Reproductive technology in horses encompasses a range of scientific techniques and procedures aimed at assisting and enhancing equine reproduction. These technologies include artificial insemination, embryo transfer, and cryopreservation of gametes and embryos. They are employed to improve breeding efficiency, manage genetic diversity, and preserve valuable genetic material. Artificial insemination involves the collection and introduction of semen into the mare's reproductive tract, while embryo transfer allows for the harvesting and implantation of embryos from donor to recipient mares. Cryopreservation involves freezing and storing sperm, oocytes, or embryos for future use. This page compiles peer-reviewed research studies and scholarly articles that investigate the methodologies, applications, and outcomes of reproductive technologies in equine breeding and management.
Brand A, de Bois CH, Vandenhende R.Parenteral administration of 2.5-5 mg. of prostaglandin F2alpha to horses, 15 mg. to heifers or 25-30 mg to lactating cows and 15 mg. to sheep will induce regression of the corpus luteum (luteolysis) and a fertile oestrus within 48-72 hours. Because of their luteolytic effect prostaglandins may be used in various indications in the field of reproduction. An exception is the pig in which administration of prostaglandins does not induce luteolysis before D12 and therefore fails to induce oestrus. In horses, cattle and sheep, administration of prostaglandins during the first four days of the cycl...
van Niekerk CH, Morgenthal JC, Sanders CP, Malan JE.Progesterone concentrations were assayed by a competitive protein-binding technique
in peripheral plasma samples collected twice
daily during four oestrous cycles of three
mares, and once a day during the first seven
weeks of pregnancy in four mares. Large
variations were found in progesterone levels
between morning and evening samples on the
same day in the same mare.
The lowest progesterone concentration
was found about the time of ovulation. Within 24 hours after ovulation the progesterone
concentration increased and two peaks, one
at 5 days and another at 8 days, were found.
Be...
Younglai EV.The research studied the effect of follicular fluid and plasma on the steroid-producing activity of granulosa cells isolated from the ovaries of horses in heat. The results could potentially provide […]
Loy RG, Swan SM.Progesterone in oil solution injected into mares intramuscularly in midcycle blocked estrus and ovulation at levels of 100 mg. per day or higher. Fifty milligrams per day prevented estrus but not ovulation. The interval from end of treatment to estrus appeared to depend upon dosage, and the effects on subsequent cyclic patterns were confounded by season of the year. Neither 50 nor 100 mg. per day stopped estrus or blocked ovulation when treatment was started on day 1 of estrus. Injection of 100 mg. per day of progesterone in oil delayed postpartum estrus and ovulation, but 50 mg. per day did n...
In this study, 198 donor mares of different breeds, ages, and reproductive category were inseminated with fresh, cooled and frozen or frozen and cooled semen at the embryo transfer station or in private artificial insemination centers during 10 breeding seasons. The results of this activity were retrospectively analyzed by Pearson Chi-square test and logistic regression to evaluate factors affecting multiple ovulations, embryo recovery, embryo quality, and embryo diameter. Out of the 661 cycles, 937 ovulations were recorded (mean ovulations/cycle: 1.42 ± 0.58). Ovulation rate and incidence of...
Ginther OJ.Equine embryo mobility and cessation of mobility (fixation) provide explanations to several enigmas in reproductive biology of the pregnant mare and provide an efficient solution to the twinning problem, the bane of brood-mare owners. Embryo mobility is maximum on Days 12 to 15 (Day 0 = ovulation) while the spherical embryo is growing from 9 to 23 mm in diameter. During mobility, the embryo can be anywhere in the uterine lumen regardless of side of ovulation. Mobility solved the enigmas of how a small embryo can block luteolysis in a relatively massive uterus and why the side of ovulation do...
Gambini A, Duque Rodríguez M, Rodríguez MB, Briski O, Flores Bragulat AP, Demergassi N, Losinno L, Salamone DF.Several equids have gone extinct and many extant equids are currently considered vulnerable to critically endangered. This work aimed to evaluate whether domestic horse oocytes support preimplantation development of zebra embryos obtained by intracytoplasmic sperm injection (ICSI, zebroid) and cloning, and to study the Hippo signaling pathway during the lineage specification of trophectoderm cells and inner cell mass cells. We first showed that zebra and horse sperm cells induce porcine oocyte activation and recruit maternal SMARCA4 during pronuclear formation. SMARCA4 recruitment showed to be...
