Embryo transfer in horses is a reproductive technology that involves collecting a fertilized embryo from a donor mare and implanting it into a recipient mare, which then carries the pregnancy to term. This technique allows for the production of multiple offspring from a single mare within a breeding season. The procedure includes several stages: synchronization of the donor and recipient mares' estrous cycles, collection of the embryo, and its subsequent transfer to the recipient mare. Embryo transfer is utilized to enhance genetic dissemination, preserve valuable genetics, and manage breeding schedules. This page aggregates peer-reviewed research studies and scholarly articles that explore the methods, efficiency, and applications of embryo transfer in equine reproduction.
Pool-Anderson K, Raub RH, Warren JA.Six pairs of full-sibling Quarter Horse foals were produced by non-surgical embryo transfer and immediate rebreeding of donor mares. Each pair of donor/recipient mares consisted of one multiparous (donor) and one nulliparous (recipient) mare of similar body type and size. Milk yield was determined within 2 d of 8, 15, 22, 29 d (early lactation); 45, 60 d (midlactation); and 90, 120 d (late lactation) postpartum by the weigh-suckle-weigh method. On the following day, milk samples were collected, and foals were weighed and measured for wither height, heart girth, metacarpal length, metatarsal le...
Oriol JG.In most domestic animals, the zona pellucida is the outermost extracellular layer that covers the blastocyst before implantation. However, in the horse, an acellular membrane, the capsule, replaces the zona pellucida and envelops the developing conceptus during the 2nd and 3rd weeks of gestation. Although this structure was first described by Bonnet in 1889, it received little attention until the 1970s when its rediscovery by Marrable and Flood (1975) led to a series of reports (see review by Betteridge 1989). Nevertheless, until recently the structure, origin, and function of the capsule have...
Hochi S, Fujimoto T, Braun J, Oguri N.The objective of this study was to investigate the in vitro and in vivo developmental abilities of equine embryos cryopreserved by vitrification. Twenty-eight embryos were recovered from Native pony and Thoroughbred mares at Days 5 to 7 by nonsurgical uterine flushing (detection of ovulation=Day 0). The vitrification solution contained 40% ethylene glycol, 18% Ficoll, and 0.3 M sucrose in PBS. The embryos were placed for 1 to 2 min in vitrification solution (Group 1) or following exposure to 20% ethylene glycol in PBS for 10 to 20 min (Groups 2 and 3). Single embryos were loaded in 0.25-ml str...
Dippert KD, Jasko DJ, Seidel GE, Squires EL.Embryo recovery per ovulation has been shown to be lower in superovulated mares than in untreated controls. The objectives of this study were to 1) determine whether follicles stimulated with superovulatory treatment ovulate or luteinize without ovulation, 2) determine fertilization rates of oocytes in oviducts of superovulated and control mares, and 3) evaluate viability of early stage embryos from superovulated and control mares when cultured in equine oviductal cell-conditioned medium. Cyclic mares were randomly assigned to 1 of 2 groups (n=14 per group) on the day of ovulation (Day 0): Gro...
Weber JA, Woods GL, Freeman DA, Vanderwall DK.The objective of this experiment was to contrast the influence of the oviductal and uterine environments on development of Day-2 embryos. Embryos were transferred to oviducts or uteri of synchronous recipient mares, or were incubated in oviductal co-culture, in uterine co-culture or in defined culture medium. Significantly more (P < 0.02) embryos transferred to the oviduct versus the uterus survived until Day 11 after ovulation (5 7 vs 0 7 , respectively). Significantly more (P 0.1) in oviductal co-culture versus uterine co-culture (3 7 vs 6 7 , respectively), or in oviductal co-culture ve...
Wegner W.In 1893 a major component of veterinary practice derived from 4 million horses and from farm animals, whereas thousands of dogs were even slaughtered every year, especially in Saxony and Silesia. Nowadays companion animals figure as an element of ever growing importance for the practitioner. Teaching and research adapted themselves to this altered situation, research funding and professional politics not yet so completely. In former days veterinarians even presided the licensing committees for breeder animals--today the animal breeding act merely mentions them in connection with institutions o...
