Fertility in horses encompasses the physiological processes and factors influencing reproductive success in equine species. It involves the study of reproductive anatomy, endocrinology, and behavior, as well as the management practices that affect breeding outcomes. Key aspects include the estrous cycle, conception rates, and factors impacting stallion and mare fertility. Reproductive technologies such as artificial insemination, embryo transfer, and hormonal therapies are also explored to enhance breeding efficiency. This page compiles peer-reviewed research studies and scholarly articles that examine the biological mechanisms, management strategies, and technological advancements related to equine fertility.
Gastal EL, Gastal MO, Bergfelt DR, Ginther OJ.Follicles > or = 5 mm were ablated in pony mares by a transvaginal ultrasound-guided technique on Day 10 (ovulation = Day 0). Follicle emergence (at 15 mm, experiment 1; at 6 mm, experiment 2) and development of the new wave was monitored by transrectal ultrasound. Deviation was defined as the beginning of a marked difference in growth rates between the two largest follicles. In experiment 1, mares were grouped (n = 4 per group) into controls, ablation-controls (ablations at Day 10 only), and a two-follicle model (periodic ablation sessions so that only the two largest follicles developed)....
van Niekerk FE, van Niekerk CH.In the main experiment the total daily protein intake and quality (essential amino-acids) was varied in 4 groups of mares. The incidence of oestrus in mares during the transitional period was unaffected by protein nutrition. Ovarian activity, as evaluated by follicular development and size of the ovaries, was affected. Mares that received low-quality protein (Groups 1 and 2) had a higher number of smaller follicles (< 10 mm) that developed during the transitional period compared to mares on a high-quality protein intake (Groups 3 and 4). The mares that received the high quality protein ovulate...
Brandon CI, Srivastava PN, Heusner GL, Fayrer-Hosken RA.Acrosin, Arysulfatase A, and beta-N-acetylglucosaminidase are three key enzymes localized within the mammalian acrosome that play a pivotal role in the penetration of the oocyte. The objectives of this study were to compare two methods of enzyme extraction based on the activities of these enzymes from equine spermatozoa. Method A utilized a 0.5 M Tris-maleate buffer containing 0.1% Triton X-100 and Hyamine 2389. Method B used 0.05 M Tris-HCl, 0.05 M MgCl2 in 0.05 M Tris-maleate, followed by 0.05 M Tris-maleate containing 0.1% Triton X-100. Results indicated that acrosin was initially bound in ...
Tshewang U, Dowsett KF, Knott LM, Trigg TE.To investigate the effects of two doses (200 and 400 mg) of a water-soluble gonadotrophin-releasing hormone vaccine on the ovarian activity of 2-year-old fillies. Methods: A controlled vaccination dose rate experiment. Methods: Six 2-year-old Australian Stock Horse fillies were randomly allocated to three treatment groups; unvaccinated controls, those receiving 200 mg of the vaccine and those receiving 400 mg of the vaccine. Results: Ovarian activity of the treated fillies was suppressed at the peak of breeding season while that of untreated controls continued normally. The control fillies dis...
Heilkenbrinker T, Kossin C, Scherbarth R, Frerking H.In this paper, fertility relevant parameters which are routinely examined in practice were evaluated on the basis of their correlation to one another and their influence on the foaling rates and incidence of early embryonic death in 175 brood mares of the Hanover breeding stock. The aim was to evaluate the suitability of these parameters for inclusion in a scheme for increasing the precision of predicting the subsequent course of pregnancy, as compared to such prognoses based exclusively on the histological evaluation of the endometrium. After establishing the breeding history and completing a...
Sieme H, Klug E, Bader H.Equine ejaculates are significantly characterized by widely varying parameters especially in those of practical relevance for equine Al. Therefore it is of interest for practical purposes to get subpopulations of concentrated, vital, and competent spermatozoa from the origin ejaculates. Special preparation of the donor stallions will stabilize sperm output. Fractionated semen collection from stallions supplies sperm enriched seminal fractions very useful to work with further in semen preservation. Most important to achieve a concentrated sperm subpopulation are semen manipulations post ejacula...
