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.
SAVARD K.The urinary ketonic estrogens were studied at monthly intervals in five pregnant mares. Estrone and equilin appear to be the principal components and equilenin a minor constituent of the mares’ estrogens. The levels of equilin rise from the 4–5th months to equal and in some instances exceed those of estrone in the late months of pregnancy. A partition chromatographic method for the separation of the ketonic phenolic steroids of pregnant mares’ urine is described.
The effects of cryopreservation on the acrosomal status of equine spermatozoa were investigated. Ejaculates (n=10) from six stallions were processed fresh, after cooled storage at 4-6 degrees C for 24 h in either a milk-based or lactose-EDTA freezing extender and after freeze-thawing in lactose-EDTA extender in liquid nitrogen at either 5 x 10(7) or 2 x 10(8) spermatozoa ml(-1). All samples were incubated in TALP-TEST for 2 h at 39 degrees C in 5% CO2. Subsamples were challenged with calcium ionophore A23187 for 10 min. The acrosomal status of the spermatozoa was evaluated by staining the sper...
Mares were inseminated with motile spermatozoa suspended in 30-150 microliters Tyrode's medium directly onto the uterotubal papilla at the anterior tip of the uterine horn, ipsilateral to the ovary containing a dominant preovulatory follicle of > or = 35 mm in diameter, by means of a fine gamete intrafallopian transfer (GIFT) catheter passed through the working channel of a strobed light videoendoscope. Insemination of 10, 8, 25, 14, 11 and 10 mares with, respectively, 10.0, 5.0, 1.0, 0.5, 0.1 or 0.001 x 10(6) motile spermatozoa resulted in conception rates of, respectively, 60, 75, 64, 29,...
Eight mares with third-degree rectovestibular lacerations were treated by a two-stage surgical technique. The rectovestibular shelf was corrected with three parallel 'circular' continuous suture rows distributed along the longitudinal axis of the vagina, and the perineal body was reconstructed with three divergent simple continuous rows. Primary healing of the first-stage surgery occurred in all the mares. Seven of the mares completed the two-stage surgery and primary healing occurred in all of them. One of them returned to endurance racing competition and one was lost to follow-up. The other ...
The objective of this study was to enhance the in vitro sperm quality and in vivo fertility of frozen-thawed equine semen by the addition of l-carnitine (LC) to post-thawed semen. Different concentrations of LC were added to thawed samples to obtain four treatments control and 0.5, 1 and 2 mM LC. In the in vitro experiments, sperm motility and kinematics, membrane integrity and intracellular calcium ion concentration ([Ca ] ) were investigated, and the antioxidant bioactivity of LC was assessed by measuring hydrogen peroxide and nitrite concentrations (NO ). The fertility rate was assessed v...
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...
Martin-Pelaez S, Orsolini M, Verstraete M, de la Fuente A, Takahashi K, Meyers S, Dini P.Equine in vitro embryo production (IVP) offers a valuable opportunity to enhance the efficient utilization of genetically and economically valuable horses. In cases of subfertility, sudden death, emergency euthanasia, or limited sperm availability, IVP becomes the only viable option to produce offspring. Due to steadily improving success rates, IVP has become one of the most sought-after assisted reproductive techniques. The rising global demand has created a clear need for veterinarians and stallion owners to provide IVP-suitable sperm, where the selection of intact sperm for intracytoplasmic...
Derar D, Ali A, Al-Sobayil F, Refaai W.Granulosa cell tumors (GCTs) represent the most common ovarian neoplasms in mares, yet data on their epidemiology, risk factors, and clinical outcomes in Arabian horses are limited. Understanding their prevalence and diagnostic features is crucial for improving fertility management in this breed. Unassigned: Clinical records from 807 Arabian mares housed on 35 stud farms in central Saudi Arabia were retrospectively reviewed to determine the prevalence of GCT and potential risk factors, including age, parity, and anabolic steroid use. Twenty-four confirmed cases were further investigated using ...