Clérico G, Taminelli G, Veronesi JC, Polola J, Pagura N, Pinto C, Sansinena M.Oocyte vitrification is considered experimental in the horse with only three live foals reported. The oxidative conditions induced by vitrification could in part explain the poor results and melatonin, a powerful antioxidant, could stimulate ROS metabolization and restore mitochondrial function in these oocytes. Our objective was to determine the oxidative status of vitrified equine oocytes and to analyze the effect of melatonin on mitochondrial-specific ROS (mROS), oocyte maturation, ICSI embryo development and viability. Immature, abattoir-derived oocytes were held for 15 h and vitrified in...
Len J, Beehan D, Eilts B, Ebrahimie E, Lyle S.The objective of the study was to investigate if reducing the seminal plasma of stallion extended semen by centrifugation once will suffice to maintain acceptable semen quality for insemination after 4 days of cool storage. Collected semen was extended to 25 × 106 sperm/mL and subjected to one of the following treatments: noncentrifuged (control), centrifuged for 10 minutes at 900 × g and 1800 × g. The supernatant was partially removed, and the sperm pellet, reconstituted and re-extended. It was then placed in a passive cooling device overnight and then transferred to a refrigerator fo...
Squires EL, McKinnon AO, Carnevale EM, Morris R, Nett TM.For embryos collected from mares 7 days after ovulation, embryo recovery for single-ovulating mares was 53% compared to 106% for double-ovulating mares. Pregnancy rates 50 days after surgical transfer were 68 and 129%, respectively. Concentrations of LH were similar during the periovulatory period for cycles which included single or double ovulations. Horse pituitary extract given for 5.5 days resulted in greater than or equal to 2 ovulations (mean 3.8) in 26 of 28 mares and 2.0 embryos were recovered per donor compared to 0.65 for controls. Non-surgical pregnancy rates for embryos collected f...
Binder H, Jakob C, Bucher P.Successful application of embryo transfer (ET) has become common practice in cattle, horses, sheep, goats and a variety of other species held in captivity. Yet in cattle only has the technique been established commercially. In 1994 more than 100,000 bovine embryos have been transferred in European countries. Important progress in transvaginal ovum pick up (OPU), in vitro production (IVP) and cryopreservation have further improved the applicability of ET. Direct transfer simplifies the procedure considerably allowing individual transfers and eliminating the need of synchronizing recipients. In ...
Ginther OJ, Bergfelt DR.Seasonally anovulatory mares were injected, i.m., twice daily with a GnRH analogue (GnRH-A), and hCG was given when the largest follicle reached 35 mm in diameter. In Exp. 1, treatment was initiated on 23 December when the largest follicle per mare was less than or equal to 17 mm. An ovulatory response (ovulation within 21 days) occurred in 17 of 30 (57%) GnRH-A-treated mares on a mean of 15.8 days. The shortest interval to ovulation in control mares (N = 10) was 57 days. The diameter of the largest follicle first increased significantly 6 days after start of treatment. In Exp. 2, treatment wa...
Gupta SK.Mammalian zona pellucida (ZP) is composed of three to four glycoproteins, which plays an important role during fertilization. Mutations in the genes encoding zona proteins are reported in women with empty follicle syndrome, degenerated oocytes and those with an abnormal or no ZP further emphasizing their relevance during fertility. Immunization with either native or recombinant ZP glycoproteins/proteins leads to curtailment of fertility in various animal species. Observed infertility is frequently associated with ovarian pathology characterized by follicular atresia and degenerative changes in...
Iuliano MF, Squires EL, Cook VM.A 2 X 2 cross-classified experiment was conducted to investigate the effect of age of equine embryo (7 vs 8 d postovulation) and method of transfer (surgical vs nonsurgical) on pregnancy rates at 50 d of gestation. Embryos were recovered 7 or 8 d postovulation using a Foley catheter and 3 liters of modified Dulbecco's phosphate-buffered saline (PBS). Upon identification, the embryos were placed in millipore-filtered PBS containing 20% heat-inactivated steer serum and maintained at room temperature until transferred. At the time of recovery, embryos were randomly assigned to be transferred eith...
Cran DG.Many tens of thousands of calves resulting from artificial insemination (AI) have been born worldwide after XY sperm separation and commercial production is underway in several countries. Accuracy of sex selection is some 90% and can be achieved both in research facilities and at AI studs in rural locations. Most facilities sort X- sperm which have also be utilised for superovulation and embryo transfer projects and for in vitro fertilisation (IVF) as well as AI. Sort rates of some 15 x 10(6) sperm/h are currently achievable and are used for low dose insemination, generally at 2 x 10(6) frozen...