Batellier F, Magistrini M, Fauquant J, Palmer E.Milk-based semen diluents are known to be practical and effective in protecting equine spermatozoa during storage. Due to complex composition of milk, the components which are beneficial or harmful to spermatozoa are unknown. To address these unknowns the effect of various milk fractions on motility of stallion spermatozoa was evaluated. The fractions tested were native phosphocaseinate (NPPC), beta-casein, whey protein concentrate (WPC), alpha-lactalbumin, beta-lactoglobulin, microfiltrate, and ultrafiltrate. The standard reference diluents were INRA 82, commercial skim milk, and Hank's salts...
Raeside JI, Christie HL.Large amounts of estrogens are secreted by the tests of the mature stallion. In a recent study by Claus et al. [Claus, Dimmick, T., Gimenez, T., Hudson, L.W., 1992. Estrogens and prostaglandin F2 alpha in the semen and blood plasma of stallions. Theriogenology 38, 687-693.], it was stated that high levels of estrogens were also present in semen. As a preliminary step to study possible implications for fertility in the stallion, we have measured estrone sulphate (E1S), the principal estrogen in blood, in both seminal plasma and spermatozoa. Semen was collected from four Standardbred stallions a...
Motton DD, Roser JF.Recent evidence in our laboratory suggests that the cause of idiopathic subfertility/infertility in breeding stallions may originate in the testes at the luteinizing hormone (LH) receptor or postreceptor level. The objective of this research was to determine if LH receptor binding activity is altered in subfertile and infertile stallions. Six fertile, three subfertile, and three infertile stallions, ages 11-23 years, were classified according to normal semen parameters and pregnancy rates and then castrated in the breeding season. Blood was collected prior to castration, and plasma was stored ...
Reinert M, Calvete JJ, Sanz L, Töpfer-Petersen E.SSP-7 is a protein originally isolated from stallion seminal plasma. It has extensive amino acid sequence homology with boar spermadhesin AWN, and, like its porcine counterpart, SSP-7 displays zona pellucida-binding activity. Strikingly, however, immunohistochemical studies presented here show that the stallion and the boar spermadhesin homologues are secreted at different places of the male genital tract. Furthermore, indirect immunofluorescence shows that the topography of SSP-7 on the surface of stallion spermatozoa is restricted to the equatorial segment, whereas boar AWN epitopes cover th...
Gravance CG, Champion Z, Liu IK, Casey PJ.The evaluation of seminal characteristics is important in the clinical detection of stallion subfertility. Conventional semen evaluation includes subjective determination of sperm concentration, motility, and gross morphology. Due to the subjectivity and variability of the manual morphology assessment, computer automated sperm morphology analyses has been developed. Computer automated sperm morphology analysis was applied in the current study to determine if the morphometric measurements of sperm heads from collected and dismount samples of the same ejaculate were similar. If the post-ejaculat...
Parlevliet JM, Bleumink-Pluym NM, Houwers DJ, Remmen JL, Sluijter FJ, Colenbrander B.Contagious equine metritis (CEM) is a sexually transmissible disease in mares. Although the disease is commonly diagnosed by culturing the causative bacterium Taylorella equigenitalis (T. equigenitalis) . false negative results do occur. A recently developed Polymerase Chain Reaction (PCR) assay, however, appeared to be much more sensitive, with initial results indicating an unexpected high incidence of the agent in selected horses. In this study, samples from 107 randomly selected mares with no clinical signs of CEM submitted for conventional culture were all negative for T. equigenitalis . b...
Dell'Aquila ME, Cho YS, Minoia P, Traina V, Fusco S, Lacalandra GM, Maritato F.Conventional IVF as well as several assisted microfertilization techniques have shown limited success in the horse. After recent positive results achieved with intracytoplasmic injection of a single spermatozoon (ICSI) in human IVF, we chose to try the method in the horse. We compared conventional IVF to ICSI by fertilization rates of oocytes with compact and expanded cumuli and by developmental potential of the resulting embryos. Cumulus-oocyte complexes (COCs) were obtained by aspirating the follicular fluid from the ovaries of slaughtered mares. Complexes showing complete cumulus investment...