Philpott M.This review summarizes the major infectious diseases of the three major agricultural species (cattle, sheep and pigs) and horses, and presents the evidence for and against the possibility of infectious agents being transmitted between animals via the venereal route or by the use of semen or early embryos in commercial artificial insemination (AI) or embryo transfer (ET). Cattle feature most prominently in the widespread distribution of frozen semen, and national and international organizations have set out guidelines to work towards disease-free bull studs with semen free from potential pathog...
Kudlac E, Grygar J.The frequency of double ovulation and the chances of twin pregnancy in the mare are presented with reference to the relevant literature. A novel manual technique for reducing the embryo number from two to one is introduced and illustrated by ultrasonographic images.
Freeman DA, Woods GL, Vanderwall DK, Weber JA.The hypothesis that equine embryos initiate oviductal transport in mares was tested by placing day 6 uterine embryos in the oviducts of day 2 (n = 10) or day 5 (n = 10) recipient mares and attempting to collect the embryos from the uterus 48 h later. To determine whether the surgical transfer procedure initiated oviductal transport, medium alone was placed in the oviducts of day 2 (n = 10) inseminated mares (sham transfer), and uterine embryo collections were attempted 48 h later. Embryos were transported through the oviduct of day 2 recipients by day 4 (instead of day 5 to 6) in six of ten ma...
Ball BA, Miller PG.In this study we examined the ability of equine oviductal epithelial cells (OEC) to support the development of four- to eight-cell equine embryos in vitro and investigated the ability of co-cultured embryos to continue normal development after transfer to synchronous recipient mares. Equine embryos obtained at Day 2 after ovulation were cultured with or without OEC for 5 days. Those OEC co-cultured embryos that reached the blastocyst stage and embryos recovered from the uterus at Day 7 were surgically transferred to synchronous recipient mares. Co-culture with OEC improved (P < 0.01) develo...
Freeman DA, Weber JA, Geary RT, Woods GL.The objectives of this study were 1) to determine the time of embryo transport through the mare oviduct, 2) to determine whether equine embryos increase in diameter prior to the time of oviductal transport, and 3) to assess the stage of equine embryonic development at the time of oviductal transport. The time of oviductal transport (interval from ovulation to uterine entry) was estimated by collecting embryos from the mare oviduct or uterus at 2-hour intervals from 120 to 168 h postovulation. The time of oviductal transport was 130 to 142 h, since 9 9 embryos were located in the oviduct from 1...
Kot K, Tischner M.The aim of the experiment was to determine the effect of a year-to-year prolonged daylength on the patterns of equine reproductive activity and results of embryo recovery. Experiments using Konik Polski mares were conducted over four reproduction seasons. Five mares were exposed to a regimen of artificially prolonged daylength (APD) and another five mares in a control group were kept under conditions of natural daylight. Both the control and experimental groups were examined for appearance of estrus, ovulation and also for the state of their coats. A single stallion was used for breeding all o...
Heap RB, Hamon MH, Allen WR.Aromatase distribution in membranes of preimplantation horse and donkey conceptuses was compared by measuring the incorporation of [3H]androstenedione into oestrone and oestradiol-17 beta. In the donkey conceptus, aromatase activity was similar in all the tissues examined (yolk sac, chorionic girdle and allantochorion), whereas in the horse it was generally lower and showed the relationship chorionic girdle greater than yolk sac greater than allantochorion. A higher proportion of labelled precursor was incorporated into oestradiol-17 beta by extra-embryonic tissues of the donkey compared with ...
Carney NJ, Squires EL, Cook VM, Seidel GE, Jasko DJ.Donor mares of mixed, light-horse breeds, maintained at Colorado State University, provided 104 embryos for immediate transfer (fresh embryos). One hundred and thirty-six additional embryos were collected on various breeding farms in the United States and were shipped to Colorado State University via commercial airlines (cooled embryos). Embryos were harvested 7 d after ovulation, graded, and either transferred into a mare immediately (<1 h) or placed in Ham's F-10 medium plus 10% fetal calf serum in an atmosphere of 5% CO2, 5% O2, 90% N2 and packaged in a passive cooling unit (Equitai...
