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.
Deichsel K, Pasing S, Erber R, Ille N, Palme R, Aurich J, Aurich C.The use of breeding stallions for equestrian competitions requires that fertility is not negatively affected by competition or transport to the competition site. In this study, effects of cortisol release induced by road transport (600 km), adrenocorticotropic hormone (ACTH) administration (3 × 0.5 mg synthetic ACTH) and placebo treatment on semen quality and testosterone release were investigated in Shetland stallions (N = 13) using a crossover design. Saliva for cortisol and blood for testosterone analysis were collected for 10 weeks after treatments. Semen was collected daily for 5 days di...
Scarlet D, Walter I, Hlavaty J, Aurich C.In mares, FSH and its receptor (FSHR) are essential for ovarian function. The objective of the present study was to analyse FSHR gene expression at the mRNA and protein levels in ovarian tissue from newborn and adult horses. Expression of mRNA was analysed by reverse transcription polymerase chain reaction, whereas FSHR protein was visualised by immunohistochemistry (IHC), immunofluorescence labelling (IF) and western blot. FSHR mRNA was detected in ovarian follicles and luteal tissue from adult mares, as well as in the ovaries of neonates. Follicular growth up to 4mm in diameter was already p...
Alghamdi AS, Madill S, Foster DN, Troedsson MH.When mares are inseminated repeatedly, protein molecules from the seminal plasma (SP) prevent sperm-neutrophil binding and reduced fertility. The molecule(s) responsible for sperm-neutrophil binding is not known and the identification of beneficial SP proteins is complicated by their large numbers and abundant variation. We examined several important aspects of sperm-neutrophil binding to ultimately facilitate the identification and isolation of the molecule(s) responsible. First, we raised anti-equine P-selectin antibodies to determine the involvement of this adhesion molecule in sperm-neutro...
Scheel TK, Kapoor A, Nishiuchi E, Brock KV, Yu Y, Andrus L, Gu M, Renshaw RW, Dubovi EJ, McDonough SP, Van de Walle GR, Lipkin WI, Divers TJ....Nonprimate hepacivirus (NPHV) is the closest known relative of hepatitis C virus (HCV) and its study could enrich our understanding of HCV evolution, immunity, and pathogenesis. High seropositivity is found in horses worldwide with ∼ 3% viremic. NPHV natural history and molecular virology remain largely unexplored, however. Here, we show that NPHV, like HCV, can cause persistent infection for over a decade, with high titers and negative strand RNA in the liver. NPHV is a near-universal contaminant of commercial horse sera for cell culture. The complete NPHV 3'-UTR was determined and consists...
Martínez-Boví R, Cuervo-Arango J.Haemorrhagic anovulatory follicle is the most common pathological anovulatory condition in the mare, but its cause remains unknown. An experimental model to induce luteinised unruptured follicles (LUF) with flunixin-meglumine (FM) has been developed. Luteinised unruptured follicles share similar morphological and hormonal characteristics with haemorrhagic anovulatory follicles. Objective: To test the effect of intrafollicular administration of prostaglandins PGE2 and PGF2α during the periovulatory period on ovulation and pregnancy in FM-treated mares. Methods: In vivo experiment in a crossove...
Seidel GE.Principles for selecting future research projects include interests of investigators, fundability, potential applications, ethical considerations, being able to formulate testable hypotheses and choosing the best models, including selection of the most appropriate species. The following 10 areas of assisted reproduction seem especially appropriate for further research: efficacious capacitation of bovine spermatozoa in vitro; improved in vitro bovine oocyte maturation; decreasing variability and increasing efficacy of bovine superovulation; improved fertility of sexed semen; improving equine IV...
Monthoux C, de Brot S, Jackson M, Bleul U, Walter J.Skin malformations that resembled manifestations of Ehlers-Danlos-Syndrome were described in a variety of domestic animals during the last century as cutis hyperelastica, hyperelastosis cutis, dermatosparaxis, dermal/collagen dysplasia, dermal/cutaneous asthenia or Ehlers-Danlos-like syndrome/s. In 2007, the mutation responsible for Hereditary Equine Regional Dermal Asthenia (HERDA) in Quarter Horses was discovered. Several case reports are available for similar malformations in other breeds than Quarter Horses (Draught Horses, Arabians, and Thoroughbreds) including four case reports for Warmb...
Kozdrowski R, Sikora M, Buczkowska J, Nowak M, Raś A, Dzięcioł M.The aim of this study was to ascertain if (1) the stage of reproductive cycle influences cytological results, (2) cytology obtained from an endometrial biopsy is more accurate than cytology derived using the cytobrush, and (3) different methods used for evaluation of cytological samples produce similar diagnostic results. Material was collected from 46 mares in estrus, 48 in diestrus and from 33 mares in anestrus. Smears were evaluated using two criteria. In criterion I, a total of 300cells were counted and the percentage of polymorphonuclear cells was recorded. In criterion II, the number of ...