Dobrinski I, Smith TT, Suarez SS, Ball BA.Interaction of equine spermatozoa with oviductal epithelial cells (OEC) prolongs sperm viability and maintains low intracellular calcium concentration ([Ca2+]i) in spermatozoa. Experiments were designed to investigate 1) whether release of spermatozoa from OEC in vitro is associated with elevated [Ca2+]i and 2) whether soluble products from OEC or direct membrane contact between spermatozoa and OEC mediates the effects of OEC on sperm [Ca2+]i. In the first experiment, changes in [Ca2+]i in spermatozoa loaded with indo-1 acetoxymethylester were determined in motile spermatozoa released from OEC...
Meyers PJ, Bowman T, Blodgett G, Conboy HS, Gimenez T, Reid MP, Taylor BC, Thayer J, Jöchle W, Trigg TE.In two separate controlled clinical trials, the efficacy and safety of 2.2 mg of the GnRH analogue deslorelin, administered subcutaneously as a short-term implant to normally cycling mares in oestrus with a dominant ovarian follicle more than 30 mm in diameter, were evaluated, using a placebo as a negative control. The oestrous cycle of each mare was followed by teasing, palpation per rectum and transrectal ultrasonography. Follicles were monitored every 24 hours by ultrasonography until ovulation occurred. The mares were either mated naturally or inseminated artificially. In trial 1, 174 mare...
Thomas PG, Ball BA, Ignotz GG, Dobrinski I, Parks JE, Currie WB.Before fertilization, equine spermatozoa adhere to oviduct epithelial cells (OEC) of the mare. The biochemical basis for this adhesion has not been determined. Our objective was to produce an antiserum to block this interaction. Ejaculated spermatozoa were subjected to nitrogen cavitation and spermatozoal plasma membranes enriched by sucrose density gradient centrifugation; membrane enrichment was confirmed by comparative alkaline phosphatase analysis, electron microscopy, and one- and two-dimensional PAGE. Periacrosomal plasma membrane was used as an immunogen for the production of an antiser...
Card CE, Manning ST, Bowman P, Leibel T.Breeding or semen collection was attempted using: natural cover, manual stimulation, artificial vagina, pharmacologic induction of ejaculation, and electroejaculation. Sperm cells were recovered from the ductus deferens and epididymides post mortem. Only semen collected ex copula by imipramine and xylazine treatment resulted in conceptions (4/5). This is the first report of pregnancies in horses from ex copula semen collection.
Irvine CH, Alexander SL.To study the mechanisms responsible for the unusually slow decline of the ovulatory LH surge in mares, secretion patterns of GnRH, LH and FSH were monitored in pituitary venous blood collected every 2 or 5 min for 10.5-18.0 h from five mares on the third (n = 4) or fifth day after ovulation (first sampling period). To determine the effectiveness of progesterone negative feedback, mares were then given a luteolytic dose of a prostaglandin analogue (PGF2 alpha) and pituitary venous sampling (every 2 or 5 min for 16 h) recommenced 20-22 h later (second sampling period). During the declining arm o...
Sosnowski J, Lechniak D, Brzozowska M, Switoński M.This paper presents the results of recovering horse oocytes by aspiration and maturation in vitro for 24, 30, 36 or 42 h. A total of 522 oocytes were recovered from 221 ovaries (2.4 per ovary) and 271 oocytes (51.9%) were selected for in vitro maturation (IVM). Oocytes were cultured in maturation medium (TCM 199 + estrus cow serum [ECS] + follicle-stimulating hormone [FSH] + 17 beta-estradiol + gentamycin). One hundred and seventy oocytes were cytogenetically analysed (68.3%). Cytogenetic analysis showed that the stage of maturation (first telophase-TI or second metaphase-MII) for fertilizatio...
Koskinen E, Marttila P, Katila T.The long-term effects of the anabolic steroid 19-norandrostenololylaurate on semen characteristics of Finnhorse colts were studied in 3 experiments. Semen was collected initially at 24 months of age and then twice a year. In experiment I, 500 mg or 100 mg of steroid per animal was given every 3rd week from 12 or 16 months to 24 months of age. In colts treated with 500 mg of anabolic steroid every 3rd week, azoospermia was observed in 3 out of 5 colts in the first semen collections, immediately after the end of treatment. The other 2 colts had low sperm numbers and a high percentage of proximal...