Hinrichs K, DiGiorgio LM.A technique was developed in which immature horse oocytes, obtained from slaughterhouse specimens, were transferred to the pre-ovulatory follicle of a mare in vivo, with resulting oocyte maturation, ovulation, fertilization and embryo development. Oocytes were collected from all follicles greater than 3 mm, and were classified as immature, maturing, expanded or denuded. The transfers were performed in the standing, tranquilized mare. The ovary containing the pre-ovulatory follicle was grasped per rectum. A trochar and cannula were placed through the abdominal wall in the flank area, ipsilatera...
Hinrichs K, Schmidt AL, Memon MA, Selgrath JP, Ebert KM.Embryos were recovered from the uteri of mares 5 d after ovulation. Six embryos, all morulae, were placed singly in 200-ul droplets of Ham's F-12 with 10% fetal calf serum and cultured at 37 degrees C in a 5% CO(2) atmosphere. The embryos expanded to form blastocysts by the third day of culture. The blastocysts hatched from their zona pellucida, rather than the zona thinning and flaking off, as occurs in vivo. Hatching from the zona pellucida began on the third day of culture and was complete in five of six embryos by the sixth day. The embryonic capsule, normally present in equine embryos aft...
Sertich PL.Pregnancy was established by transcervical transfer of embryos from performance mares into recipient mares. Estrus was synchronized between donor (n = 17) and recipient (n = 43) mares. After a greater than or equal to 25-mm follicle was detected, donor mares were bred artificially daily until ovulation. Day of ovulation was recorded. Uterine flushes (n = 111) were performed on donor mares 7 days after ovulation, and recovered embryos were transferred transcervically to recipient mares within 2 hours. Embryos were recovered from 40.5% of uterine flushes. Of transferred single embryos, 65.7% res...
Hinrichs K, Riera FL, Klunder LR.Embryo transfer was performed in three mares with gonadal dysgenesis. Karyotypes of the mares were as follows: Mare 1, 63,XX, 64,XX, 65,XX; Mare 2, 63,X; and Mare 3, 65,XXX. The mares were administered progesterone in oil, 300 mg intramuscularly daily, starting 1 or 2 days after donor mare ovulation. Embryos were transferred on day 7 after donor ovulation. Mare 1 became pregnant after the first embryo transfer and had a normally developing fetus on necropsy on day 45 of gestation. Mare 3 became pregnant after the third embryo transfer, but the embryo was lost between day 14 and day 18 of gesta...
Ginther OJ.Recent findings on the origin and development of twins from ovulation (Day 0) to fixation (mean: Day 16) are reviewed. Available data show that almost all twins originate from multiple ovulations. Results of recent ultrasound studies indicate that the number of days between double ovulations does not affect the conception rate per ovum or embryo survival during the first 16 days after each ovulation. Embryo reduction is the natural elimination of excess embryos so that only one embryo enters the foetal stage. In two studies, embryo reduction before or on the day of fixation was not considered ...
Pace-Owens S.Gamete intrafallopian transfer (GIFT), developed in 1984, was the result of further studies on in vitro fertilization (IVF). Since that time many nurses have worked in settings near in vitro fertilization centers and, therefore, have a basic understanding of the technology. An overview is given of the GIFT procedure to prepare nurses to advise and refer couples who may qualify for GIFT and to highlight the shift in the fertility program nurse coordinator's functions toward the positions of administrator and consultant.
Katila T, Oijala M, Kotilainen T, Väisänen K.Four subfertile mares (at least 2 barren years) were used as donors in an embryo transfer program. The embryo recovery rate was 50%, varying between 0-100. The transfer of 9 embryos resulted in the pregnancy rate of 44%. The efficiency of embryo transfer using subfertile mares is low. In this material 20% of flushings resulted in a pregnancy. Fyra subfertila ston (gatt galla i minst 2 är) användes som donatorer i ett program för embryot rans fer. Femtio procent av embryon tillvaratogs (varians 0–100%). Transfer av 9 embryon gav en dräktighetsresultat på 44%. Embryotransfer från subfert...