Carnevale EM.Assisted reproductive techniques that are based on oocyte manipulations have gained acceptance in the equine industry. Methods to collect and handle immature or maturing oocytes have been developed, and systems to ship oocytes now allow for collection in one location and intracytoplasmic sperm injection (ICSI) in another. Subsequently, ICSI-produced embryos can be transferred onsite, shipped to another location, or cryopreserved. Methods for the collection, identification, culture, maturation, and shipment of equine oocytes are reviewed, with an emphasis on procedures from laboratories providi...
Gil L, Olaciregui M, Luño V, Malo C, González N, Martínez F.In recent years, there has been an increased interest in new preservation techniques that facilitate sperm storage and distribution, with freeze-drying (FD) having been proposed as an alternative method for sperm preservation and maintenance of genetic resources in different animal species. FD is a method in which frozen material is dried by sublimation of ice, thereby involving a direct transition from a solid (ice) to a vapour (gas) phase. One of the main advantages of FD is that nitrogen and dry ice are no longer required for the storage and shipment of frozen sperm, which can be stored at ...
Güvenc K, Reilas T, Katila T.It is unclear whether AI of mares deep into the uterine horn causes more or less inflammation of the endometrium than conventional AI. Thus, we compared uterine inflammatory reactions of mares inseminated with two different doses of frozen-thawed semen into the tip of the uterine horn (UH) ipsilateral to the preovulatory follicle with those of mares inseminated into the uterine body (UB). Thirty-two mares were assigned to one of four groups (eight mares/group): UB20=AI into UB, 20 x 10(6)sperm/0.5 mL; UB200=AI into UB, 200 x 10(6)sperm/0.5 mL; UH20=AI into UH, 20 x 10(6)sperm/0.5 mL; UH200=AI ...
Cremonesi F, Anderson K, Lange-Consiglio A.TWO METHODS HAVE BEEN DESCRIBED TO RECOVER OOCYTES FROM EQUINE FOLLICLES IN EXCISED OVARIES: aspiration and scraping. Aim of this work was to develop an effective method for collecting equine oocytes using Tuohy needle and comparing this technique to aspiration and scraping, with or without tunica albuginea removal. This hollow hypodermic needle, usually employed for inserting epidural catheters, is designed with a slightly curved tip, shaped similar to a small curette. In unpeeled ovaries, the recovery rates of Tuohy needle group was higher (P < .05) than in the 16 g needle aspiration and ...
Gobato MLM, Segabinazzi LGTM, Scheeren VFC, Bandeira RS, Freitas-Dell'Aqua CP, Dell'Aqua JA, Papa FO.Artificial insemination using cooled-transported semen has marked importance in equine breeding programs around the world, and the high value of mules has generated avid interest in donkey semen biotechnology. However, donkey semen cools poorly in commercially available equine extenders. Therefore, this study aimed to develop approaches to improve the ability of donkey semen to tolerate cooling. Ejaculates of seven donkeys (n = 21) were cooled at 5°C for 48 h in three different extenders (milk-based, SM; sodium caseinate-based, SC; or egg yolk-based, EY) in the presence or absence of seminal ...
Andrade AFC, Knox RV, Torres MA, Pavaneli APP.When preserving sperm in the liquid or cryopreserved state, seminal plasma (SP) components within ejaculates can alter fertilizing capacity of these gametes. Depending on the species or how semen is collected, volume and concentration of SP components varies considerably. The SP contains substances essential for maintenance of sperm viability and fertility; however, these components can be deleterious depending on quantity, or duration of time before there is removal of SP from sperm in semen processing. Substances that impair (e.g., BSP - bull; HSP-1 - stallion; Major seminal plasma protein P...
Bresnahan DR, Lupole RE, Stilz CR, Carnevale EM.Zona pellucida (ZP) proteins are important for fertilization and sperm binding and are closely associated with cumulus cells. Communication between cumulus and oocytes is facilitated by intracellular membrane channels composed of connexins. The extent aging impacts potential differences in fertilization and reductions in fertility is not well understood. This study characterized age-related differences in transcript abundance of ZP proteins and connexins in cells from ovarian follicles. Additionally, differences in sperm binding to oocytes from old and young mares was evaluated. For experiment...
Yang F, Li N, Liu B, Yu J, Wu S, Zhang R, Yang W, Ji C, Sun Q, Ma J, Li M, Zhou J, Zhou X, Pietrani M, Losinno L, Zeng S.With the expansion of the donkey industry, timed artificial insemination (TAI) is becoming increasingly important in the reproductive management of jennies, however, TAI has not been widely investigated in donkeys. Objective: To develop efficient TAI protocols for cooled or frozen semen in jennies, based around ovulation induction with a GnRH analogue. Methods: Experimental exploratory study. Results: In experiment 1, the effects of different GnRH analogue (deslorelin) doses, follicle diameter (FD) at induction, repeated use of a GnRH analogue, and the influence of season on induction efficien...
