Omneity® Pellets
All-In-One Vitamin & Mineral Pellet
Topic:Reproduction
Reproduction in horses encompasses the biological processes and mechanisms involved in the breeding and development of equine offspring. This includes the study of reproductive anatomy, physiology, and endocrinology in both mares and stallions. Key areas of interest include the estrous cycle, ovulation, conception, gestation, and parturition. Researchers also examine factors influencing fertility, reproductive technologies such as artificial insemination and embryo transfer, and management practices that impact reproductive success. This page compiles peer-reviewed research studies and scholarly articles that explore the physiological, genetic, and environmental aspects of equine reproduction.
Cumulus cell DNA fragmentation as non-invasive biomarker of equine oocyte quality in in vitro embryo production. The efficiency of in vitro embryo production in animal species is constrained by the absence of practical, non-invasive biomarkers to assess oocyte quality. Cumulus cell DNA fragmentation index (CC-DFI) has been proposed as a biomarker in humans, but data in animals remain limited. Objective: This study investigated the association of CC-DFI with in vitro maturation (IVM) and intracytoplasmic sperm injection (ICSI) outcomes in horses, and its relationship with mare-related factors, autumnal transition period, cumulus cell viability, and cumulus expansion. Methods: Cumulus-oocyte complexes (COC...
Influence of Follicle Number and Reproductive Cyclicity on Mesenchymal Stromal Cell Yield Isolated From Equine Ovarian Follicular Aspirates. Follicular aspirates have emerged as an alternative source of mesenchymal stromal cells (MSC) in mares; however, factors influencing successful MSC isolation remain unclear. This study evaluated whether reproductive cyclicity and follicle count affect MSC recovery from ovum pick-up (OPU)-derived follicular aspirates. Twenty-eight OPU procedures were performed on 13 mares, and cells were cultured until passage 3. Successful MSC cultures were obtained in 15/28 procedures (53.6%), while 13 procedures (46.4%) yielded non-MSC populations. Neither reproductive status (cycling vs. anestrous) nor foll...
Layer-Specific Quantitative Assessment of Collagen Distribution in Equine Uteri Using Masson’s Trichrome and Digital Image Analysis: A Comparative Study. Equine endometrial fibrosis is a chronic and progressive equine uterine condition characterized by fibrosis that affects mares' fertility, with a wide range of fertility outcomes being reported for these mares. Therefore, assessing layer-specific collagen (COL) distribution is essential for a comprehensive understanding of endometrial remodelling and its impact on equine reproductive potential. Full-thickness uterine samples, including stratum functionalis (SF), stratum basalis (SB) and myometrium, were collected post-mortem from healthy control mares (Category I; n = 10) and those with mo...
Effect of Uncoated Magnetic Nanoparticles on Stallion Sperm Parameters: Influence of Semen Quality. The aim of this study was to evaluate the effect of uncoated, non-functionalised magnetic nanoparticles (MNPs) on stallion sperm and to determine whether these effects depend on initial semen quality. Ten cooled ejaculates from 3 stallions were exposed to different MNP concentrations ([MNPs] = 0, 5, 25, and 50 mg/mL), agitated, and exposed to an external magnet to recover the unbound sperm fraction. Ejaculates were classified as high- or low-quality groups according to initial evaluation sperm quality index (HSQi and LSQi), and the effect of [MNPs] was evaluated within groups using GLM. ...
Oxidative and Mitochondrial Status of Vitrified Equine In Vitro Matured Oocytes Using Temperature-Specific Equilibration Protocols. Cryopreservation of equine in vitro matured (IVM) oocytes remains a major challenge in assisted reproduction due to their high susceptibility to cryoinjury, including oxidative stress and mitochondrial dysfunction. The aim of this study was to evaluate the physiological status of vitrified/warmed equine IVM oocytes following vitrification using two temperature-specific equilibration protocols by assessing reactive oxygen species (ROS), intracellular glutathione (GSH) content and mitochondrial oxidative activity and distribution patterns. Oocytes were vitrified after 28 h of IVM either at 25...