Ball BA, Little TV, Weber JA, Woods GL.The estimated embryonic loss rate between Days 4 and 14 after ovulation for young, normal mares (9%) was significantly lower (P less than 0.01) than the estimated embryonic loss rate for aged subfertile mares (62%). Fertilization rates, which were based on the recovery of embryos at Day 4 after ovulation, were 96% and 81% (P less than 0.1) for normal and subfertile mares, respectively. Day-4 embryos were collected from the oviducts of normal and subfertile donors mares. These embryos were transferred to the uteri of synchronized, normal recipient mares to test the hypothesis that the high inci...
Sirois J, Betteridge KJ.To recover intact Day-10.5 to Day-16.5 equine conceptuses (Day 0 = ovulation), a rigid catheter was used for 131 collections from donor mares diagnosed pregnant by ultrasonography. A total of 139 conceptuses were recovered, comprising 124 singletons, six pairs of twins and one set of triplets. Of these, 120 (86%) were intact after the collection, 14 (10%) had collapsed, and in five cases (4%), collapsed trophoblastic membranes were surrounded by an intact capsule. The recovery rate of intact conceptuses ranged from 99% on Days 10.5 to 12.5 to 40% on Day 16.5. More uterine flushes per recovery ...
Hinrichs K, Sertich PL, Solorzano NM, Caldwell LA.An immediate, qualitative enzyme-linked immunosorbent assay (ELISA) for progesterone was evaluated for use in determining the day of ovulation in an equine embryo transfer program. Plasma samples were collected from 27 mares from the third day of estrus to the second day of diestrus for 50 cycles. Ovulation was detected by ultrasound examination per rectum. Plasma progesterone concentrations were estimated using the qualitative assay to detect the time of the rise in progesterone after ovulation. Qualitative scores were compared to progesterone concentrations for the same samples as measured b...
Moussa M, Duchamp G, Mahla R, Bruyas JF, Daels PF.Equine embryos have been successfully transferred after 24h cooled storage in Ham's F-10. The aim of this study was to compare the viability of equine embryos in vitro and in vivo after 6 and 24h cooled storage using three media and to examine the relationship between embryo size and viability after 24h cooled storage. In Experiment 1, the viability of embryos was evaluated using DAPI-staining after 0, 6 or 24h in Ham's F-10, 24h in Emcare embryo holding solution (EHS) or 24h in ViGro holding plus (VHP) (n=10/group). The mean number of dead cells was similar for embryos stored in Ham's F-10, E...
Poitras P, Guay P, Vaillancourt D, Zidane N, Bigras-Poulin M.The main objective of this study was to evaluate two freezing protocols and the effect of agar embedding on survival of day 6.5 equine embryos. A total of 133 embryos were used, in one group (n = 51), embryos were first embedded in agar before the freezing protocol was started. A freezing protocol to -30 degrees C or -33 degrees C was used before plunging embryos into liquid nitrogen (LN2). The embryos were thawed in water at 37 degrees C, evaluated and placed in culture. After 24 h culture, the embryos were evaluated for their morphology and development. No differences were observed between e...
Braun J.Although foals born after embryo transfer are eligible for registration in the majority of horse breeds, application of embryo transfer is still rare. This is mainly due to the lack of a possibility for superovulation. Uterine stage embryos can be recovered by a non-surgical flushing technique. Transfer can be accomplished by non-surgical as well as surgical methods. In contrast to the situation in cattle, most related technologies are scarcely available. Methods of cryopreservation as well as bisection of embryos are hampered by the fact that suitable embryos (morula) can be collected from th...