Seidel GE.Principles for selecting future research projects include interests of investigators, fundability, potential applications, ethical considerations, being able to formulate testable hypotheses and choosing the best models, including selection of the most appropriate species. The following 10 areas of assisted reproduction seem especially appropriate for further research: efficacious capacitation of bovine spermatozoa in vitro; improved in vitro bovine oocyte maturation; decreasing variability and increasing efficacy of bovine superovulation; improved fertility of sexed semen; improving equine IV...
O'Donnell LJ, Sheerin BR, Hendry JM, Thatcher MJ, Thatcher WW, LeBlanc MM.The mare exhibits nocturnal uterine contractions in the last 6 days of gestation. It is hypothesized that estradiol 17beta (O17beta) may be associated with the nightly increase in uterine contractions. The 24-h secretion pattern of plasma O17beta was measured in 3 pony mares in late gestation to identify changes in release as the mare neared parturition. Blood was collected weekly at 08:00 hours beginning on day 240 and every third day from day 330 until delivery. Serial blood samples were collected from each mare every 30-min for 24-h beginning on gestation day 310 and every sixth day thereaf...
Driancourt MA.In this review, the main features of folliculogenesis are summarized and compared among species. In the past few years, ultrasonography has clarified follicle growth patterns, and our understanding of follicle maturation has improved considerably. As the follicles develop towards the ovulatory stage, three features appear to be highly conserved across all species: 1) the sequence of events (recruitment, selection and dominance); 2) the sequential need for gonadotropins (FSH for recruitment, LH for dominance) and 3) the large variability of numerical parameters (number of waves per cycle, numbe...
van Niekerk CH, Morgenthal JC, Sanders CP, Malan JE.Progesterone concentrations were assayed by a competitive protein-binding technique
in peripheral plasma samples collected twice
daily during four oestrous cycles of three
mares, and once a day during the first seven
weeks of pregnancy in four mares. Large
variations were found in progesterone levels
between morning and evening samples on the
same day in the same mare.
The lowest progesterone concentration
was found about the time of ovulation. Within 24 hours after ovulation the progesterone
concentration increased and two peaks, one
at 5 days and another at 8 days, were found.
Be...
McDonnell SM.This study is part of ongoing work toward developing pharmacological methods for enhancing and inducing ejaculation in stallions with ejaculatory dysfunction or disabilities that interfere with normal breeding behavior. The objective was to evaluate a treatment regimen involving oral imipramine followed by intravenous xylazine that, in uncontrolled field clinical trials, had shown promise for a higher rate of ejaculation and fewer side effects using a more easily obtained and administered form of imipramine. Eight stallions each underwent eight trials in which treatment consisted of imipramine...
Hemberg E, Lundeheim N, Einarsson S.To minimize the number of matings/inseminations, controlled ovulation has been practised since a long time ago. A potent short-term implant, releasing the GnRH analogue deslorelin (Ovuplant((R))) has been used in Australia and North America for several years for hastening the ovulation time in mares, but the product is not registered on the European market. This study was aimed to investigate: (1) ovulation time in mares implanted with Ovuplant when the largest follicle was 42 mm or more in size, (2) repeatability of ovulation time in successive oestruses when treated with Ovuplant, (3) pregna...
Woods GL, Hillman RB, Schlafer DH.To evaluate embryo transfer as a possible method to circumvent infertility in mares, embryos from 14 normal and 14 infertile mares were collected three times and examined. Fewer flushes (p less than 0.05) from normal than infertile mares (1/42 vs 9/42) contained only abnormal embryos whereas more flushes (p less than 0.05) from normal than infertile mares contained one or more normal embryos (28/42 vs 8/42). More flushes (p less than 0.05) from normal than infertile mares contained embryos (29/42 vs 17/42). The embryo diameters (mm) at either day-7 or day-8 post ovulation were greater (p less ...
Davies Morel MC, Newcombe JR, Hinchliffe J.Delayed uterine involution is a major cause of early reproductive failure in mares. Involution is affected by mare age, and foaling to covering interval. Involution rates vary between the previously non-gravid horn (PNGH), which recovers the quicker, and the previously gravid horn (PGH). Location of a pregnancy and its likely success may, therefore, be affected by its location relative to the previous pregnancy. This study aimed to determine: (i) the location of concepti in consecutive pregnancies; (ii) whether this varies with mare age or foaling to conception interval; (iii) whether location...