Miller L, Woodward EM, Campos JR, Squires EL, Troedsson M.The objectives of this study were to (i) verify localization of SP22 on fresh, cooled, and frozen/thawed equine spermatozoa and to (ii) determine SP22 mRNA and protein expression in equine testicular and epididymal tissues. Immunocytochemistry and Western blots were performed on the spermatozoa samples. Northern blots and Western blots were performed on the tissue samples. The immunocytochemistry revealed the presence of SP22 in all samples tested. The fresh spermatozoa stained predominantly over the equatorial segment as did the samples cooled for 1 and 2 days. The samples cooled for 3 days, ...
Aurich C, Budik S.Although the horse is a seasonal breeding species, a considerable number of mares continue to cycle throughout autumn and winter. Slower equine embryo growth during the non-breeding season has been hypothesized, and because smaller embryo size is beneficial for cryopreservation, embryo collection outside the breeding season could be an interesting approach for the production of frozen horse embryos. In the present retrospective study, we have therefore analysed embryo recovery rates and conceptus size in mares (n = 30) throughout the year. Conceptus diameter was either size determined after co...
Morel MC, Newcombe JR, Reynolds N.The mare's reproductive system is rarely capable of sustaining multiple pregnancies to term. Multiple pregnancies largely derive from multiple ovulations, most commonly double ovulations, hence, double ovulations are of significant concern to breeders/veterinarians. Double ovulations may be synchronous or asynchronous. Asynchrony of up to 96 hours may result in two embryonic vesicles of very different sizes, which are challenging to detect at early ultrasonic pregnancy detection. This study aims to (1) document the incidence of synchronous and asynchronous double ovulation and (2) determine ...
Aurich J, Wulf M, Ille N, Erber R, von Lewinski M, Palme R, Aurich C.Analysis of salivary cortisol is increasingly used to assess stress responses in horses. Because spontaneous or experimentally induced increases in cortisol concentrations are often relatively small for stress studies, proper controls are needed. This requires an understanding of the factors affecting salivary cortisol over longer times. In this study, we have analyzed salivary cortisol concentration for 6 mo in horses (n = 94) differing in age, sex, reproductive state, and housing. Salivary cortisol followed a diurnal rhythm with the highest concentrations in the morning and a decrease throug...
Cuervo-Arango J, Mateu-Sánchez S, Aguilar JJ, Nielsen JM, Etcharren V, Vettorazzi ML, Newcombe JR.The objective of this study was to determine the effect of the interval from induced luteolysis to ovulation on fertility of mares from two different farms. At farm 1, 215 mares were inseminated with frozen/thawed semen during 513 estrous cycles over seven consecutive breeding seasons. Estrus was induced with analogues of PGF2α in 179 cycles. At farm 2, 375 embryo flushings were performed in 65 donor mares inseminated with fresh semen; of which, 327 were performed following artificial insemination after PGF-induced luteolysis. In both farms, the intervals from PGF treatment to ovulation (ITO)...
Kilgenstein HJ, Schöniger S, Schoon D, Schoon HA.After their retirement from sports, performance mares often show a poor breeding success. The objective of this study was the microscopic evaluation of endometrial biopsies of retired sports mares (n = 189) to search for alterations that may explain subfertility. Mares of this study aged 3-23 years showed endometritis (30%) and endometrosis (77%); mild forms predominated. In regard to those mares biopsied during the breeding season (n = 99), 50% had glandular differentiation disorders, i.e. glandular inactivity (8%) or irregular glandular differentiation (42%). Compared to literature d...
Botelho JH, Pessoa GO, Rocha LG, Yeste M.The present research sought to determine whether the administration of estradiol benzoate and long-acting progesterone to anovulatory recipient mares could maintain the pregnancy after embryo transfer during the autumn transitional phase. Recipient mares (n = 40) received the hormonal supplementation (treated group) whereas the other 36 served as a control. The control group consisted of mares having typical estrous cycles with ovulations, development of a viable corpus luteum and received one transferred embryo 5 days after ovulation. Hormonal administrations in the treated group started 8 da...
