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Topic:Fertility
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.
Myo-Inositol Nano-Emulsion for Enhancing Stallion Chilled Semen: Insights from In Vivo and In Silico Analyses of Sperm Quality, Oxidative Stress, Ultrastructure, Mitochondrial Response, and Semen Bacteriology. 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 ...
Histomorphometric Analysis of the Endometrium of Jennies (Equus asinus) and Mares (Equus caballus) in Estrus: Anatomical Differences and Possible Reproductive Implications. Assisted reproductive techniques are often extrapolated from horses to donkeys, despite poorer fertility outcomes in jennies. This issue has been attributed to unknown uterine species-specific differences. This study compared, through histomorphometry, the endometrium of jennies and mares. Endometrial biopsies (N = 12) were taken from reproductively sound jennies (n = 6) and mares (n = 6) in estrus. Histomorphometric analysis evaluated luminal (LE, µm) and glandular epithelium height (GE, µm), glandular lumen diameter (LD, µm), glandular area (GA, µm), the number of glands (#G), and glandu...
A pilot study to investigate the effect of insemination on secretory cell activity post-ovulation in the isthmus of the equine oviduct. 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...
Addition of cholesterol linked to cyclodextrin in processing of cryopreserved equine spermatozoa and addition of motility stimulants post-thaw. 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...
Equine oviduct-specific glycoprotein is modulated by hormones and sperm cells. 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; ...
A Unique Case of Mosaicism for Two Robertsonian Translocations, rob(17;27) and rob(17;29), in a Subfertile Mare (Equus caballus). 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...
Effect on equine sperm of post-thaw glycerol dilution using two different semen extenders. 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...
Impact of dietary essential fatty acids on phospholipid composition and mitochondrial function in aged mares. 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...
Histomorphometric characterization of the endometrium in mules (Equus mulus): An approach to endometritis/endometrosis. 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...
Regional variations in the morphology of the efferent ductules: a histological perspective in rats, bulls, stallions, and boars. Infertility is a global concern in both humans and domestic animals, with male factors accounting for nearly half of all cases. Among male reproductive structures, the efferent ductules play a crucial but understudied role in fertility. These tubules connect the testis to the epididymis and are primarily responsible for luminal fluid reabsorption, a process essential for sperm concentration, maturation, and transport. This study aimed to provide a comparative morphological and histological characterization of the efferent ductules in four species-rats, bulls, stallions, and boars-focusing on r...
From clinic to lab: Sperm parameters for equine in vitro embryo production. 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...
Granulosa cell tumor in Arabian mares: prevalence, risk factors, clinical and histopathological findings and outcome of surgical removal. 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 ...
L-Carnitine supplementation to the stallion semen extender attenuates the cryopreservation induced oxidative stress and ameliorates sperm functional attributes. The current study evaluated the effect of L-Carnitine supplementation to the stallion semen extender on pre-freeze and post-thaw semen quality and oxidative parameters in Marwari breed stallions. Methods: For this purpose, thirty-six semen ejaculates (6 ejaculates from each stallion) were collected using an artificial vagina (AV) from six adult Marwari stallions. The gel free semen was extended with different concentrations of L-Carnitine (LC) i.e. 0 mM (control), 2.5 mM (T1), 5 mM (T2) and 10 mM (T3). Pre-freeze and post-thaw semen evaluations were conducted for various seminal attributes and...
Transcriptomic profiling reveals similarities between equine IVF and ICSI embryos. In vitro production of equine embryos has been performed using intracytoplasmic sperm injection (ICSI) for the last two decades. Since 2022, a repeatable protocol for conventional in vitro fertilization (IVF) provides a successful alternative. However, little is known about the influence of the fertilization method on embryo quality and the transcriptomic profile. In this study, we aimed to examine differentially expressed genes (DEGs) between ICSI and IVF embryos in the horse. Therefore, ten equine sibling blastocysts, produced in vitro by either ICSI or IVF from three different mares, were s...
