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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.
Effect of luteinizing hormone overstimulation on equine follicle maturation. There is evidence in several species that high circulating LH concentrations can interfere with normal follicle development and ovulation. In the mare, high LH levels after induction of luteolysis with PGF(2α) have been temporally associated with an increased incidence of anovulatory follicles. We hypothesized that a premature increase in LH levels during a follicular wave in mares would disrupt normal follicle maturation leading to ovulatory dysfunction. In experiment 1, all follicles >10 mm were ablated at midestrous cycle in pony mares followed by twice daily administration of equine LH...
Investigations on the endometrial response to intrauterine administration of N-acetylcysteine in oestrous mares. In mares, mating-induced persistent endometritis contributes to low fertility. The condition is in part related to delayed clearance of mucus accumulated within the uterine lumen. The objective of this study was to investigate the endometrial response of healthy mares to intrauterine (i.u.) treatment with N-acetylcysteine (NAC). Oestrous mares (n = 12) were randomly assigned to a treatment (TM) or control (C) group and received an i.u. infusion of 5% NAC and saline (total volume 140 ml), respectively. Endometrial biopsies were collected in five of the mares 24 h after treatment, in the rem...
Neutrophil NETs in reproduction: from infertility to preeclampsia and the possibility of fetal loss. The intention of this review is to provide an overview of the potential role of neutrophil extracellular traps (NETs) in mammalian reproduction. Neutrophil NETs appear to be involved in various stages of the reproductive cycle, starting with fertility and possibly ending with fetal loss. The first suggestion that NETs may play a role in pregnancy-related disorders was in preeclampsia, where vast numbers were detected in the intervillous space of affected placentae. The induction of NETosis involved an auto-inflammatory component, mediated by the increased release of placental micro-debris in p...
Use of a deslorelin implant for influencing sex hormones and male behaviour in a stallion – Case report. This case report describes the use of a subcutaneously applied 4.7-mg deslorelin acetate implant in a three-year-old Arabian crossbred stallion showing unwanted strong male behaviour. Following deslorelin acetate implantation the stallion showed a short transitional increase in male behaviour. A 'gelding-like' behaviour was noted 15 days (D15) after treatment. The horse was surgically castrated at the owners request at D52 after treatment. Serum testosterone, oestradiol-17β and oestrone sulphate values decreased after deslorelin acetate implantation, but serum LH and FSH levels remained uncha...
Sperm motility is lost in vitro as a consequence of mitochondrial free radical production and the generation of electrophilic aldehydes but can be significantly rescued by the presence of nucleophilic thiols. The prolonged incubation of human spermatozoa in vitro was found to induce a loss of motility associated with the activation of mitochondrial reactive oxygen species generation in the absence of any change in mitochondrial membrane potential. The increase in mitochondrial free radical production was paralleled by a loss of protein thiols and a concomitant rise in the formation of 4-hydroxynonenal, an electrophilic product of lipid peroxidation that was found to directly suppress sperm movement. These results prompted a search for nucleophiles that could counteract the action of such cytotoxic ...
Induction of double ovulation in mares using deslorelin acetate. This study aimed to determine whether deslorelin acetate could induce double ovulation in mares. In Experiment 1, eight mares were treated with prostaglandin on Day 8 (D8) after ovulation, then treated with saline or with 100 μg of a controlled-release formulation of deslorelin acetate vehicle intramuscularly (IM) every 12h from D8 after ovulation until at least two follicles reached 33 mm. At this time, ovulation was induced with 2500 IU of hCG. Artificial insemination was performed 24h after induction, and embryos were collected on the eighth day after ovulation was first detected. In Exper...
Equine spermatozoa stored in the epididymis for up to 96h at 4°C can be successfully cryopreserved and maintain their fertilization capacity. After injury or death of a valuable male, recovery of epididymal spermatozoa may be the last chance to ensure preservation of its genetic material. The objective of this research was to study the effect of sperm storage, at 4°C up to 96h, in the epididymides obtained from castrated horses and its effect on different functional sperm parameters. Aims were to study the effect of (1) sperm storage on viability and chromatin condensation; (2) pre-incubation of recovered epididymal sperm in the freezing extender, prior cryopreservation, on viability and chromatin condensation; and (3) freezing-tha...