Ninu AR, Saxena AC, Sivanarayanan TB, Remya V, Binsila BK, Maiti SK, Zama MM.A nulliparous non-descript mare was presented with a complaint of dystocia. The mare was recumbent and physical examination revealed that the animal was in shock. There was no straining and foetal forelimbs were visible outside the vulva. The foetus was dead as there was no pedal reflex. Vaginal examination revealed anterior presentation with dorso-sacral position and rigid lateral head deviation. Pre-operatively, the mare was given 5 ml Tetanus toxoid and 3 g Ceftriaxone as intramuscular injection, and 5 ml Dexamethasone in 15 L of 5% Dextrose Normal Saline (DNS) as intravenous (i/v) infusion...
Carleton CL, Donahue JM, Marteniuk JV, Sells SF, Timoney PJ.This study was undertaken to investigate the bacterial and fungal microflora on the external genitalia of a population of healthy male donkeys in the state of Michigan, USA. The aim was to identify and determine the frequency of occurrence of these microorganisms using seven different isolation media and standard microbiological procedures. The sites (urethral fossa [fossa glandis], dorsal diverticulum of the urethral sinus, distal urethra, and penile surface) in the distal reproductive tract were cultured and each isolated microorganism identified. Ten different genera of gram-positive bacter...
Tachibana Y, Sakurai T, Bai H, Shiota K, Nambo Y, Nagaoka K, Imakawa K.Extensive studies have been conducted to characterize the unique phenomena of equine pregnancy. Most studies have focused on embryo transmigration when the embryo is covered with a mucin-like glycoprotein capsule and on the characterization of the chorionic girdle and chorionic gonadotropin (CG) secretion. However, the events preceding and following capsule disappearance have not been well studied. In this study, the mRNA expression in conceptus membranes at days 19, 21, and 25 (day 0 = day of ovulation) was analyzed by RNA-seq (SOLiD3), and transcript levels on these three days and day 13...
Accogli G, Douet C, Ambruosi B, Martino NA, Uranio MF, Deleuze S, Dell'Aquila ME, Desantis S, Goudet G.Glycoprotein oligosaccharides play major roles during reproduction, yet their function in gamete interactions is not fully elucidated. Identification and comparison of the glycan pattern in cumulus-oocyte complexes (COCs) from species with different efficiencies of in vitro spermatozoa penetration through the zona pellucida (ZP) could help clarify how oligosaccharides affect gamete interactions. We compared the expression and localization of 12 glycosidic residues in equine and porcine in vitro-matured (IVM) and preovulatory COCs by means of lectin histochemistry. The COCs glycan pattern diffe...
Weese JS, Holcombe SJ, Embertson RM, Kurtz KA, Roessner HA, Jalali M, Wismer SE.Disruptions in the gastrointestinal microbiota may trigger development of post partum colic. Objective: To determine the effects of the periparturient period on the faecal microbiome and identify associations between the faecal microbiota and post partum colic. Methods: Longitudinal case-control study. Methods: Pre- and post partum faecal samples were collected from mares on 3 farms in central Kentucky. Next generation sequencing of the V4 region of the 16S rRNA gene was performed on samples from 13 mares that developed colic, 13 mares that did not display colic and 5 nonpregnant controls. Res...
Swegen A, Curry BJ, Gibb Z, Lambourne SR, Smith ND, Aitken RJ.Stallion spermatozoa continue to present scientific and clinical challenges with regard to the biological mechanisms responsible for their survival and function. In particular, deeper understanding of sperm energy metabolism, defence against oxidative damage and cell-cell interactions should improve fertility assessment and the application of advanced reproductive technologies in the equine species. In this study, we used highly sensitive LC-MS/MS technology and sequence database analysis to identify and characterise the proteome of Percoll-isolated ejaculated equine spermatozoa, with the aim ...
Schrimpf R, Metzger J, Martinsson G, Sieme H, Distl O.In stallions, impaired acrosome reaction (IAR) may often cause subfertility. Single nucleotide polymorphisms (SNPs) within FK506-binding protein (FKBP6) seem to be associated with IAR in stallions. However, their effect on stallion fertility has not yet been quantified. Using whole-genome sequence data of seven stallions, we searched FKBP6 for mutations to perform an association study in Hanoverian stallions with estimated breeding values for the paternal component of the pregnancy rate per oestrus cycle (EBV-PAT) as target trait. Genotyping five exonic mutations within FKBP6 revealed a signif...
Alves KA, Alves BG, Rocha CD, Visonná M, Mohallem RF, Gastal MO, Jacomini JO, Beletti ME, Figueiredo JR, Gambarini ML, Gastal EL.Regardless of species, advances in preantral follicle culture and cryopreservation and transplant of ovarian tissue techniques are dependent on the number and density of preantral follicles in the ovary. This study tested the effect of different histological section thicknesses on number, classification, and density of equine preantral follicles. An ovarian fragment was obtained from 5- to 10-year-old mares (n = 14) after slaughter, and each fragment was submitted to three histological section thickness treatments: 3, 5, and 7 μm. The area (cm(2)) of each ovarian fragment was measured, and...