Comparative Susceptibility of Donkey and Horse Sperm to Liquid-Storage Temperature. Preservation protocols for donkey sperm are based on those developed for horses, despite potential interspecific differences in cooling tolerance. This study compared horse and donkey sperm during long-term storage at 5°C and 17°C. Ejaculates from four stallions and four jacks (n = 16) were centrifuged, resuspended in skimmed milk-based extender, and stored at both temperatures. Sperm motility, plasma and acrosome membrane integrity, and morphology were evaluated after 1, 2 and 7 days. Fresh semen parameters showed no interspecific differences (p > 0.05). At 5°C, donkey sperm show...
Differential Gene Expression of Mesenchymal Stromal Cell and Granulosa Cell Markers in Equine Follicular Aspirates. Equine follicular aspirates obtained during ovum pick-up contain a heterogeneous mixture of mesenchymal stromal cells (MSC) and granulosa cells (GC). This study evaluates how selective isolation and expansion of MSC decrease GC populations. Follicular aspirates-derived cells were cultured up to passage four (P4) following a previously validated protocol. While freshly isolated follicular aspirates cells (FAC) displayed heterogeneous morphologies, early passages (P3-P4) showed a uniform, spindle-shaped phenotype compatible with MSC. Gene expression analysis by RT-qPCR revealed a marked upregula...
Effect of conditioned medium from equine Wharton’s jelly mesenchymal stem/stromal cells on cool-stored stallion semen. Artificial insemination in horses largely relies on cooled transported semen, but stallion spermatozoa are highly sensitive to cold stress, limiting storage duration. Mesenchymal stem/stromal cell-derived conditioned medium (CM) has shown protective effects on sperm in other species, yet its impact on equine semen remains unexplored. This study investigated the effects of equine Wharton's jelly-derived MSC-CM (eWJ-MSC-CM), on the quality of cooled stallion semen. Semen from five stallions of proven fertility was extended in INRA96 supplemented with 0, 5, or 15% eWJ-MSC-CM at 5 °C for 0, 24 a...
Endocrine Disorders and Their Effect on Equine Reproduction. Continuing the reproductive potential of aged horses is a request many equine practitioners may receive. Reproductive performance may be impacted by a host of age-related comorbidities such as the endocrinopathies, pituitary pars intermedia dysfunction, and equine metabolic syndrome. While limited information is known, reproductive effects described may include irregular estrous cycles, development of anovulatory follicles, increased incidence of uterine infection, or generalized infertility. Accurate diagnosis, management strategies, and monitoring remain critical for improving quality of lif...
Oocyte and Embryo Vitrification in Horses. Vitrification has emerged as a decisive technique in assisted reproductive technology, offering superior cryopreservation outcomes for both oocytes and embryos compared with traditional slow freezing. This chapter provides a comprehensive overview of the vitrification of equine oocytes and embryos, emphasizing the influence of technical factors, including cryoprotectant selection, exposure time, temperature control, and device volume, on vitrification outcomes. Biological factors such as the oocyte maturation stage, the presence of cumulus cells, and embryo size are also explored, highlighting...
Use of Sildenafil Citrate for the Treatment of Erectile Dysfunction in Stallions: First Case Reports. Pharmacological aids can be useful alternatives to enhance penile erection and/or improve ejaculatory function, thereby prolonging the reproductive life of stallions with ejaculatory disorders. This study aimed to evaluate the effects of sildenafil citrate in the treatment of erectile dysfunction and on semen quality in two aged stallions, a Quarter Horse (18 years) and a Mangalarga Marchador (25 years), presented to the Veterinary Hospital of FMVZ-UNESP, Botucatu, SP, Brazil. The treatment consisted of oral administration of sildenafil citrate at 0.2 mg/kg. Thirty minutes after administ...