A predictive model for reproductive performance following abortion in Thoroughbred mares. Pregnancy losses include early embryonic death (EED) and later (postimplantation) abortion. Abortions, particularly Equid herpesvirus (EHV-1) abortion epizootics, cause severe economic and production losses. The long-term effects of EHV-1 and other abortions on subsequent reproductive performance in broodmare populations, however, remain undefined. This study described the relationships of EED and abortion with the following reproductive outcomes in Thoroughbred systems: breeding efficiency, month of last breeding, subsequent pregnancy and live foal rates. A prospective cohort study in broodma...
Ovulation-inducing factor in seminal plasma: a review. Ovulation in mammals involves pulsatile release of GnRH from the hypothalamus into the hypophyseal portal system with subsequent release of LH from the anterior pituitary into systemic circulation. Elevated circulating concentrations of LH induce a cascade of events within the mature follicle, culminating in follicle rupture and evacuation. The broad classification of species as either spontaneous or induced ovulators is based on the type of stimulus responsible for eliciting GnRH release from the hypothalamus. In spontaneously ovulating species (e.g., human, sheep, cattle, horse, pigs), relea...
The effect of radio electric asymmetric conveyer treatment on sperm parameters of subfertile stallions: a pilot study. The Radio Electric Asymmetric Conveyer (REAC) has been mostly applied to treat symptoms related to psychological stress. In the study, we demonstrated the effect of REAC-Veterinary Neuro Psycho Physical Optimization (VNPPO) treatment protocol on sperm parameters of subfertile (n=11) and fertile (n=4) stallions. Subfertile stallions showed a reduced sperm concentration, progressive motility and normal morphology compared to fertile stallions. An increase in progressive sperm motility and quality of sperm morphology was found in subfertile stallions after the REAC-VNPPO treatment. The positive e...
Evaluation of foal production following intracytoplasmic sperm injection and blastocyst culture of oocytes from ovaries collected immediately before euthanasia or after death of mares under field conditions. To evaluate the efficiency of foal production following intracytoplasmic sperm injection (ICSI) and blastocyst culture of oocytes from mares that died or were euthanized under field conditions. Methods: Prospective case series. Methods: 16 mares (age, 3 to 19 years) that died or were euthanized for various causes. Methods: Ovaries were collected immediately before euthanasia (n = 10) or after death (6). Ovaries were transported to the laboratory for oocyte recovery (15 mares), or oocytes were recovered at a remote location and shipped to the laboratory (1). Oocytes underwent ICSI, and presumpt...
Kisspeptide in the estrous mare: is it an appropriate ovulation-inducing agent? Kisspeptides (KiSS) are a recently discovered family of neuropeptides with a central role in regulating the onset of reproductive function in all animals studied to date. We have established biological and physiological evidence for KiSS signaling in the mare. The objective of the current study was to evaluate the physiological and behavioral responses of mares repeatedly given the equine-specific kisspeptpin decapeptide (eKp-10, YRWNSFGLRY-NH(2)) in an effort to shorten the interovulatory period. Administration of eKp-10 (0.5 mg iv every 4 h) to mares beginning on Day 16 postovulation (Group ...
Survival rates of mares and foals and postoperative complications and fertility of mares after cesarean section: 95 cases (1986-2000). To assess survival-to-discharge rates of mares and foals and postoperative complications and fertility in mares following cesarean section (C-section). Methods: Retrospective case series. Methods: 95 mares. Methods: Medical and breeding records of mares that underwent C-section were reviewed; signalment, surgical technique, complications, survival-to-discharge rate, and pregnancy and foaling rates were recorded and evaluated. Foaling rates in the 3 years after C-section were compared with the cumulative foaling rate before C-section. Results: C-section was performed because of dystocia (n = 71...