Fresa K, Catandi GD, Gonzalez-Castro R, Omar A, Whitcomb LA, Cheng MH, Chen TW, Carnevale EM, Chicco AJ.Advancing age is associated with a decline in fertility and functional capacity, which may result in part from suboptimal nutrition and impaired mitochondrial function. Dietary essential polyunsaturated fatty acids (PUFA) are broadly recommended to mitigate weight loss and reduce risk of chronic disease in aged populations, but their effects on mitochondrial function are less clear. The present study investigated the impacts of dietary supplementation with essential omega-3 PUFA (flaxseed oil; N3) or omega-6 PUFA (corn oil, N6) on blood, muscle and follicular cell fatty acid composition and mi...
Mendoza Cerna MN, Anderson H, Avni G, Kahila Bar-Gal G, Juras R, Raudsepp T.Robertsonian translocations (ROBs) or centric fusions of acrocentric chromosomes are the most common structural chromosomal rearrangements in mammals. ROBs are of medical and veterinary concern because of associated subfertility and congenital disorders but are also of interest as a mechanism of chromosome and karyotype evolution. While ROBs are well documented in humans, mice, and cattle/bovids, they are extremely rare in horses, despite the 18 acrocentric chromosomes in the horse karyotype. Methods: We characterize the case using conventional and molecular cytogenetic approaches and DNA anal...
Otero JC, Neild DM, Ferrante AA, Gambarotta MC, Caldevilla ML.Glycerol, a penetrating cryoprotectant, is most employed for deep freezing spermatozoa. However, it can induce toxic, chemical, and osmotic effects, altering the lipid structure of the sperm membrane. Rapid glycerol addition has been demonstrated to have fewer toxic effects than its removal. Objective: To minimize both the toxic and osmotic effects of glycerol on equine sperm through post-thaw dilution using two different extenders. Methods: Samples of equine semen frozen with 5% glycerol from nine stallions were thawed, re-diluted 1:2, and incubated for 30 minutes at 22°C in Tyrodes (Tyr) an...
Vilela VMT, Zutter BM, Gomes LLO, Silva DF, Diniz JHW, Sancler-Silva YFR, Ignácio FS, Papa FO, Monteiro GA.This study investigated the effects of cholesterol-loaded cyclodextrin (CLC) before cryopreservation and the use of FertTalp (FT) after thawing on the structural and functional quality of equine spermatozoa. Methods: Two ejaculates from twelve stallions were divided into four groups: G1 (0 mg CLC), G2 (1.0 mg), G3 (1.5 mg), and G4 (2.0 mg). Post-thaw semen quality was evaluated through computer-assisted sperm analysis and flow cytometry. Results: In Experiment I, supplementation with 1.5 mg (G3) significantly improved total motility (64.9 ± 10.1 %) and progressive motility (40.5 ± 8.8 %) com...
Jones CJP, Aplin JD, Wilsher S.There is little information on non-ciliated secretory cell numbers in the equine oviduct isthmus over the course of the estrous cycle and the effect, if any, of insemination. Lectin histochemistry was used on a series of 13 oviducts taken at different stages of the estrous cycle, with and without insemination, to monitor glycosylation changes and the distribution of secretory cells characterised by a prominent cytoplasmic accumulation of glycoconjugates. There appeared to be an increase in secretory cells expressing a wide range of glycans in all specimens at estrus. One day after ovulation, o...
Khalil WA, Sharf MI, Derbala MK, Alfattah MA, Hassan MAE, Alhujaili W, El-Harairy MA, Abdelnour SA.Oxidative stress is a major contributor to male infertility. Therefore, fortifying assisted reproductive technology with nanotechnology could enhance sperm preservation. Objective: This study aimed to examine the impact of myo-inositol nano-emulsion (MINE) supplementation in semen extender on sperm quality, redox balance, semen bacteriology, apoptosis, ultrastructure, and acrosome status of chilled stallion semen. Methods: Semen samples were collected and preserved with 0 (MINE0), 1 (MINE1), and 2 (MINE2) mg of MINE/mL of extender. Results: Results revealed that extender fortified with 1 or 2 ...