Incubation of Frozen-Thawed Semen Under Capacitating Conditions Supports Successful In Vitro Fertilization and Improves Intracytoplasmic Sperm Injection-Results in Horses. In 2022, a repeatable protocol for in vitro fertilization (IVF) using fresh semen was established in horses. This facilitated successful capacitation of equine semen allowing to explore novel applications. Objective: We aimed to extend this technique to IVF with frozen-thawed semen and intracytoplasmic sperm injection (ICSI), and determine the outcome parameters such as blastocyst production and euploidy rates. Methods: A total of 221 oocytes were subjected to either IVF with frozen-thawed semen, ICSI with frozen-thawed semen incubated under capacitating conditions (ICSI cap) or control ICSI w...
Nanoplastics internalization impairs mitochondrial activity in equine sperm. 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...
Intravenous clomiphene citrate pharmacokinetics in healthy mares as a first step toward use in reproduction. To investigate the IV pharmacokinetic parameters of clomiphene citrate (CC), a selective estrogen receptor modulator, in mares. Unassigned: This was an experimental study to assess the pharmacokinetic parameters of CC in the mare. Eight mares received a single 2,000-mg dose of IV CC to identify plasma concentrations over 336 hours. Following this, 6 mares received a multidose regimen of IV CC (2,000 mg, q 24 h) for 5 days to identify trough plasma concentration each day. Unassigned: CC was well tolerated, demonstrated a short elimination half-life of 4.95 ± 1.10 hours and a mean residence tim...
Incidence of spontaneous ultrasonographic regression of the corpus luteum in pregnant embryo recipients and broodmares: a field study. 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...
Exploring the Abnormal Characteristics of the Ovaries During the Estrus Period of Kazakh Horses Based on Single-Cell Transcriptome Technology. The ovary is among the earliest organs to undergo age-related degeneration, limiting the reproductive potential of elite horses and constraining the growth of the equine industry. Follicular development during estrus is a key determinant of fertility, yet the molecular mechanisms underlying its decline, particularly at the level of specific ovarian cell types, remain poorly understood in equids. Here, we constructed a single-cell transcriptomic atlas to investigate ovarian changes in Kazakh horses. Using single-cell RNA sequencing (scRNA-seq), we profiled 112,861 cells from follicle-containing...
Evaluation of a Chemically Defined, Long-Term Extender for Liquid Storage of Stallion Semen. Efficient use of stallion semen in liquid state is limited by its relatively short shelf-life. A chemically defined extender (Beyond) is now available for long-term liquid semen preservation. The objectives of the present study were to compare Beyond with milk extenders for the preservation of semen at two temperatures, and to evaluate fertility of semen cooled for 4-8 days before artificial insemination. Semen was processed using different extenders: milk, cholesterol (BotuSemen Special); milk-based (INRA 96); and Beyond. Sperm motility, membrane and acrosome integrity, and chromatin struct...
Zinc, copper and selenium deficiencies in broodmares in south-eastern Poland. Microelement deficiencies are a current problem in horse breeding, causing infertility and fetal development disorders. The aim of the study was to control the concentration of zinc, copper and selenium in the blood serum of pregnant herd mares. The study included 154 mares in the second half of pregnancy, kept in five regions of south-eastern Poland: Łęczyńsko-Włodawska Plain, Chełmskie Hills, Łukowska Plain, Beskid Niski and Działy Grabowieckie. The concentration of zinc, copper and selenium in the obtained blood serum was determined using atomic absorption spectrophotometry. The seru...
Detection of Pathogenic Leptospira DNA in Cervicovaginal Mucus of Mares With Reproductive Disorders in a Brazilian Herd. Leptospirosis is a zoonotic disease caused by pathogenic bacteria of the genus Leptospira. A lesser-known form, equine genital leptospirosis (EGL), has been identified as a chronic and often silent infection involving the colonisation of the mare's genital tract. Despite its potential impact, EGL remains underdiagnosed and poorly understood, particularly in its association with reproductive inefficiency. This study showed the presence of Leptospira spp. DNA by lipL32-PCR in the genital tract of mares with a history of reproductive disturbances. Cervicovaginal mucus samples were collected from ...
Lipopolysaccharide reduces progesterone and cytokines in equine follicular fluid without affecting oocyte development in vitro. Lipopolysaccharide (LPS) in follicular fluid impairs steroid production and oocyte developmental competence in cows and mice. This study assessed LPS concentrations in equine follicular fluid and their association with steroid and some cytokine levels. Additionally, we evaluated whether LPS exposure during in vitro maturation (IVM) affects equine oocyte developmental competence. In experiment 1, follicular fluid from large follicles (>30 mm in diameter) was collected from 16 slaughterhouse mares, and concentrations of LPS, estradiol, progesterone, TNF-α, and IL-6 were measured. In experim...