Peyrot LM, Little TV, Lowe JE, Weber JA, Woods GL.Embryo autotransfer is defined as the collection of an embryo from and the transfer of this embryo into the same animal. The objectives of this study were to: 1) test the hypothesis that oviduct transport of the equine embryo from the oviduct into the uterus is not dependent on a unilateral embryo-corpus luteum interaction, 2) develop an embryo autotransfer technique for the mare and 3) compare the success rates of Day 4 embryos surgically autotransferred from the oviduct ipsilateral to ovulation to either the oviduct (n=10 mares) or the uterine horn (n=10 mares) contralateral to ovulation. Se...
Logan NL, McCue PM, Alonso MA, Squires EL.Superovulation could potentially increase embryo recovery for immediate transfer or cryopreservation. The objectives were to evaluate the effect of pretreatment with progesterone and estradiol (P+E) on follicular response to eFSH and compare doses of eFSH and ovulatory agents on follicular development and ovulation in mares. In Experiment 1, 40 mares were assigned to one of four treatment groups. Group 1 consisted of untreated controls. Group 2 mares were administered eFSH without pretreatment with P+E. Group 3 mares were administered P+E for 10 days starting in mid-diestrus followed by eFSH t...
Hinrichs K, Sertich PL, Solorzano NM, Caldwell LA.An immediate, qualitative enzyme-linked immunosorbent assay (ELISA) for progesterone was evaluated for use in determining the day of ovulation in an equine embryo transfer program. Plasma samples were collected from 27 mares from the third day of estrus to the second day of diestrus for 50 cycles. Ovulation was detected by ultrasound examination per rectum. Plasma progesterone concentrations were estimated using the qualitative assay to detect the time of the rise in progesterone after ovulation. Qualitative scores were compared to progesterone concentrations for the same samples as measured b...
Taveiros AW, Oliveira MA, Lima PF, Tenório Filho F, Bartolomeu CC, Santos MH, Oliveira LR, Iunes-Souza TC, Freitas JC.Ten pluriparous mares were used as donors to supply embryos which were transferred into 103 recipients, 31 of which were nulliparous, 34 were pluriparous and lactating, and 38 were pluriparous and non-lactating. The embryos were recovered eight days after ovulation and pregnancy was confirmed by ultrasound six days after the transfer; the length of the embryos was measured ultrasonographically on days 12, 14, 16, 18, 20, 25 and 30 after the embryo transfer. One hundred and fifteen of 200 flushes provided embryos, 12 being degenerate and 103 being viable embryos. From the 103 embryo transfers c...
Coutinho da Silva MA, Carnevale EM, Maclellan LJ, Seidel GE, Squires EL.The objective of the study was to compare embryo development rates after transfer of oocytes collected 22 or 33 h after hCG injection into recipients inseminated within the uterus or the oviduct. Oocytes were collected at approximately 22 or 33 h after hCG injections and incubated for approximately 16 or 1.5 h, respectively, before transfer. Intrauterine inseminations using 1 x 10(9) progressively motile sperm were done approximately 12 h before and 2 h after transfer. For intraoviductal inseminations (gamete intrafallopian transfer [GIFT]), semen was centrifuged through a Percoll gradient, an...
Pinna A, Martins G, Souza G, Lilenbaum W.The aim of this study was to demonstrate that seroreactivity against Leptospira is significantly associated to the reproductive efficiency of recipient mares of an embryo transfer (ET) programme. A serosurvey was conducted from August 2007 to March 2009 in five herds from Rio de Janeiro, Brazil, with high rates of reproductive failure, as early embryonic death (>12%), abortion (>12%) and perinatal death. Detailed information about the losses was obtained from practitioner. A total of 338 recipient mares were tested by microscopic agglutination test, and 226 (66.9%) were seroreactive, mainly ag...
Hinrichs K.A research study is a product of not only a question and its pursuit but also the people, places, and facilities available at the time. My work in equine assisted reproduction has progressed from embryo transfer to oocyte maturation, oocyte transfer, intracytoplasmic sperm injection, embryo biopsy, embryo vitrification, and cloning, as a result of collaborations with an array of remarkable people. This is a summary of some of the stories behind the studies.