Transcriptome Sequencing and Differential Expression Analysis of Ovaries from Kazakh Mares During Seasonal Quiescence and Estrus Activation. Kazakh horses are typical seasonal breeders, and ovarian activity is markedly reduced during the non-breeding period. Hormonal stimulation can induce ovarian functional responses during seasonal anestrus; however, the early ovarian transcriptional changes associated with this response remain incompletely understood. In this study, ovarian transcriptome sequencing was performed in 12 Kazakh mares examined during the seasonal anestrous period. The mares were classified into a non-hormonally stimulated seasonal quiescent group (DB, = 6) and a hormone-induced ovarian activation group (DY, = 6) f...
The Polish Konik Horse: A Multidisciplinary Review of Its Origin, Genetics, Ecology, Health, Behaviour and Reproductive Biology. The Polish Konik horse (PKH) is one of Europe's best-known native conservation breeds. Traditionally associated with the extinct Eurasian tarpan and conservation grazing, the breed has recently become the subject of multidisciplinary research encompassing genetics, ecology, health, behaviour and reproduction. This narrative review summarises current knowledge on the biological characteristics and contemporary scientific significance of the PKH. Literature published between 2005 and 2026 was identified through searches of PubMed, Scopus, Web of Science and Google Scholar and narratively synthes...
hCG promotes secondary ovulation and supplementary corpus luteum formation during early pregnancy in mares. This study evaluated whether the administration of human chorionic gonadotropin (hCG) during early pregnancy accelerates ovulatory dynamics and alters serum progesterone concentrations in mares with dominant follicles. Thirty pregnant embryo-recipient mares with follicles ≥35 mm during early gestation were randomly assigned to receive either 1500 IU hCG IV (hCG group; n = 17) or saline solution IV (control group; n = 13). Mares were monitored by serial ultrasonography to determine the ovulatory response and the interval to secondary ovulation. Serum progesterone concentrations were...
Veterinarian and breeder perspectives surrounding ovum pick-up and intracytoplasmic sperm injection in mares: A survey study. There is an ethical debate about the application of ovum pick-up (OPU) and intracytoplasmic sperm injection (ICSI) in mares. Objective: To survey the opinions of equine veterinarians and breeders of sport horses on the ethics of using OPU-ICSI in mares. Methods: Cross-sectional descriptive study. Methods: Three surveys were distributed. The first targeted breeders ('Breeder Survey') who were actively involved in sport horse breeding. The second targeted veterinarians performing OPU ('OPU-Reprovets Survey'). The third targeted general equine practitioners ('Practitioner Survey'). There were six...
Histological differences in the placenta of three mares treated for ascending bacterial placentitis compared to physiological pregnancies. Ascending bacterial placentitis is a frequent cause of late pregnancy loss in mares. The histology of placentitis has been described but mainly with a focus on inflammatory changes. In this study, we assessed several aspects beyond inflammatory processes between mares foaling close to term during treatment for placentitis and physiological pregnancies. We included placental tissue from physiological term pregnancies (group PP; n = 8) and clinical cases with confirmed ascending bacterial placentitis (group PL; n = 3). Samples were collected from several locations of the allantochorion (cerv...
Serum physiology, fecal microbiota, and metabolome signatures associated with perinatal stage transitions in Mongolian mares. Lactation is a critical reproductive trait that influences offspring survival and livestock productivity in equine production. Characterizing physiological transitions during the perinatal period can improve our understanding of how mares adapt to late gestation, parturition, and early lactation. However, in horses-a typical monogastric herbivore with unique digestive characteristics-the associations between gut microbiota and perinatal physiological adaptation, as well as related stage-associated microbial and metabolic features, remain largely uncharacterized. Unassigned: In this study, para...
Evidence-based interpretation of uterine cultures in mares: Linking bacterial growth patterns to endometrial inflammation. We evaluated uterine bacterial growth patterns and their association with endometrial inflammation (EI) in equine samples collected using uterine swabs (US) or low-volume uterine lavage (UL). A database including 1,545 US and 2,066 UL with cytological and bacteriological results was retrospectively analysed. Endometrial inflammation was defined as ≥2 polymorphonuclear cells per high-power field, and bacterial culture was considered positive when aerobic growth occurred within 48 h, with the number of bacterial isolates per sample recorded (0, 1, 2, or ≥3). Data were analysed using generali...
