference statements)

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“…In this sense, the current study evidenced that all the ewes in both groups (eCG and hCG) displayed a similar number of gonadotrophin-responsive (≥3 mm) and preovulatory-sized (≥5 mm) follicles during the early stages of the follicular phase, induced by CIDR removal. In such a follicular phase, follicular development and periovulatory events in sheep treated with eCG were similar to previous works using the same protocol [ 3 , 11 , 12 ]. In brief, all sheep showed final follicular growth and onset of estrous behavior prior to 48 h, and almost all of them (95.2%, if joining both trials) ovulated around 70 h after CIDR removal and showed corpora lutea of good quality (as evaluated on Day 14 after CIDR removal).…”

Section: Discussionsupporting

confidence: 84%

The Use of hCG for Inducing Ovulation in Sheep Estrus Synchronization Impairs Ovulatory Follicle Growth and Fertility

Cano-Moreno

Lago-Cruz²,

Encinas³

et al. 2021

Animals

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Currently, there is an intense effort to find an alternative hormone to eCG to induce ovulation after estrus synchronization treatments in sheep. One of the proposed alternatives is based on the use of hCG, but the results are controversial since fertility rates are commonly affected. The present study aims to evaluate, therefore, the adequacy of hCG in protocols for the synchronization of estrus and ovulation. Ovarian follicle dynamics, occurrence of estrus behavior and subsequent ovulation, quality of corpora lutea, and pregnancy rate after controlled natural mating were assessed in two consecutive trials. The findings indicate that the low fertility rates reported for the protocols based on the administration of hCG for inducing ovulation during estrus synchronization in sheep may be related to a high occurrence of abnormal follicular growth patterns, disturbances, and retardments of ovulation and concomitant formation of follicular cysts in the treated females. These results preclude their practical application to induce ovulation concomitantly to estrous synchronization treatments.

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Section: Discussionsupporting

confidence: 84%

The Use of hCG for Inducing Ovulation in Sheep Estrus Synchronization Impairs Ovulatory Follicle Growth and Fertility

Cano-Moreno

Lago-Cruz²,

Encinas³

et al. 2021

Animals

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“…Currently, such knowledge is giving way to “follicle-focused” protocols [ 15 ]. These protocols consist of short-term progestative treatments (5–7 days), which are equally as effective as long-term protocols for inducing preovulatory events and ovulation [ 16 , 17 ], with even a higher fertility [ 2 , 18 ]. Short-term protocols aim to synchronize estrus and ovulation but also the follicular wave from which the ovulatory follicles arise.…”

Section: Introductionmentioning

confidence: 99%

Use of GnRH for Synchronization of the Follicular Wave in Assisted Reproductive Technologies in Sheep: A Preliminary Study

Año-Perello

Santos-Jiménez

Encinas³

et al. 2020

Animals

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The present study aimed to set up a short-term protocol for synchronization of follicular wave emergence in sheep, concomitant with estrus synchronization, which would improve ovarian response in assisted reproductive technologies. Administration of a single GnRH dose, concomitant with the insertion of a progesterone-loaded CIDR device, caused regression of gonadotrophin-dependent follicles ≥4 mm in all the GnRH-treated sheep and in around 80% of the controls treated only with CIDR (p < 0.05). Similar percentages of ewes lost all follicles (around 70%) or only the largest one (around 30%) in both groups. Hence, 54.1% and 70% of the sheep lost all large follicles and initiated a new follicular wave in the control and GnRH groups, respectively (p < 0.05). The remaining sheep showed follicles that were still not dependent of luteinizing hormone (LH). So, in fact, all the sheep had non-dominant follicles after treatment. In conclusion, a treatment including GnRH at CIDR insertion would offer a time- and cost-efficient protocol for inducing follicular turnover and synchronizing a new follicular wave at any stage of the estrous cycle.

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“…These results were however, different to that observed by Kridli et al (2009), in brown and black faced Awassi ewes. Nonetheless, it appears that the onset of oestrus following oestrus synchronization occasionally depends on the protocol used (Uriol et al, 2019). However, the Namaqua Afrikaner ewes took longer period showing signs of oestrus.…”

Section: Discussionmentioning

confidence: 97%

A Comparative Study on the Reproductive Performance of South African Indigenous Sheep Breeds Following Oestrus Synchronization

Ngcobo¹,

Nedambale²,

Chokoe³

et al. 2022

American Journal of Animal and Veterinary Sciences

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The aim of the study was to compare the effect of age and live body weight on the oestrus response, duration, pregnancy rate and lambing rate among South African indigenous sheep breeds (Zulu sheep = 36, Bapedi sheep = 26, Damara sheep = 10 and Namaqua Afrikaner sheep = 9). Control Intravaginal Drug Release Dispensers (CIDR's) were inserted into the vagina for 10 days. The twitching of tail and standing to be mounted in the presence of the teaser ram were most targeted signs of oestrus. Data were subjected to an appropriate analysis of variance (ANOVA). The scores were subjected to 1:1 Frequency table and a Chi-Square (²) test for the equal proportions test. One Bapedi ewe loss CIDR before removal date hence was removed from the experimental animals. All Namaqua Afrikaner (100%) ewes responded to the synchronization protocol with the longest oestrus duration (70.7±7.2 h). However, Namaqua Afrikaner sheep scored the lowest rate for conception (44%) and lambing (44%). No significant different (P>0.05) observed for the onset of oestrus among the breeds. Four years old ewes responded better to oestrus synchronization than ≤3, 5 and ≥6 years. Nevertheless, ewes that were ≥6 years old had higher conception rate (94%) and lambing rate (84%). Zulu sheep had higher (89%) lambing rate than Damara (60%) sheep and Namaqua Afrikaner (44%) sheep. Lighter ewes had higher conception (83%) and lambing rate (90%) than heavier (77 and 64%) and moderate (68 and 78%) weights, respectively. In conclusion, Zulu sheep were more fertile than other South African indigenous breeds following oestrus synchronization. On the other hand, young ewes (≤3 years) produced heavier lambs and weaning weight but had higher mortality rate due to inexperience.

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Onset of oestrus and periovulatory events in sheep exposed to 5 and 14 days of CIDR treatment with and without eCG

Cited by 8 publications

References 8 publications

The Use of hCG for Inducing Ovulation in Sheep Estrus Synchronization Impairs Ovulatory Follicle Growth and Fertility

The Use of hCG for Inducing Ovulation in Sheep Estrus Synchronization Impairs Ovulatory Follicle Growth and Fertility

Use of GnRH for Synchronization of the Follicular Wave in Assisted Reproductive Technologies in Sheep: A Preliminary Study

A Comparative Study on the Reproductive Performance of South African Indigenous Sheep Breeds Following Oestrus Synchronization

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