Oldenhof H, Heutelbeck A, Blässe AK, Bollwein H, Martinsson G, Wolkers WF, Sieme H.The aim of this study was to evaluate inter-individual variability in osmotic properties of stallion spermatozoa and its correlation with cryosurvival. In addition, temperature dependency of hypo-osmotic tolerance and membrane fluidity were studied. Stallion sperm membranes exhibited good resistance towards hypotonic stress in the 15-30 °C temperature range, whereas membrane stability was found to be decreased at 4 and 37 °C. Bull spermatozoa showed greater hypo-osmotic tolerance compared with stallion spermatozoa, especially at temperatures above 30 °C, which coincided with decreased membr...
Swegen A, Aitken RJ.Feral horses populate vast land areas and often induce significant ecological and economic damage throughout the landscape. Non-lethal population control methods are considered favourable in light of animal welfare, social and ethical considerations; however, no single effective, safe and species-specific contraceptive agent is currently available for use in free-ranging wild and feral horses. This review explores aspects of equine reproductive physiology that may provide avenues for the development of specific and long-lasting immunocontraceptive vaccines and some of the novel strategies that...
Mohanty N, Gulati BR, Kumar R, Gera S, Kumar S, Kumar P, Yadav PS.Mesenchymal stem cells (MSCs) offer promise as therapeutic aid in the repair of tendon and ligament injuries in race horses. Fetal adnexa is considered as an ideal source of MSCs due to many advantages, including non-invasive nature of isolation procedures and availability of large tissue mass for harvesting the cells. However, MSCs isolated from equine fetal adnexa have not been fully characterized due to lack of species-specific markers. Therefore, this study was carried out to isolate MSCs from equine umbilical cord blood (UCB) and characterize them using cross-reactive markers. The plastic...
Sgorbini M, Bonelli F, Marmorini P, Biagi G, Corazza M, Pasquini A.The aim of the present work was to evaluate derivated reactive oxygen metabolites (d-ROMs) and biological antioxidant potential (BAP) in mares and foals to study perinatal oxidative status. A total of 60 animals were included in the present study. Maternal and foal venous blood samples were collected immediately after delivery along with a sample drawn from one of the umbilical arteries, and plasma samples were evaluated for lactatemia, d-ROMs, and BAP. The t test for unpaired data was applied between mares versus umbilical artery blood versus foals, both for d-ROMs and BAP. The Pearson test w...
Ing NH, Brinsko SP, Curley KO, Forrest DW, Love CC, Hinrichs K, Vogelsang MM, Varner DD, Welsh TH.Testicular steroidogenesis and spermatogenesis are negatively impacted by stress-related hormones such as glucocorticoids. The effects of two injections of a therapeutic dose of dexamethasone (a synthetic glucocorticoid, 0.1mg/kg; i.v.) given 24h apart to each of three stallions were investigated and compared to three saline-injected control stallions. Dexamethasone decreased circulating concentrations of cortisol by 50% at 24h after the initial injection. Serum testosterone decreased by a maximum of 94% from 4 to 20h after the initial injection of dexamethasone. Semen parameters of the dexame...
King SS, Campbell AG, Dille EA, Roser JF, Murphy LL, Jones KL.Dopamine (DA) agonist and antagonist treatments can affect ovarian reproductive events in the mare. To support our theory that DA produces these effects by acting directly on the ovary, we analyzed equine ovarian tissues for the presence of dopamine receptor-1 (D1r) and dopamine receptor-2 (D2r) mRNA by reverse transcription polymerase chain reaction (RT-PCR) and D1r and D2r proteins by Western blot and immunohistochemistry (IHC). RT-PCR was performed on RNA isolated from ovarian cortex, medulla, granulosa/theca or corpus luteum (CL) tissues and from pituitary (D2r control) and renal artery (D...
Ohnuma K, Yokoo M, Ito K, Nambo Y, Miyake YI, Komatsu M, Takahashi J.Early pregnancy factor (EPF) is an immunosuppressive protein detected in the early pregnancy serum. We have already reported that we developed the rosette inhibition test for mare EPF and detected EPF in thoroughbreds. The aim of this study was to determine whether or not our method could be used clinically. Methods: The rosette inhibition test for equine EPF was carried out on serum from six nonpregnant and six pregnant Shetland ponies, a female and a male Chinese pony, and four nonpregnant and 13 pregnant thoroughbred mares. In the thoroughbreds sera were collected during the pregnancy perio...