Ethical monitoring of ovum pick-up procedures in domestic horses: A standardised self-assessment checklist for responsible veterinary practice. Assisted reproductive technologies (ARTs) have the potential to accelerate genetic improvement in selective equine breeding programmes while addressing specific reproductive challenges. One recent assisted reproductive technique in domestic horse breeding is Ovum Pick-Up combined with Intracytoplasmic Sperm Injection (OPU-ICSI). Despite their advantages, the implementation of these new procedures, like more established breeding methods, raises ethical concerns relating to aspects like animal welfare, staff safety, professional and veterinary practice integrity, which must be monitored and asse...
Histomorphometric and Histochemical Changes in the Mare Tuba Uterina During the Oestrous Cycle and Follicular Cyst Condition. This study evaluated histomorphometric and histochemical changes in the mare tuba uterina during different reproductive stages and under follicular cyst conditions. Forty nonpregnant mares were classified into follicular, luteal, post-ovulation and follicular cyst groups (n = 10/group). Histological evaluation of the isthmus, ampulla and infundibulum was performed using haematoxylin and eosin staining, while periodic acid-Schiff (PAS) staining was used to assess epithelial secretory activity. Morphometric parameters included number of primary mucosal folds, fold length, epithelial height a...
Evaluation of a commercial multiplex immunoassay for assessing uterine inflammation in mares susceptible to persistent breeding-induced endometritis. Persistent breeding-induced endometritis (PBIE) is characterized by a prolonged and dysregulated uterine inflammatory response following breeding. Although inflammatory cytokines are central to the post-breeding immune response, their assessment in the equine uterus has historically relied largely on gene expression analyses. Multiplex immunoassays provide an opportunity to simultaneously quantify multiple cytokine proteins within uterine secretions; however, the application of equine-specific multiplex immunoassays utilizing the Luminex platform to low-volume uterine lavage (LVL) fluid remain...
Effects of the Freezing Diluent Tonicity and Prefreezing Cooling Rates on Post-Thaw Sperm Quality Markers in the Pure-Bred Arabian Stallion. Stallion semen cryopreservation remains limited by inconsistent post-thaw sperm quality and fertility. This study evaluated the effects of freezing extender effective tonicity and prefreezing cooling rate on post-thaw sperm characteristics in pure-bred Arabian stallions. In a two-phase design, ejaculates ( = 40) from 10 stallions were processed using extenders with different osmotic conditions (330, 390, and 450 mOsm/kg) and subjected to cooling durations of 45 min, 1.5 h, or 3 h. Sperm quality was assessed using CASA, functional assays, flow cytometry, transcriptomic analysis, and...
Extreme male reproductive skew limits effective population size in American Standardbred horses. Standardbred horses are widely used for harness racing in North America, Europe, Australia, and New Zealand. In the U.S., two gaits (Pacers and Trotters) are genetically differentiated at a level typical for different horse breeds. We used the complete pedigree for all registered American Standardbred foals born 1970-2014 (>200 K Trotters and > 500 K Pacers) to calculate annual and lifetime reproductive skew and its consequences for the effective number of breeders per year (Nb) and effective size per generation (Ne). With rare exceptions, females can only produce 0 or 1 foal per year, w...
The Effect of Different Extenders and Testicular Anaesthesia During Orchiectomy on Post-Thawed Spermatological Parameters of Stallion Epididymal Spermatozoa. Cryopreservation of epididymal stallion spermatozoa is a valuable tool for fertility preservation, particularly after orchiectomy. However, the potential interactions between local anaesthesia and extender composition on post-thaw spermatozoal quality remain poorly understood. This study investigated the effects of intratesticular lidocaine injection and the efficacy of various extender (egg yolk [EY] vs. lecithin [LC]) and cryoprotectant (glycerol [GLY] vs. dimethyl sulfoxide [DMSO]) combinations on stallion epididymal spermatological parameters. Using a paired factorial design, epididymal s...