Kirkpatrick JF, Turner JW, Liu IK, Fayrer-Hosken R, Rutberg AT.Non-lethal management methods are required for wild equids that are protected by law and for deer inhabiting areas where lethal controls are not legal or safe. Single or multiple inoculations of porcine zona pellucida (PZP) vaccine have been delivered to wild horses and deer by means of darts. Contraceptive efficacy in horses after two inoculations ranged from 90% to 100%, and after a single inoculation ranged from 19% to 28%. Mares given a controlled-release form of the vaccine had foaling rates ranging from 7% to 20%. No detectable changes in social organization or behaviours among treated h...
Glaser AL, de Vries AA, Rottier PJ, Horzinek MC, Colenbrander B.Sero-epidemiological surveys have revealed that equine arteritis virus (EAV) is prevalent in most European countries. The virus causes sporadic cases of respiratory disease and abortion in horses, the incidence of which has increased in recent years. Mares and geldings eliminate virus after acute infection, but 30% to 60% of stallions become persistently infected. In these animals, EAV is maintained within the reproductive tract and is shed continuously in the semen. Persistent infection with EAV in stallions has no negative consequences for fertility but mares inseminated with virus-contamina...
Reilas T, Katila T, Mäkelä O, Huhtinen M, Koskinen E.Intrauterine fluid (IUF) was collected using a tampon from mid-oestrous mares (n = 57) with and without ultrasonically detectable accumulations of free intraluminal fluid. Bacteria were cultured and neutrophils counted from all samples (n = 57). Total protein concentration, trypsin-inhibitor capacity (TIC), and plasmin, beta-glucuronidase (B-Gase) and N-acetyl-beta-D-glucosaminidase (NAGase) activities were determined in 27 IUF samples. The motility of spermatozoa in the presence of IUF, IUF extended with Kenney's medium (1:1) and Kenney's medium alone was analysed in 9 samples using a Hamilto...
Reinert M, Calvete JJ, Sanz L, Mann K, Töpfer-Petersen E.The primary-structure of HSP-7, a 14-kDa protein isolated from stallion seminal plasma, has been determined, HSP-7 belongs to the spermadhesin protein family, shares 98% sequence identity with the boar seminal plasma protein AWN, and, like its boar homolog, displays zona-pellucida-binding activity. Despite these conserved structural and functional features, the equine and porcine spermadhesins differ in their topography on spermatozoa.
Araujo JF, Righini AS, Fleury JJ, Caldas MC, Costa-Neto JB, Marques N.An attempt has been made to define semen seasonality in a horse in the Southern Hemisphere. Repeated measurements of three variables in the semen were made for 36 months (Jan/90-Dec/92) in a 21-year old "Mangalarga" stallion living under natural photoperiod and temperature conditions in a farm situated in São José do Rio Pardo, São Paulo, Brazil (latitude 21 degrees) 36'S; longitude 46 degrees 53' W). The horse fed on natural pasture and a nutritionally balanced feed twice a day (11:00 and 17:00 h). Water and mineral supplement were available ad libitum. Semen was collected almost daily by ...
Ferreira-Silva JC, Basto SRL, Moura MT, Rocha JM, Freitas Neto LM, Santos Filho JP, Silva Filho ML, Oliveira MAL.The work described here aimed to verify the efficiency of different extenders for cryopreservation of equine semen using sperm motility and acrosin activity as spermatic parameters. The semen was fractioned into two equal parts and resuspended in an 11% lactose solution in a 1:1 proportion, where it remained for 20 minutes at room temperature. The semen was centrifuged at 600 g for 10 minutes, and after the second centrifugation, each pellet received the freezing extender (Merck or Zorlesco) and was loaded into 4 mL straws. Each straw was placed in liquid nitrogen vapor steam for 15 minutes ...
