Dispersed ovulation at the breeding (BS) and anestrus at non-breeding season (NBS) are major impediments to embryo transfer and insemination programmes. The present study aimed to evaluate a hormonal P4/E2-based synchronisation protocol in mares during both the BS and the NBS on ovarian/follicle behaviour. Mares underwent a hormone protocol to synchronise their ovulation during the BS (n = 8) and NBS (n = 10), starting (D0) with the insertion of an intravaginal device containing 1 g of P4 and 7 mg Estradiol Benzoate IM. (EB). On D9, the device was removed and injected with 0.25 mg of cloprostenol sodic IM and 2 mg of EB IM. Follicular behaviour was evaluated using a daily transrectal ultrasound (24/24 h) from D0 until ovulation. When the dominant follicle (DF) measured at least 35 mm, females were injected with 0.25 mg of gonadorelin acetate IM to induce ovulation. The DF on D0 were similar in animals between BS (18.9 ± 8.4 mm) and NBS (23.7 ± 9.2 mm; p = 0.2700). However, in the BS the DF was smaller (14.2 ± 4.7 mm) on D9 than during NBS (22.0 ± 7.1 mm; p = 0.0177). During the BS, the ovulatory follicle is smaller (p = 0.0042) than during NBS, measured at 33.5 ± 4.6 mm and 41.3 ± 2.8 mm, respectively. Ovulation time after P4 removal was similar during BS (173.1 ± 68.8 h) and NBS (192 ± 58.2 h; p = 0.3507). There was no difference towards an ovulation rate during BS (88%) and NBS (60%; p = 0.0978). There was no difference in spontaneous ovulation during BS (43%) and NBS (0%; p = 0.6085). This hormonal protocol would be an effective tool for inducing cyclicity/ovulation in mares during BS and NBS.

繁殖期（BS）的排卵期和非繁殖期（NBS）的发情期排卵是胚胎移植和授精计划的主要障碍。本研究旨在评估母猪在BS和NBS期间对卵巢/卵泡行为的基于激素P4 / E2的同步方案。母马在BS（n  = 8）和NBS（n = 10），从（D0）开始，插入包含1 g P4和7 mg苯甲酸雌二醇IM的阴道内装置。（EB）。在D9上，将设备移开并注射0.25 mg的氯前列腺素sotic IM和2 mg的EB IM。从D0到排卵，每天经直肠超声（24/24小时）评估卵泡行为。当优势卵泡（DF）测得至少35 mm时，向雌性注射0.25 mg醋酸促性腺激素IM以诱导排卵。动物的D0上的DF在BS（18.9±8.4 mm）和NBS（23.7±9.2 mm; p  = 0.2700）之间相似。但是，在BS中，D9上的DF较小（14.2±4.7 mm），而在NBS上（22.0±7.1 mm；p  = 0.0177）。在BS期间，排卵卵泡较小（p = 0.0042），而不是NBS，分别为33.5±4.6 mm和41.3±2.8 mm。在BS（173.1±68.8 h）和NBS（192±58.2 h; p  = 0.3507）期间，P4去除后的排卵时间相似。BS（88％）和NBS（60％; p  = 0.0978）期间的排卵率没有差异。BS（43％）和NBS（0％; p  = 0.6085）期间的自然排卵没有差异。此激素方案将是在BS和NBS期间诱导母马周期性/排卵的有效工具。