The efficacy of embryo recovery on consecutive days from Day 6.5 to obtain small embryos for vitrification. 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 cool...
Sexual arousal intensity modulates copulatory behavior and semen quality in Arabian stallions: Effects of age, origin, and collection method. Stallion sexual behavior during semen collection can be influenced by multiple factors, yet the role of sexual arousal intensity remains underexplored. Understanding how arousal modulates behavioral and physiological reproductive traits is essential for improving artificial insemination (AI) efficiency and semen quality. This study aimed to evaluate the effects of sexual arousal intensity, age, origin, and semen collection method on stallion sexual behavior and the quality of fresh and frozen semen. Unassigned: Thirteen Arabian stallions (7 Tunisian, 6 foreign parentage) aged 6-20 years (total...
[Unilateral leiomyoma in the spermatic cord – a reason for intermittent colic in stallions?]. 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...
Associations between endometrial swab bacteriology and cytology findings and live foal rates in Thoroughbred broodmares in the United Kingdom. To date, relationships between pre-covering endometrial swab cytology and bacteriology and fertility outcomes in Thoroughbred broodmares in the United Kingdom are unknown and could aid clinical decision making. Objective: To investigate associations between cytology and bacteriology findings from the last endometrial swab taken in the breeding season (15 February to 15 July) and live-foal rates (predicted mean probability of producing a live foal) in UK Thoroughbred broodmares. Methods: Retrospective cohort study. Methods: Endometrial cytology and bacteriology findings were extracted from labo...
Extracellular Vesicles Derived From Endometrial Stem Cells Preconditioned With PGE2-Reverse Myofibroblast Phenotype in Mare Endometrial Cells: A Novel Anti-Fibrotic Approach. Endometrial fibrosis in mares compromises fertility through aberrant extracellular matrix deposition and sustained myofibroblast activation. Conventional interventions fail to reverse these pathological alterations, necessitating innovative, mechanism-focused therapies. In this study, we pioneered the use of prostaglandin E2 (PGE2) preconditioning of equine endometrial-derived mesenchymal stem cells (ET-eMSCs) and their extracellular vesicles (EVs) to target fibrotic processes directly. ET-eMSCs were isolated from mare endometrial biopsies pretreated with PGE2 to enhance their anti-fibrotic se...
Butylated hydroxytoluene (BHT) improved semen quality and sperm DNA of frozen-thawed Arabian stallions preserved in modified INRA-82 extender. Alpha-tocopherol is one of the non-enzymatic lipophilic antioxidants. Butylated hydroxytoluene (BHT) is a synthetic analog with similar modes of action in protecting the cryopreserved sperms. This study hypothesized that a certain concentration of any antioxidant is suitable for improving the post-thaw semen quality of stallions. To determine the optimum BHT concentration, a synthetic antioxidant similar to vitamin E in potency and scavenging oxidative stress power in concentrations of 0.0, 0.25, 0.50, 1.0, 2.0, and 4.0 mM/ml were added to semen extender. The post-thaw sperm progressive moti...
Studies on in vitro production of equine embryos by Intracytoplasmic Sperm Injection (ICSI) using non-sorted, or sex-sorted, frozen/thawed stallion sperm: Effects on post-thaw sperm quality, cleavage and blastocyst rates, and characterization of cellular events during the first 24 hours post-fertilization via confocal microscopy. Intracytoplasmic sperm injection (ICSI) using frozen/thawed (F/T) stallion sperm is a common procedure in the equine breeding industry. Historically, sex-sorted (SS) F/T stallion sperm has yielded lower cleavage (<30 %) and blastocyst rates (<5 %) after ICSI when compared to non-sorted (NS) F/T sperm. Recently, a new technology for sperm sex-sorting (Genesis III) has been validated by a commercial company. In Experiment 1, the post-thaw quality between NS-F/T and SS-F/T stallion sperm produced with this technology was compared. The post-thaw sperm motility was higher in NS-F/T (41 %) ...