Parillo F, Mancuso R, Vullo C, Catone G.This work was undertaken to determine the glycoconjugates secreted by the epithelium of the prostate in the intact stallion and castrated horse using lectin histochemical procedures in conjunction with enzymatic digestion and deglycosylation treatments. Additionally, anti-5 and 13-16-cytokeratin antibodies were used to localize epithelial basal cells. In the stallion, lectin histochemistry showed the following sugar residues in the Golgi zone of the glandular cells: α-Glu/Man, α-Fuc and β-Gal included in both O- and N-linked oligosaccharides as well as β-GalNAc, GlcNAc and α-Gal, which be...
Rua MA, Quirino CR, Bartholazzi Junior A, Santoro PN, Bastos R, Ribeiro Mda S, Matos LF, Vega WH.The aim of this study was to evaluate the breeding behavior of Brazilian Pony stallions during semen collection to examine the effect of age category (AC) and month of evaluation on the characteristics of breeding behavior. Nine stallions were evaluated during the breeding and non-breeding season, 5-8 (AC1) and 9-13 years (AC2) of age. The variables evaluated were reaction time (RT), mount time one (MT1) and two (MT2), mount and ejaculation time (MEjT), mounting without erection (MWEr), mounting without ejaculation (MWEj), flehmen, kicks, bites, smells, vocalizations and serum testosterone con...
Scott MA, Liu IK, Overstreet JW, Enders AC.Uterotubal junction tissues (n=12) recovered from young nulliparous mares 4 h after insemination were examined for spermatozoa in situ using scanning electron microscopy. Mares were inseminated before ovulation with semen containing 66-85% morphologically abnormal spermatozoa and approximately 1 x 10(9) progressively motile spermatozoa. Spermatozoa were found in all the tissues and displayed a variety of relationships to the epithelium, depending on regional location, spatial constraints and epithelial surface characteristics. Spermatozoa were most abundant in the epithelial folds on the uteri...
Ginther OJ, Gastal EL, Gastal MO, Duarte LF, Beg MA.The effect of the ovarian follicles on plasma concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) before versus after the expected emergence of the ovulatory follicular wave was studied on Days 0 to 18 (Day 0=ovulation) in four groups of mares (n=6/group). In addition to a control group, all follicles >/=6mm in diameter were ablated on Days 0.5, 6.5, or 12.5 in a herd of mares with reported emergence at 6mm of the future ovulatory follicle on mean Day 10.5. Concentrations of FSH were not different between the Day-0.5 or Day-6.5 ablation groups and the correspon...
Province CA, Amann RP, Pickett BW, Squires EL.Two experiments were conducted to evaluate the effects of six extenders and three glycerol levels on the motility of sperm stored at 5 degrees C. Using a split-ejaculated design, semen from 10 dogs and 12 stallions was extended with egg-yolk-tris (EYT), egg-yolk-bicarbonate (EGB), Beltsville F-3 (BF-3), Cornell University (CUE), caprogen (CAP) and heated skim milk (SM) extenders. After cooling to 5 degrees C, additional extender containing 0% to 12% glycerol was added to provide a final concentration of 0%, 3% or 6% glycerol. Regardless of glycerol level, a higher (P<0.05) percentage of can...
Cuervo-Arango J, Claes AN, Stout TAE.The diameter of embryos recovered from mares on Day 8 after ovulation varies greatly, from as little as 130 μm to as much as 2500 μm. Several factors have been proposed to affect embryo size at recovery, one of which is the type of semen (frozen vs fresh or cooled-transported) used to inseminate the mare. In addition, it has been shown that smaller embryos (<300 μm) recovered on Day 8 are less likely than larger embryos to result in successful pregnancy after transfer. However, whether the actual age of the embryo (interval from fertilization to flushing) in relation to its size also ...
Raeside JI, Christie HL.Large amounts of estrogens are secreted by the tests of the mature stallion. In a recent study by Claus et al. [Claus, Dimmick, T., Gimenez, T., Hudson, L.W., 1992. Estrogens and prostaglandin F2 alpha in the semen and blood plasma of stallions. Theriogenology 38, 687-693.], it was stated that high levels of estrogens were also present in semen. As a preliminary step to study possible implications for fertility in the stallion, we have measured estrone sulphate (E1S), the principal estrogen in blood, in both seminal plasma and spermatozoa. Semen was collected from four Standardbred stallions a...