Bueno VLC, Bastos HBA, Centeno LAM, Schmitt F, Larentis G, Mattos RC, Fiala-Rechsteiner S.The seminal plasma (SP), a fluid originating from the testes, epididymis, and accessory sex glands, represents 98 % of the volume of stallion ejaculate. Metabolomic analysis enables the identification of final products of metabolic pathways, providing insights into reproductive physiology. Objective: This study aimed to investigate the metabolomic profile of stallion seminal plasma and to investigate metabolic differences between stallions with high and low pregnancy rates, in order to identify potential biomarkers associated with fertility. Methods: Twenty-four Criollo stallions, were sampled...
Khalil WA, Sharf MI, Derbala MK, Hassan MAE, Abdelnour SA, El-Harairy MA.This study aims to investigate the cryoprotective effect of Omega-3 nano-emulsion (Omega-3 NE) on stallion sperm quality, kinematic parameters, acrosome status, subcellular ultrastructure, oxidative/antioxidant markers, and semen microbiota. Forty ejaculates were collected, extended, and cryopreserved from 5 fertile Pure Egyptian stallions (Equus caballus). The ejaculates were divided into five groups: a control group (without additive) and four groups supplemented with 25, 50, 100, and 200 μg of Omega-3 NE/mL. The Omega-3 NE exhibited an average particle size of 51-146 nm, a PDI of 0.58,...
Rychtarova J, Fulka H, Loi P, Fulka J.In the mouse, spermatozoa are highly resistant to DNA damage, even when frozen without cryoprotectants, and can produce offspring when subsequently used for ICSI (intracytoplasmic sperm injection). It is not known whether the same applies to other mammals as well. For example, in the horse, even conventional sperm freezing is still very problematic and frequently leads to sperm immobility. It has, however, never been tested whether sperm immobility also mirrors sperm head DNA damage, and if so, to what extent. In our study, we evaluated the damage to DNA in horse frozen and thawed motile and i...
Moroni R, Fanelli D, Maltinti S, Orefice M, Rota A, Camillo F, Melanie P, Cantile C, Miragliotta V, Pirone A, Lazzarini G, Passamonti F, Marmorini P....Equine persistent breeding-induced endometritis can lead to chronic uterine inflammation and fibrosis, reducing fertility. Intrauterine ozone (O₃) has recently been proposed as a potential treatment for mares unresponsive to conventional therapies. This case series describes O₃ treatment in eleven mares barren for at least one year despite multiple inseminations attempts. During the first oestrous cycle, low-volume uterine lavage and endometrial biopsy were performed, followed by 3 consecutive days of intrauterine O₂-O₃ gas insufflation. In the subsequent cycle, both procedures were re...
Latorre N, Gómez-Cuétara C, Cañizares E, Crespo F, Pérez-Aguilera V, Cuerda MI, Laborda-Gomariz JA, Soler AJ, Roldan ERS, Sanchez-Rodriguez A.Evaluating semen quality in Purebred Spanish Horses is essential to determine reproductive potential and optimize assisted reproductive techniques. Objective: This study compared several sperm analysis methods in Purebred Spanish Horses to standardize protocols suitable for both laboratory and field conditions. Methods: Fifteen stallions were evaluated through three ejaculates, analyzing sperm parameters using different techniques. Sperm kinematics was assessed by Sperm Computer Analyzer (SCA-CASA) or iSperm mCASA. Viability was analyzed by eosin-nigrosin-Giemsa (ENG) staining or Hoechst 33258...
The research aims to study the dynamics of reproductive system pathologies in mares of Kazakh and Mugalzhar horse breeds and their impact on the reproductive traits of the breeding stock. The object of the research was horses of the Kazakh and Mugalzhar breeds. The formation of experimental groups was carried out using the pair-analog method. It was found that the frequency of detection of infertile mares is 13.8-25.0%. Subinvolution of the uterus from the total number of infertile mares is 8.3-10.7%, endometritis - 16.6-23.3%, atony and hypotonia of the uterus - 8.3-13.3%, ovarian diseases - ...