Hannan MA, Haneda S, Murata K, Takeuchi S, Cheong SH, Nambo Y.Until now, there have been no reports of foals born through embryo transfer after artificial insemination using frozen semen in Japan. The aims of this study were to develop a riding crossbred horse and evaluate the prospects of embryo transfer technology in multiplying horse population. In both donor and recipient mares, luteolysis was induced by the administration of 0.1 mg Cloprostenol to synchronize the onset of estrus, and ovulation was induced by administering 2000 IU human chorionic gonadotropin (hCG) or 0.75 mg Deslorelin. Frozen semen from an Irish Connemara pony stallion was used to ...
Meier HP, Gertsch U, Kohler S.Twin pregnancies are a serious problem in stud medicine as they terminate in most cases in abortion, stillbirth or the delivery of dead or weak and deformed foals. In recent years, the introduction of sonography has greatly improved the management of mares with twin conceptuses, in particular monitoring the phenomenon of spontaneous embryo reduction to a single vesicle. This allows supervision of pregnancy with relatively little expenditure and loss of time. We document the spontaneous reduction to single vesicles of unilateral twin pregnancies in a draught- and a warmblood-mare. In both mares...
Rua MAS, Quirino CR, Rodrigues ACC, Christo MM, Barreto MAP.The objective of this study was to evaluate the environmental effects on embryo recovery rate and pregnancy rate of Mangalarga Marchador mares. The reproductive characteristics of donor and recipient mares were evaluated during five years in Brazilian tropical environment. The mares were used throughout the year and seasons were classified as: October to April (breeding season - BS); May (autumn transition out of the breeding season - ATBS); June to August (non-breeding season - nBS); and September (vernal transition into the breeding season - VTBS). Daily temperature rainfall and hours of day...
Wilsher S, Allen WR.Eight day 10 horse embryos were transferred non-surgically to recipient mares that had ovulated 7 days after the donors. The embryonic vesicle was seen ultrasonographically in all eight recipients, and three out of eight (38%) of the vesicles developed an embryo proper with a beating heart. Conceptus expansion was initially slower than that in control mares but continued until day 22 (recipient day 15). Time of fixation of the vesicle was related to its diameter, rather than uterine stage. Although the embryo proper first appeared ultrasonographically on day 22, as normal, it grew more slowly ...
Alonso MA, Silva LA, Affonso FJ, Lemes KM, Celeghini ECC, Lançoni R, Carvalho HF, de Arruda RP.Establishment of pregnancy after embryo transfer is the ultimate goal of an embryo transfer program and increasing pregnancy rates and reducing pregnancy loss are mandatory. The utilization of treatments to improve conception rates in recipient mares has been the focus of several research groups over the last years and the results are controversial. Some studies using human chorionic gonadotrophin (hCG) found promising results. Our hypothesis was that hCG administration would cause an additional stimulation on luteal function, uterine and luteal vascularization and progesterone concentration, ...
Choi YH, Love LB, Varner DD, Hinrichs K.Holding immature oocytes before the onset of maturation simplifies oocyte transport and aids in scheduling later manipulations. We report here a method for holding equine oocytes in the absence of meiotic inhibitors. In Experiment 1, immature oocytes with expanded cumuli were cultured at 38.2 degrees C in medium containing cycloheximide, or were held at room-temperature in M199 with Hanks' salts, for 16-18 h before maturation. Control oocytes were matured immediately after recovery. Oocytes were fertilized by intracytoplasmic sperm injection and cultured for 4d. Embryo development was not diff...
Scherzer J, Davis C, Hurley DJ.The major difficulty in providing the benefits of embryo cryopreservation for equine agriculture is the mismatch between the optimal embryo age for collection from the mare (7-8 days after ovulation was detected) and the optimal age for freezing under current methods (6.5 days after ovulation). To overcome this limitation, we tested a method to enhance penetration of cryopreservative across the capsule and trophoblast of day 7 and 8 embryos combined with rapid freezing by vitrification. Six small embryos (<300 μm in diameter) were collected on day 6-7 after ovulation and twelve larger embryos...