Claes A, Cuervo-Arango J, Colleoni S, Lazzari G, Galli C, Stout TA.The success of invitro embryo production (IVEP) in horses has increased considerably during recent years, but little is known about the effect of the speed of invitro embryo development. Blastocysts (n=390) were produced by intracytoplasmic sperm injection of IVM oocytes from warmblood mares, cryopreserved, thawed and transferred into recipient mares on Days 3, 4, 5 or 6 after ovulation. The time required for invitro-produced (IVP) embryos to reach the blastocyst stage was recorded (Day 7 vs Day 8). The likelihood of foaling was affected by the speed of invitro embryo development and recipient...
Van Huffel XM, Varner DD, Hinrichs K, Garcia MC, Strzemienski PJ, Kenney RM.A photomicrographic method for evaluation of stallion spermatozoal motility was developed, and spermatozoal image and velocity characteristics were defined. The photomicrographic method was compared with visual estimation of motility in the same semen sample over time. Using photomicrography, velocities and percentages of individual spermatozoal image characteristics were determined. Although there was a high correlation between results of the 2 methods, results of the photomicrographic method were more repeatable than were those of the visual method.
Roser JF, Hughes JP.Hormonal effects of prolonged administration of gonadotrophin-releasing hormone (GnRH) were investigated in 7 fertile stallions in winter and summer. The stallions were divided into 4 groups so that 1 animal received 0.625 micrograms of GnRH and each of 2 animals received 1.25, 2.5 or 5.0 micrograms of GnRH subcutaneously every 30 min for 5 days. Daily blood samples were collected from 5 days before to 5 days after treatment for measurement of plasma concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone (T) and oestrogen conjugates (EC). Five-minute blood...
Pozor MA, Zambrano G, Roser J, Hess R, Runyon S, Runcan E, Thomas BF, Dymock D, Macpherson ML, Troedsson MH, Kelleman A.The objective of this study was to evaluate acute endocrine effects as well as histological changes in testicular parenchyma induced by the contraceptive compound RTI-4587-073(l). Six miniature stallions were used in this experiment. The treatment group (n = 3) received one oral dose of 12.5 mg/kg of RTI-4587-073(l), and the control group (n = 3) received placebo only. The stallions' baseline parameters (semen, testicular dimensions, endocrine values) were collected and recorded for 5 weeks before treatment and for 6 weeks after treatment. Multiple blood samples were collected for endoc...
Govaere JL, Hoogewijs MK, De Schauwer C, De Vliegher S, Van Soom A, Duchateau L, de Kruif A.Deep intra-uterine insemination is commonly accepted as a routine procedure for artificial insemination in horses. The motives and principles of deep insemination are well described, but the equipment used may differ. In this trial, the efficiency of two different insemination pipettes for deep intra-uterine insemination in the mare was compared with insemination into the uterine body using commercially available frozen-thawed semen of two stallions of proven fertility. These inseminations were performed using two different doses. The semi-flexible Minitube pipette was compared with a newly de...
Heiskanen ML, Hilden L, Hyyppä S, Kangasniemi A, Pirhonen A, Mäenpää PH.The first (1 to 3) sperm-rich fractions of the ejaculate were collected from 4 stallions using an open-ended vagina. The volume of the collected fractions was 12 +/- 8 ml with a density of 475 +/- 200 million spermatozoa/ml. Before freezing, the semen was diluted with a skim-milk based extender 1:1 to 1:8 (volume of semen: volume of extender), depending on the initial sperm concentration to achieve a final concentration of 100 million/ml. The total number of spermatozoa in an insemination dose ranged from 0.7 to 1 billion spermatozoa. Within 12 h after ovulation, 48 mares were inseminated in 7...
Frietman SK, Compagnie E, Stout TAE, Jonker FH, Ter Braake F.To describe perioperative management, surgical procedure, and outcome in mares with third-degree perineal lacerations (TDPL) treated with a single-stage repair, the Utrecht repair method (URM). Methods: Retrospective study. Methods: Twenty mares with TDPL. Methods: Medical records of mares with TDPL reconstructed with a URM were reviewed for perioperative management; surgical outcome; and postoperative fertility, athletic performance, and complications. Results: Mares ranged in age from 3.5 to 11 years. Long-term follow-up was available for 13 mares. Mean duration of follow-up was 9 years ...