Loncar KD, Ortis HA, Foss RR.Production of embryos via intracytoplasmic sperm injection (ICSI) is a common clinical procedure in equine practice. A recent study indicates that treatment of mares with phenylbutazone paste significantly lowers blastocyst production after ICSI of recovered oocytes. The current study was conducted to determine the effect of different methods of phenylbutazone administration on in vitro embryo production of recovered oocytes in mares. Unassigned: In study 1 (July 29 through September 18, 2024), 14 mares received either oral liquid phenylbutazone once daily for 10 days or no treatment. On the l...
Luis-Calero M, Marinaro F, Muñoz-García CC, Fernández-Hernández P, Ortiz-Rodríguez JM, Fernández-González R, Pericuesta E, Gutiérrez-Adán A....In vitro embryo production is widely used in equine clinical reproduction; however, its efficiency remains suboptimal due to the undermined developmental competence of in vitro-matured oocytes. In this work, we evaluated the effect of mare preovulatory follicular fluid (PFF) secretome supplementation during in vitro maturation (IVM) of equine oocytes recovered post-mortem. Secretome was isolated from PFF and was added to the IVM medium at concentrations of 20 µg/ml (S20) or 40 µg/ml (S40). The percentage of mature oocytes, as well as embryo cleavage, blastocyst development, and gene expr...
Pinto-Bravo P, Rebordão MR, Amaral AS, Szóstek-Mioduchowska A, Fernandes C, Galvão AM, Silva E, Alpoim-Moreira J, da Costa RPR, Skarzynski DJ....Oviduct glycoprotein 1 (OVGP1) is a key protein involved in oviductal functions. β-estradiol (E) and progesterone (P), oxytocin (OXT) and tumor necrosis factor-α (TNFα) modulate the equine oviduct function, through prostaglandin regulation. The objective was to evaluate OVGP1 expression within each equine oviduct segment (infundibulum, ampulla isthmus), throughout the estrous cycle. The in vitro effect of (i) E, P, OXT, TNFα; and (ii) spermatozoa, on oviduct OVGP1 transcription and secretion was studied. Gene transcription was assessed by real-time PCR; protein expression by western blot; ...
Dindo S, Tovar-Pascual L, Baldassarro VA, Bucci D, Mislei B, Spinaci M, Ortiz-Rodriguez JM.Nanoplastics (NP) accumulation in biological tissues and their adverse effects on fertility through inflammatory and oxidative stress responses have recently been described as consequences of global plastic pollution. However, little is known about the impact of NP on gametes. This study aimed to assess the internalization of NP and their effects on mature equine spermatozoa. Frozen-thawed ejaculates from five stallions were divided into untreated control (CTR) and samples supplemented with different concentrations (10, 50, 100 and 200 μg/mL) of 30 nm polystyrene NP. At baseline (T0), and a...
Newcombe JR, Claes AN, Cuervo-Arango J.Early embryonic loss (EEL), particularly between Days 14 and 42 of pregnancy, remains a key concern in equine reproduction. This study investigates the incidence of spontaneous luteolysis-used here as a marker of maternal recognition of pregnancy (MRP) failure-in both pregnant Thoroughbred (TB) broodmares and recipient mares carrying either in vivo-derived (IVD) or in vitro-produced (IVP) embryos. Retrospective reproductive data from 2078 pregnancies in TB and 532 pregnancies in recipients were analysed to determine the incidence and characteristics of clinical luteolysis during pregnancy. Ove...
Couto GR, Vigano DWA, Santos GDC, Allen WRT, Wilsher S.Vitrified embryos ≤300 μm give better pregnancy rates following warming and transfer than larger ones. Embryo recovery undertaken close to when the embryo enters the uterus (Day 6-6.5) helps in the recovery of embryos ≤300 μm. However, flushing early can mean missing an embryo not yet in the uterus, whereas later can result in embryos >300 μm. Objective: To evaluate if repeated embryo flushing on consecutive days from Day 6.5 would increase the number of embryos ≤300μm recovered. Methods: Retrospective case series. Methods: Four hundred and ninety-six inseminations with cooled ...