Schmid RL, Kato H, Herickhoff LA, Schenk JL, McCue PM, Chung YG, Squires EL.In Expt 1, compact cumulus oocyte complexes (COCs) were matured in: (i) control medium (Hepes-buffered TCM-199 with 10% oestrous cow serum (OCS) + oestradiol, LH and FSH); (ii) Hepes-buffered TCM-199 with 20% follicular fluid; or (iii) control medium containing 250 ng progesterone ml(-1). Mature oocytes were collected by transvaginal aspiration as a positive control for the in vitro maturation (IVM) treatments. Oocytes were fertilized by ICSI and cultured in Menezo's B2 + 5% fetal calf serum (FCS). There were no significant differences among IVM treatments. In Expt 2, oocytes with expanded COC...
Meuffels-Barkas J, Wilsher S, Allen WRT, Ververs C, Lueders I.Recent loss of rhinoceros subspecies has renewed interest in using more advanced assisted reproductive technologies (ART) in rhinoceroses and elephants. Currently, only semen collection, semen preservation and artificial insemination (AI) have been used repeatedly with success in these species. Although ovum pick-up (OPU) and intra-cytoplasmic sperm injection (ICSI) have been reported in rhinoceroses, the techniques are not yet optimised. In contrast, multiple ART applications are routinely used in the horse. Since elephant and rhinoceroses share some reproductive features with equids, we post...
Klein C, Troedsson MH.Maternal recognition of pregnancy in the horse is the sum of events leading to maintenance of pregnancy; in a narrow sense, maternal recognition of pregnancy refers to the physiological process by which the lifespan of the corpus luteum is prolonged. The horse is one of the few domestic species in which the conceptus-derived pregnancy recognition signal has not been identified. The presence of the conceptus reduces pulsatile prostaglandin F(2α) secretion by the endometrium during early gestation in the mare, partly attributed to the reduced expression of cyclooxygenase-2. Cyclooxygenase-2 has...
Robles M, Peugnet PM, Valentino SA, Dubois C, Dahirel M, Aubrière MC, Reigner F, Serteyn D, Wimel L, Couturier-Tarrade A, Chavatte-Palmer P.Following embryo transfer (ET), the size and breed of the recipient mare can affect fetal development and subsequent post natal growth rate and insulin sensitivity in foals. Objective: To investigate placental adaptation in pregnancies where increased or restricted fetal growth was induced through ET between Pony, Saddlebred and Draught horses. Methods: In vivo experiment. Methods: Control Pony (P, n = 21) and Saddlebred (S, n = 28) pregnancies were obtained by artificial insemination. Increased pregnancies were obtained by transferring Pony (P-D, n = 6) and Saddlebred (S-D, n = 8) emb...
Garner DL, Evans KM, Seidel GE.The sex of mammalian offspring can be predetermined by flow sorting relatively pure living populations of X- and Y-chromosome-bearing sperm. This method is based on precise staining of the DNA of sperm with the nucleic acid-specific fluorophore, Hoechst 33342, to differentiate between the subpopulations of X- and Y-sperm. The fluorescently stained sperm are then sex-sorted using a specialized high speed sorter, MoFlo(®) SX XDP, and collected into biologically supportive media prior to reconcentration and cryopreservation in numbers adequate for use with artificial insemination for some specie...
Pool-Anderson K, Raub RH, Warren JA.Six pairs of full-sibling Quarter Horse foals were produced by non-surgical embryo transfer and immediate rebreeding of donor mares. Each pair of donor/recipient mares consisted of one multiparous (donor) and one nulliparous (recipient) mare of similar body type and size. Milk yield was determined within 2 d of 8, 15, 22, 29 d (early lactation); 45, 60 d (midlactation); and 90, 120 d (late lactation) postpartum by the weigh-suckle-weigh method. On the following day, milk samples were collected, and foals were weighed and measured for wither height, heart girth, metacarpal length, metatarsal le...
