Synchronization of cyclic and acyclic embryo recipient mares with donor mares

Abstract

This study compared hormone treatments given to mares during anestrus, spring transition, and different stages of the estrous cycle, by assessing uterine features and pregnancy rates after embryo transfer (ET). Embryo recipient mares (n = 160) were equally arranged as follows: G1-spontaneous ovulation (control), G2-anestrus, G3-spring transition, G4-early estrus, G5-estrus, G6-diestrus, G7-early diestrus treated with a dose of dinoprost, and G8-early diestrus treated with two doses of dinoprost. At treatment initiation (Day-4), G2-7 were given dinoprost and estradiol-17β, thereafter, estradiol-17β was repeated on Days-3,-2, and -1. On Day0, mares received long-acting altrenogest. Then, each mare had one ET performed from Day + 3 to Day + 8 after altrenogest. Immediately before the ET, mares received a boost of altrenogest and had uterine features assessed. Pregnant mares on each of the checks (by 7, 30, 60, and 120d after ET) were maintained on weekly injections of LA-P4 until 120d. G8 received similar management, but dinoprost was repeated on Day-3. G1-G6 and G8 displayed uterine edema and satisfactory pregnancy rates ≥65%. Repeating dinoprost to G8 likely ensured proper luteolysis and response to estrogen as determined by higher uterine edema scores and pregnancy rates than G7 (p < .05). Our results were consistent with previous studies and other successful commercial ET programs (except G7), thus, demonstrating the usefulness of the hormone treatments described herein to synchronize embryo recipient mares with donor mares. Thus, we foresee that other groups may use the strategies described herein for the management of embryo recipient mares.

Use of Intravaginal Progesterone-Releasing Device Results in Similar Pregnancy Rates and Losses to Long-Acting Progesterone to Synchronize Acyclic Embryo Recipient Mares

“…Estradiol was administered for three days to emulate the estrogen being produced by the dominant follicle, and then a dose of LAP4 or insertion of the IPDR meant to emulate an increase in progesterone following ovulation [ 8 ]. Previous studies that used a similar approach with different progestins resulted in satisfactory pregnancy rates, similar to ours [ 6 , 7 , 9 , 10 , 11 , 35 ].…”

“…Transrectal palpation and ultrasonographic evaluations were performed daily from the first day of estrogen administration (D−3) until removal of the second IPRD (Day 18 [D18]). Uterine tone and endometrial edema were scored during each transrectal palpation and ultrasonographic examination respectively, as previously described [ 7 ]. Briefly, no visible endometrial edema was deemed as score 0, and exacerbated endometrial edema characterized by a marked orange-slice appearance with rounded edged endometrial folds was deemed as score 4.…”

“…Synchronization between embryo donor and recipient mares is essential for ET programs [ 4 ]. Satisfactory pregnancy rates can be achieved using recipient mares ovulating from 4 to 9 days before ET [ 5 , 6 , 7 ]. Mares are classified as long-day breeders and seasonal polyestrous, and as many as 80% of mares display a seasonal anestrus from October to March and April to September in the northern and southern hemispheres, respectively [ 8 ].…”

Clinical safety of intratesticular transplantation of allogeneic bone marrow multipotent stromal cells in stallions

“…Oestrous cycles of mares were monitored according to Oliveira Neto et al (), and ovulation induction was then performed with histrelin acetate (250 μg/IM, Strelin ® , Botupharma, Botucatu, SP, Brazil). All mares were artificially inseminated with fresh semen (800 × 10 6 total sperm) at 24 hr after ovulation induction.…”

>b<Efeito da suplementação hormonal com progestágenos em éguas prenhes sobre os hormônios tireoidianos e esteroides dos neonatos>/b<

“…É necessário que o trato reprodutivo tenha exposição prévia aos estrógenos para que haja indução dos receptores de progesterona (NISWENDER et al, 2000). Assim, os tratamentos hormonais permitem sincronizar éguas receptoras com as doadoras de embrião, maximizando o uso das receptoras e diminuindo o número de exames ultrassonográficos (OLIVEIRA et al, 2018).…”