Sex-sorting sperm using flow cytometry/cell sorting. The sex of mammalian offspring can be predetermined by flow sorting relatively pure living populations of X- and Y-chromosome-bearing sperm. This method is based on precise staining of the DNA of sperm with the nucleic acid-specific fluorophore, Hoechst 33342, to differentiate between the subpopulations of X- and Y-sperm. The fluorescently stained sperm are then sex-sorted using a specialized high speed sorter, MoFlo(®) SX XDP, and collected into biologically supportive media prior to reconcentration and cryopreservation in numbers adequate for use with artificial insemination for some specie...
Morphology of twin and triplet equine conceptuses during weeks 3 and 4 of pregnancy. 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...
Post-mating inflammatory responses of the uterus. This review attempts to summarize the current knowledge on uterine inflammatory response after mating in horses, pigs and cattle. Post-mating endometritis has been extensively studied in horses as it has been considered to cause infertility. The inflammation is known to occur also in cattle, but it has not been investigated to a similar extent. There are a number of publications about mechanisms of post-mating uterine inflammation in pigs, which seem to resemble those in horses. The major focus of this review is the horse, but relevant literature is presented also on swine and cattle. Spermato...
Reproductive performance of Thoroughbred mares in the Waikato region of New Zealand: 2. Multivariable analyses and sources of variation at the mare, stallion and stud farm level. The objective of this study was to utilise multivariable statistical methods appropriate for clustered data to identify mare-related explanatory variables that significantly affected the reproductive performance of Thoroughbred mares in the Waikato region of New Zealand. In addition, we aimed to determine the relative contribution of the mare, stallion and stud farm to reproductive performance. Methods: A prospective cohort study was performed involving five stud farms in the Waikato region of New Zealand during three consecutive breeding seasons (2006-2008). A total of 1,482 individual mares ...
Reproductive performance of Thoroughbred mares in the Waikato region of New Zealand: 1. Descriptive analyses. To describe the reproductive performance of a population of Thoroughbred mares on stud farms in the Waikato region of New Zealand. Methods: A prospective cohort study was performed involving five stud farms in the Waikato region of New Zealand during three consecutive breeding seasons (2006-2008). A total of 1,482 individual mares contributed 2007 mare years and 3,402 oestrous cycles over the three breeding seasons. Mares were served by 87 individual stallions. Results: The mean first-cycle pregnancy rate (FCPR) was 53.6%, the end-of-season pregnancy rate (SPR) was 85.3% and the foaling rate w...
Calcium-calmodulin and pH regulate protein tyrosine phosphorylation in stallion sperm. The mechanisms leading to capacitation in stallion sperm are poorly understood. The objective of our study was to define factors associated with regulation of protein tyrosine phosphorylation in stallion sperm. Stallion sperm were incubated for 4 h in modified Whitten's media with or without bicarbonate, calcium, or BSA. When sperm were incubated in air at 30×10⁶/ml at initial pH 7.25, protein tyrosine phosphorylation was detected only in medium containing 25 mM bicarbonate alone; calcium and BSA inhibited phosphorylation. Surprisingly, this inhibition did not occur when sperm were incubate...
Caseinate protects stallion sperm during semen cooling and freezing. Extenders with a defined composition containing only components with clearly protective effects on sperm during storage would be an advantage. The aims of the present work were to assess whether caseinate, improves cooled and frozen equine semen quality. Semen from six stallions were suspended with four different cooling extenders C1) Kenney extender; C2) 0.6 % caseinate; C3) 2.7 % caseinate ; and C4) C1 + 2.1 % caseinate, and frozen extenders: F1) INRA 82 extender; F2) 1.35 % caseinate; and F3) 2.7 % caseinate. Although there was no significant difference between the motility rate among the c...
Effects of oral treatment with N-acetylcysteine on the viscosity of intrauterine mucus and endometrial function in estrous mares. Persistent breeding-induced endometritis is ranked as the third most common medical problem in the adult mare and leads to enormous economic loss in horse breeding. In mares suffering from persistent breeding-induced endometritis, increased amounts of intrauterine (i.u.) fluid or viscous mucus in estrus or after breeding may act as a barrier for sperm and can contribute to low fertility. Current therapies of these mares aim to eliminate i.u. fluid and mucus by uterine lavage and/or administration of ecbolic drugs. Recently, i.u. administration of N-acetylcysteine (NAC) has been shown to suppor...