Hernández-Avilés C, Varner DD, Ramírez-Agámez L, Samper JC, Love CC.In the current study, we report the effect of different commercially available semen freezing extenders utilized for the "test-freeze" procedure for 13 years (2010-2023) as part of a commercial program of stallion sperm cryopreservation. Ejaculates obtained from sexually active and healthy stallions (n = 124) were cryopreserved using up to five commercially available semen freezing extenders (Lactose-EDTA [LE], MFR5, CryoMax LE [CMLE], CryoMax MFR5 [CMMFR5] or BotuCrio [BC]). Post-thaw sperm motility (total motility - TM [%]; progressive motility - PM [%]; and curvilinear velocity - VCL [μm...
Khorsand F, Hamali H, Qasemi-Panahi B, Tohidkia M.This study evaluated the effects of supplementation of the freezing extender with different concentrations of silymarin on the quality of frozen-thawed Arabian stallion spermatozoa. Semen samples from three stallions (1, 2, and 3) were suspended in the freezing extender without or with silymarin (0, 25 μg/mL, 50 μg/mL, 75 μg/mL, and 100 μg/mL) and cryopreserved in 0.5 mL straws. After 1 month of storage, the frozen semen samples in straws were thawed and evaluated in terms of viability, mitochondrial membrane potential, kinematic parameters, total and progressive motility, plasma membrane ...
Griffin RA, Miller K, Colyvas K, Sheridan A, De Iuliis G, Aitken RJ, Baker MA, Gibb Z, Swegen A.Exposure to systemic heat stress in male mammals adversely affects sperm production, fertility, and DNA integrity. To date, few studies have investigated this phenomenon in horses, particularly in industry-relevant environments. Therefore, this study examined the relationship between ambient climatic conditions and fertility within a population of commercially fertile stallions. Post-coital semen samples ( = 804) were collected weekly from 46 Thoroughbred stallions during two successive breeding seasons (NSW, Australia; 22 weeks total). Semen samples were processed via single-layer colloid...
Mules (Equus mulus), as sterile hybrids between mares and donkeys, present a unique uterine morphology and physiology that remains poorly characterized. This study provides the first histomorphometric evaluation and transcriptional profiling of the endometrium in adult mules. To achieve this, endometrial biopsies were analysed using quantitative stereology, histological classification (Kenney-Doig system), and qPCR of key immune-related and fibrotic genes. Histometric analyses revealed that the stratum spongiosum was the predominant component of the mule endometrium (mean volume density: 84.7...
Hegger A, Köhne M, Gerhauser I, Görgens A.A 19-year-old Oldenburg stallion was presented multiple times over the course of several months with recurrent colic signs. At each examination, an enlargement of the scrotum was noted, which could not be further specified by palpation and ultrasonographic examination. The increase in circumference was noted both on palpation and on inspection and the size remained unchanged throughout. No special findings were noted during the general examination and the special examination of the colic patient. A few months after the first onset of symptoms, a chicken egg-sized mass was palpated on the right...
Becerro-Rey L, Martín-Cano FE, Silva-Rodríguez A, Ortega-Ferrusola C, da Silva-Álvarez E, Ortiz-Placín C, Tapia JA, Gil MC, Peña FJ.Three isoforms of lactate dehydrogenase (LDH) - LDHA (cytoplasmic), LDHB (mitochondrial), and LDHC (flagellar) - have been identified and localized in stallion spermatozoa. Functional inhibition assays indicate that these three isoforms constitute a lactate shuttle of crucial importance for sperm function. Unassigned: Stallion spermatozoa use different energy sources; while oxidative phosphorylation predominates, glycolysis and beta-oxidation of fatty acids are also present. Glycolysis depends on the availability of NAD+ as an electron acceptor. During glycolysis, NAD+ is reduced to NADH. To e...
Muñoz-Jurado A, Requena F, Agüera EI, Escribano BM.Anti-Müllerian hormone (AMH) is a dimeric glycoprotein belonging to the superfamily of the transforming growth factor-β. Due to the discovery of AMH functions, relative to the ovarian function, it is being postulated as being a highly important marker in studies on mammalian reproduction. Therefore, the objective of this review was to describe the role of this hormone in different reproductive aspects of female mammals, taking women, cows, and mares as reference species. The relationship between ovarian reserve and AMH was analysed, and it has been verified that there is a relationship betwe...