Fowden AL, Silver M.Epostane, a competitive inhibitor of 3 beta-HSD was administered intravenously to a pregnant mare between 292 and 330 days of gestation at doses of 1-3 mg/kg/min. Plasma progesterone concentrations fell rapidly during epostane infusion in both the artery and uterine vein and remained significantly depressed for 4-5 h after the start of infusion. The venous arterial (V-A) plasma concentration difference in progesterone across the uterus also decreased significantly in response to epostane infusion. There were no significant changes in plasma progesterone or in the V-A concentration difference i...
Lyle SK, Ferrer MS.The typical dose for insemination into the uterine body of the mare is > 300 x 10(6) progressively motile spermatozoa (PMS) and an insemination dose of > 200 x 10(6) PMS is recommended for frozen-thawed semen. Low-dose insemination techniques allow for a drastic reduction in the numbers of spermatozoa required to achieve pregnancy. Acceptable pregnancy rates can be achieved with doses ranging from 1 to 25 x 10(6) PMS in volumes ranging from 20 to 1000 microL. Two techniques have been described: hysteroscopic insemination and transrectally guided deep horn insemination using a pipette. Similar ...
Donadeu FX, Ginther OJ.Follicle growth and associated changes in circulating hormone concentrations were evaluated after follicle ablation in mares (n = 13) during four 13 day periods beginning at means of -98.5, -61.4, -26.0 and 10 days from the first ovulation and corresponding to mid-anovulatory, early-transitional, late-transitional and ovulatory periods, respectively. During each period, all follicles > 5 mm in diameter were ablated (day 0) followed by no subsequent ablations (all-follicle group) or the ablation of all follicles > 5 mm when a new follicle reached > 10 mm (0-follicle group). A follicula...
Ginther OJ.Ultrasonography was used to determine whether there is embryo reduction in mares with unilaterally fixed twins when a major portion of the vascularized area of the wall of one of the embryonic vesicles is in apposition with the wall of the adjacent vesicle, rather than with the endometrium (deprivation hypothesis). In addition, the effect of ovulatory pattern (synchronous and asynchronous) on the incidence of embryo reduction was studied. Twin vesicles were ultrasonically detected on days 11 to 15 (ovulation = day 0) and were examined daily until there was embryo reduction or until day 40. In ...
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...
Vasconcelos AB, Santana MA, Santos AM, Santoro MM, Lagares MA.Microscopy has been used in the routine evaluation of sperm metabolism. Nevertheless, it has limited capacity to preview male fertility. As calorimetry may be used to evaluate directly the metabolic activity of a biological system, the aim of this study was to use microcalorimetry as an additive method for sperm metabolism evaluation of cooled equine semen. Two ejaculates of four stallions were collected and motility, viability (eosin 3%) and membrane functional integrity (hyposmotic swelling test) of spermatozoa were evaluated. Sperm samples were processed following different protocols and th...
Pascoe RR.An instrument has been designed to measure the effective length (l) and angle of declination (a) of the vulva in the mare. The product, la, provides an index (Caslick Index) suitable for determining the necessity for Caslick's operation in mares not exhibiting the classical symptoms associated with pneumovagina. The value l showed a significant increase (P less than 0.05) with increased age in breeding mares. Studies on 9020 mares revealed that all caslicked mares, and mares with a Caslick Index of less than 150, had a significantly higher pregnancy rate than non-caslicked mares of similar age...
Waelchli RO, Betteridge KJ.Twin ovulations are common in horses, but twin pregnancies are rarely carried to term. Theories of how one or both twins is/are naturally eliminated in early pregnancy, termed 'embryo reduction', have been based on ultrasonographic, not morphological, studies. Here we describe conceptuses recovered transcervically between Days 15 and 28 from 31 twin and two triplet pregnancies. Signs of contact between conceptuses were deduced from those seen in one pair that remained attached by their capsules on Day 18. Signs were found on capsules in two of 10 pairs before or during fixation (immobilisation...