Stallion spermatozoa selected by single layer centrifugation are capable of fertilization after storage for up to 96 h at 6°C prior to artificial insemination. One of the challenges faced by equine breeders is ensuring delivery of good quality semen doses for artificial insemination when the mare is due to ovulate. Single Layer Centrifugation (SLC) has been shown to select morphologically normal spermatozoa with intact chromatin and good progressive motility from the rest of the ejaculate, and to prolong the life of these selected spermatozoa in vitro. The objective of the present study was a proof of concept, to determine whether fertilizing ability was retained in SLC-selected spermatozoa during prolonged storage. Results: Sixteen mares were insemi...
Colloidal centrifugation of stallion semen results in a reduced rate of sperm DNA fragmentation. Stallion spermatozoa recovered and examined immediately after colloidal centrifugation resulted in a higher straight-line velocity (VSL) than sperm processed using direct conventional centrifugation (p = 0.000), but there was no differences in the progressive motility or sperm DNA fragmentation (SDF) as determined by the sperm chromatin dispersion assay. However, when centrifuged spermatozoa were incubated at 37 °C for 24 h to determine the rate of SDF (r-SDF), a lower r-SDF (p = 0.0011) was observed in those sperm recovered after colloidal separation (0.5 ± 0.1%/h) compared to direct (1.2 ...
Effects of FSH and LH on ovarian and follicular blood flow, follicular growth and oocyte developmental competence in young and old mares. Objectives of the experiment were to determine the effects of mare age and gonadotropin treatments on dominant follicle vascularity, ovarian blood flow and dominant follicle growth and to associate follicular vascularity with oocyte developmental capacity. Growing follicles >30 mm from young (4-9 years) and old (>20 years) mares were assessed for blood flow using color Doppler ultrasonography before maturation induction with recombinant equine LH (eLH) and immediately prior to oocyte collection at 20-24 h after eLH. Pulsed Doppler was used to obtain resistance indices of ovarian arteries...
Uterine vascular degeneration is present throughout the uterine wall of multiparous mares. Colinearity between elastosis, endometrial grade, age and parity. Vascular degeneration is present in endometrial vessels of multiparous aged mares. The lesions associated with vascular degeneration consist of enlargement, duplication and splitting of the membrana elastica interna and perivascular deposits of elastin. However, there are no similar data available for deep myometrial vessels and the vascular layer. The objectives of the present study were to characterize the status of vasculature in full-thickness uterine necropsy samples and to correlate these findings to endometrial grade, age, and parity. Elastosis was present in myometrial vessels, as well...
The effect of administering equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG) post artificial insemination on fertility of lactating dairy cows. The objective was to evaluate the effect of equine chorionic gonadotropin (eCG) and hCG post artificial insemination (AI) on fertility of lactating dairy cows. In Experiment 1, cows were either treated with eCG on Day 22 post AI (400 IU; n = 80) or left untreated (n = 84). On Day 29, pregnant cows were either treated with hCG (2500 IU; n = 32) or left untreated (n = 36). Pregnancy and progesterone were evaluated on Days 29 and 45. In Experiment 2, cows (n = 28) were either treated with eCG on Day 22 (n = 13) or left untreated (n = 15) and either treated with hCG on Day 29 (n = 14) or left untr...
Iodixanol density gradient centrifugation for selecting stallion sperm for cold storage and cryopreservation. Density gradient centrifugation can be used for selection of sperm of superior quality and removal of seminal plasma for use in artificial insemination. In this study, the use of two-layer iodixanol density gradient centrifugation was evaluated for processing of stallion semen. The protocol includes centrifugation through a 16% iodixanol top layer of 1.090 g mL(-1) and collection of motile and intact sperm on a 30% iodixanol bottom layer of 1.165 g mL(-1). Sperm recovery and effects on sperm quality were determined during cold storage as well as after cryopreservation and compared with ordinar...
