Uterine hemodynamics during a short-term progesterone synchronization protocol in ewes

Area of Science:

• Reproductive Physiology
• Veterinary Medicine
• Animal Science

Background:

• Estrous synchronization protocols are crucial for efficient livestock breeding.
• Understanding uterine artery hemodynamics is key to reproductive success in sheep.
• Short-term progesterone synchronization protocols require detailed hemodynamic evaluation.

Purpose of the Study:

• To evaluate the hemodynamic behavior of uterine artery blood flow during a short-term progesterone synchronization protocol in Santa Inês ewes.
• To analyze Doppler velocimetry parameters of uterine arteries in response to hormonal treatments.
• To assess the impact of progesterone and estradiol on uterine blood flow velocity and volume.

Main Methods:

• Twenty-eight pluriparous, non-lactating Santa Inês sheep underwent estrous synchronization using vaginal sponges and cloprostenol (IM).
• Fixed-time artificial insemination (FTAI) was performed 52-58 hours post-sponge removal, following GnRH analog administration.
• Doppler velocimetry of uterine arteries was conducted at multiple time points, analyzing parameters like PSV, EDV, TAMAX, TAMEAN, PI, RI, S/D, AD, and BFV.

Main Results:

• The study observed significant increases in time-averaged maximum and mean velocity (TAMAX, TAMEAN) and decreases in end-diastolic velocity (EDV), pulsatility index (PI), and resistance index (RI) during specific phases.
• Differences in systolic/diastolic ratio (S/D), EDV, TAMEAN, PI, RI, arterial diameter (AD), and blood flow volume (BFV) were noted between progesterone insertion and estimated ovulation.
• Pulsatility index (PI) and resistance index (RI) values differed significantly between progesterone device insertion and withdrawal, with PI also showing side-specific variations.

Conclusions:

• The two uterine arteries exhibit distinct hemodynamic responses to progesterone (via intravaginal sponges) and estradiol during the follicular phase.
• The estrous phase, influenced by hormonal changes, is associated with increased uterine blood flow.
• Hormonal manipulation in estrous synchronization protocols directly influences uterine artery hemodynamics, with implications for reproductive efficiency.