Galli C, Colleoni S, Duchi R, Lagutina I, Lazzari G.Development of assisted reproductive technologies in horses has been relatively slow compared to other domestic species, namely ruminants and pigs. The scarce availability of abattoir ovaries and the lack of interest from horse breeders and breed associations have been the main reasons for this delay. Progressively though, the technology of oocyte maturation in vitro has been established followed by the application of ICSI to achieve fertilization in vitro. Embryo culture was initially performed in vivo, in the mare oviduct or in the surrogate sheep oviduct, to achieve the highest embryo devel...
Scherzer J, Fayrer-Hosken RA, Ray L, Hurley DJ, Heusner GL.Embryo transfer has been an inherent part of cattle breeding for more than 35 years and has also gained remarkable interest from the equine industry after several breeds allowed registration of more than one foal per year. In both large animal species, non-surgical embryo recovery and transfer are well-established techniques. However, success rates after superovulation and cryopreservation of embryos in horses are still lagging behind those of cattle, and more research is needed to address these areas. To address the problem of freezing large equine embryos, we offer a preliminary demonstratio...
Ferreira CSC, Morais RCL, de Andrade ABP, Balaro MFA, Ribas JAS, Gomes GM, Pinna AE.The aim of this study was to evaluate whether the RI and PI values would help in choosing the best embryo recipient, and observe whether CL vascularization would influence P4 production. During the breeding season 2018/2019, the study was conducted using 35 mares, which is used for reference to collect data for the project on the day of embryo transfer. The utilized mares were divided into five groups followed by the day after ovulation, with D0 being the day of ovulation. Therefore, the five groups are as follows: D4-mares that were on the 4th post-ovulation day; D5-mares that were on the 5th...
Squires EL, McCue PM.Embryo recovery from single ovulating mares is approximately 50 per cent per estrous cycle. Superovulation could be used to increase embryo recovery and provide extra embryos for embryo freezing. This review addresses some historical approaches to superovulation, as well as examines factors that affect the response of mares to equine FSH. eCG, GnRH and inhibin vaccines have been of limited success in stimulating multiple ovulation. Numerous studies have shown that injection of equine pituitary extract (EPE) will result in three to four ovulations per estrous cycle and two embryos. A purified, ...
Pinna A, Martins G, Hamond C, Medeiros MA, de Souza GN, Lilenbaum W.The objective was to investigate potential differences between two Leptospira serovars, host-adapted (Bratislava) and incidental (Copenhageni), in causing reproductive disorders in mares. From August 2009 to March 2011, 608 adult recipient mares from eight studs located in the state of Rio de Janeiro, Brazil, were screened for leptospirosis. These mares were 3-8 years of age, of various breeds, and were managed in a semiextensive system (embryo transfer centres). According to the reproductive history of these mares, the studs were categorised as Group A (357 mares: high prevalence of reprodu...
Martinez de Andino EV, Brom-de-Luna JG, Canesin HS, Rader K, Resende HL, Ripley AM, Love CC, Hinrichs K.To assess meiotic and developmental competence after transfer of immature cumulus-oocyte complexes (COCs) to the preovulatory follicles of mares (intrafollicular oocyte transfer (IFOT)). Methods: In Experiment 1, mares received an ovulatory stimulus at IFOT. Thirty hours later, COCs were recovered from the follicle, and mature oocytes underwent ICSI and embryo culture. In Experiments 2 and 3, autologous vs. allogeneic COCs were used. The mares were inseminated and embryos were recovered. In Experiment 3, the ovulatory stimulus was administered 9 h (autologous) and 15 h (allogeneic) before IF...
Blanco ID, Devito LG, Ferreira HN, Araujo GH, Fernandes CB, Alvarenga MA, Landim-Alvarenga FC.This study examined the effect of treating mares with equine pituitary extract (EPE) alone or in combination with hCG on the recovery rate of immature follicles by transvaginal follicular aspiration (ovum pick-up; OPU). Ten normally cycling crossbred mares aged 3-15 years and weighing 350-400 kg were subjected to each of three treatments in a random sequence with each exposure to a new treatment separated by a rest cycle during which a spontaneous ovulation occurred. The treatments were (1) superovulated with 25mg EPE and treated with 2500 IU hCG, (2) superovulation with 25mg EPE, and (3) cont...