Strzemienski PJ, Sertich PL, Varner DD, Kenney RM.Stallion semen was diluted in a Hepes-supplemented buffer (CM) (10(6) spermatozoa/ml) and placed in the upper well of a Sykes-Moore chemotaxis chamber. Chambers were incubated in a humidified atmosphere (5% CO2 in air) at 37 degrees C for 1 and 2 h and spermatozoa were allowed to swim through filters with a mean pore size of 3,5 or 8 micron. Spermatozoa entered filters of all three pore sizes. Distance travelled was greater for each increase in pore size (P less than 0.01) but did not differ (P greater than 0.05) between 1 and 2h of incubation. Extended semen from stallions of different fertil...
Jacob JC, Gastal EL, Gastal MO, Carvalho GR, Beg MA, Ginther OJ.The follicle and hormone aspects of diameter deviation and development of one dominant (>/=28 mm) follicle (1DF) vs two dominant follicles (2DF) were studied in 32 ovulatory follicular waves in mares. Follicles were ranked each day as F1 (largest) to F3. The beginning of deviation was designated day 0 and preceded the first increase in the differences in diameter between F1 and F2 in the 1DF group and between a combination of F1 and F2 vs F3 in the 2DF group. One dominant follicle and 2DF developed in 21 (66%) and 11 (34%) waves, respectively. Double ovulations occurred in only one of the w...
Fawcett JA, Innan H, Tsuchiya T, Sato F.Many studies have reported that advancing age in broodmares has a negative impact on the reproductive performance of horses. However, although the ages at first and last mating vary among broodmares, it is unknown how this variation affects the correlation between age and reproductive performance in mares. Here, in order to examine the effects of the ages at first and last mating, we analyzed all recorded mating events for Thoroughbreds in Japan from 1997 to 2017. We found that the live foal birth rate of mares with a younger age at first mating indeed declined at an earlier age than those wit...
Jalim SL, McKinnon AO.To evaluate the fertility of mares bred at various intervals relative to surgical management of rectovaginal fistula (RVF). Methods: Surgical repair of RVF was performed in 28 mares at variable times relative to foaling (30 days to 24 months) and also relative to rebreeding (same cycle or delayed). Postoperative fertility was then evaluated. Results: Two mares were already pregnant at the time of surgery and 20 of 23 mares (87%) that were bred immediately prior to or following surgery conceived from their first service. When mares were bred in the same cycle as surgery, the next cycle followin...
Hoopes KH, Gradil CM, Vanderwall DK, Mason HM, Sarnecky BA, Davies CJ.There is an urgent need for practical methods of population control (i.e., contraception and/or sterilization) for free-roaming (i.e., "wild" or "feral") horses and burros on Western Public Lands in the United States. The objective of this study was to evaluate the contraceptive efficacy of a novel self-assembling three-part polymer-coated magnetic intrauterine device termed as an intrauterine POD (self-assembling; iUPOD) when there are natural breeding conditions when iUPOD use was managed by veterinary professionals with no prior experience with the device. Six mares were administered an iUP...
da Silva CMB, Cano FEM, Gaitskell-Phillips G, Vega FJP.Flow cytometry is a powerful tool for the analysis of cell samples formed of multipopulations, such as spermatozoa. In recent years, multiparametric cytometers have evolved, allowing the study of different cellular characteristics, such as protein expression, DNA analysis, or mitochondrial activity. Whether using traditional fluorescent dyes or fluorophore-conjugated antibodies, each cell or cellular component is individually stained, the sample is analyzed at high velocities, and then is displayed and interpreted in a dot-plot. We hereby describe the procedure to perform a multiparametric flo...
Cochran R, Meintjes M, Reggio B, Hylan D, Carter J, Pinto C, Paccamonti D, Graff KJ, Godke RA.In vitro fertilization in horses has been less successful than anticipated owing to: (i) the inability to collect large numbers of good quality oocytes; (ii) alterations in the zona pellucida that occur during in vitro maturation of equine oocytes; and (iii) inadequate preparation of equine sperm cells. In addition, studies in humans, mice and cattle have indicated that high concentrations of glucose in culture media may inhibit embryonic development in vitro and this may also be a problem for development of equine embryos in vitro. The aims of the present study were: (i) to achieve fertilizat...