The effects of clomiphene citrate on reproductive parameters in the mare. Clomiphene citrate (CC) is a longstanding human fertility drug that has yet to be investigated in horses. The objective was to evaluate effects of CC on mare reproduction. After follicle ablation on Day 0, treatment mares (n=5) received 2 grams of CC intravenously on Days 1-5 while control mares (n=4) received no treatment. Transrectal ultrasonography was performed on Days 1-5 and 8, and transvaginal oocyte aspiration occurred on Day 8. Hormones were analyzed on Days 0-5, 8, 11, and 15. Mares receiving CC exhibited higher uterine edema grades compared to control mares (P=0.009). Antral follicl...
Supplementation of IVM media with equine follicular fluid of large follicles increases blastocyst yield in equine ICSI programs. Despite advances in the use of intracytoplasmic sperm injection (ICSI) for the in vitro production of equine embryos, oocyte maturation and competence to sustain pre-implantation embryo development remain significant challenges. This study evaluated the supplementation of the in vitro maturation (IVM) medium with equine follicular fluid (eFF), obtained from young mares (2-15 years old) with oocyte-to-blastocyst conversion rates >22%, as a strategy to improve oocyte developmental competence. In the first experiment, IVM medium was supplemented with 10% eFF collected from ovarian follicles of di...
Testicular Disorders in Equids: A Case Series. Equine testicular disorders represent a diverse group of conditions that impact the longevity of a stallion's breeding career. Stud farm veterinarians should be familiar with the variety of clinical presentations and diagnostic options for these conditions. This retrospective case series reports 57 cases of testicular abnormalities in stallions and donkeys presented to the clinic for further diagnostics and treatment. These disorders included neoplasia (three unilateral and one bilateral seminoma; two Sertoli cell tumors; two Leydig cell tumors; and one malignant mixed sex cord-stromal tumor),...
Genome-Wide Identification and Characterization of the Wnt Gene Family in Donkey (Equus asinus): Phylogenetic Analysis and Expression Profiling. The gene family encodes highly conserved signaling molecules involved in vertebrate development, tissue homeostasis, and cell fate regulation. However, the evolutionary characteristics and potential biological functions of genes in the domestic donkey () remain poorly understood. In this study, we performed the first genome-wide identification and comprehensive characterization of the donkey gene family. A total of 19 genes were identified, consistent with the conserved repertoire reported in other mammalian species. Phylogenetic and synteny analyses revealed strong evolutionary conservat...
Implications of dominance deviations for reproductive and morphological traits in the genetic management of the Pura Raza Española horse. Dominance is a non-additive genetic effect involving allele interaction at the same locus. In animal breeding, it has often been ignored due to its complexity and the low accuracy of pedigree-based estimates. This study analysed dominance variance components for reproductive traits [age at first foaling (AFF), reproductive efficiency (RE), interval between first and second foaling (I12)] and morphological traits [scapulo-ischial length (SIL), dorsal sternal diameter (DSD), knee circumference (KC)] in Pura Raza Española (PRE) mares. The aim was to assess the magnitude of dominance effects acro...
Russell’s viper envenomation in a 9-month pregnant mare saved with high-dose antivenom: a first-in-world case report. Snakebite during pregnancy is an uncommon but potentially catastrophic event, with maternal and foetal outcomes closely related to the severity of envenomation. While snakebite in pregnant women has been sporadically reported and is known to be associated with significant obstetrical complications, envenomation in animals, particularly in pregnant horses, is exceedingly rare. Only a few isolated cases of snakebite in horses have been documented, and to the best of our knowledge, snakebite in a pregnant mare has not been previously reported in the medical or veterinary literature. Russell's vip...
