Estrous, ovulation and reproductive responses of ewes synchronized with a long interval prostaglandin–based protocol for timed AI

Burutaran, M.; Fierro, S.; Negrín, F.; Minteguiaga, M.; Gil, J.; Olivera–Muzante, J.

doi:10.1016/j.theriogenology.2023.10.027

Cited by 1 publication

(1 citation statement)

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“…Given that this interval depends on a peak secretion of estradiol, and this peak is also responsible for GnRH/LH surge activation [36,37], it suggests that the ovulatory response to GnRH was induced in a population of follicles already competent for ovulation. However, this follicle population was heterogeneous enough to exhibit less synchronized ovulation in the absence of GnRH, in line with the natural interval estrus-ovulation observed in small ruminants [44,45]. Therefore, GnRH treatment can be used for timed artificial insemination (TAI) year-round, as long as ewes are pre-treated with progesterone during anestrus [46].…”

Section: Discussionmentioning

confidence: 91%

A Subovulatory Dose of Human Chorionic Gonadotropin (hCG) May Sustain Terminal Follicle Development and Reproductive Efficiency during Anestrus in Sheep

Cox,

Carrasco,

Navarrete

et al. 2024

Animals

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The study tested the hypothesis that a single administration of hCG supports the LH-dependent phase of terminal follicular development in synchronized sheep during anestrus, using eCG as a functional reference. Using a clinical approach, four experiments were designed to achieve the following: (1) Identify the inhibitory influence of anestrus on reproduction efficiency; (2) Assess the potential of hCG to keep functional blood concentrations after a single dose; (3) Characterize the effect of different doses of hCG on reproductive functional markers; (4) To compare the ability of hCG to that of eCG to support follicular development and fertility based on the same markers. The results showed that anestrus seems to affect follicular and luteal function under LH dependency as FSH-dependent markers are not compromised; hCG maintains higher blood concentrations than controls for at least 48 h; hCG improves follicular development and ovulatory rates compared to controls and at standards comparable to a breeding season; and ewes treated with hCG exhibit similar performance to those treated with eCG. Our results conclude that hCG can be used to support follicular function during anestrus in sheep, aiming to perfect its regulation in assisted reproduction.

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