Beckers KF, Gomes VCL, Crissman KR, Liu CC, Schulz CJ, Childers GW, Sones JL.Placentitis is the leading cause of infectious abortion in the horse. Additionally, it can result in weak and/or growth restricted offspring. While the etiology of ascending placentitis is well described in mares, less is known regarding the pathogenesis of other types, such as nocardioform placentitis. This study aims to identify the microbial communities in different body sites of the pregnant mare in early gestation to establish a core microbiome that may be perturbed in pathologic pregnancies such as placentitis. We hypothesize that the equine placenta harbors a distinct resident microbiom...
Franciosi F, Tessaro I, Dalbies-Tran R, Douet C, Reigner F, Deleuze S, Papillier P, Miclea I, Lodde V, Luciano AM, Goudet G.The field of assisted reproduction has been developed to treat infertility in women, companion animals, and endangered species. In the horse, assisted reproduction also allows for the production of embryos from high performers without interrupting their sports career and contributes to an increase in the number of foals from mares of high genetic value. The present manuscript describes the procedures used for collecting immature and mature oocytes from horse ovaries using ovum pick-up (OPU). These oocytes were then used to investigate the incidence of aneuploidy by adapting a protocol previous...
Rosas CT, Goodman LB, von Einem J, Osterrieder N.Infections of horses with equine herpesvirus type 1 (EHV-1) have garnered new attention over the last few years. Devastating outbreaks occurring worldwide, primarily of the neurologic form of the disease, have resulted in a reassessment of the control strategies, and particularly the prophylactic measures, that are necessary to keep the infection and spread of disease in check. Most of the available EHV-1 vaccines are based on preparations of inactivated virus, which are applied monovalently for prevention of EHV-1-caused abortion in pregnant mares or as part of multivalent vaccines to prevent...
Jacob JC, Gastal EL, Gastal MO, Carvalho GR, Beg MA, Ginther OJ.Data were collected daily from 23 mares during two consecutive interovulatory intervals (IOIs). Several significant (p < 0.05) new observations on temporal relationships were made. The FSH increase that begins before ovulation temporarily plateaued on the day of discharge of follicular fluid into the peritoneal cavity in association with ovulation. During the declining portion of the pre-ovulatory oestradiol surge, an abrupt reduction in the rate of decrease occurred in synchrony with the peak of the LH surge and is consistent with a negative effect of LH on oestradiol. Repeatability within...
Troedsson MH, Liu IK, Crabo BG.After the deposition of semen in the mare's uterus, spermatozoa must be transported to the site of fertilization, be maintained in the female tract until ovulation occurs, and be prepared to fertilize the released ovum. Sperm motility, myometrial contractions, and a spontaneous post-mating uterine inflammation are important factors for the transport and survival of spermatozoa in the mare's reproductive tract. Fertilizable sperm are present in the oviduct within 4 h after insemination. At this time, the uterus is the site of a hostile inflammatory environment. Our data suggest that spermatozoa...
Arar S, Chan KH, Quinn BA, Waelchli RO, Hayes MA, Betteridge KJ, Monteiro MA.During the second and third weeks of pregnancy, the equine conceptus expands rapidly while it is enclosed within a glycan capsule. Around day 16 of gestation, the conceptus loses its mobility in the uterus by a process termed 'fixation', coinciding with various changes in the capsule. Here, we compared the structure of the carbohydrate moieties expressed by the capsule during pre- and post-fixation periods. The glycan structures were studied by chemical analyses in combination with mass spectrometry. Capsule material from conceptuses collected before fixation (days 13-16) was observed to carry...
Linfor JJ, Meyers SA.Single-cell gel electrophoresis (SCGE), or comet assay, has the ability to detect damage at the single cell level and has not been reported for equine sperm. The ability to detect nuclear damage at the single cell level could aid in the advancement of protocols for optimal semen preservation. The goals of these experiments were to adapt this assay for use with equine sperm and to utilize the assay for determining the integrity of equine sperm DNA following treatments with storage at various decreased temperatures (-20 degrees C and 5 degrees C). Results from experiments in which sperm were fro...
Feist JD, McCullough DR.A behavioural study of feral horses was conducted on the Pryor Mountain Wild Horse Range in the western United States. All 270 horses on the Range were identified individually. The sex ratio was nearly balanced. Foal to adult female ratio was 43-2:100. Morality was concentrated among foals and old horses. Horses were organized as forty-four harem groups each with a dominant stallion, one to two immature stallions, one to three immature mares, one to three adult mares and their yearling and foal offspring, and 23 bachelor groups of one to eight stallions. Harem groups were quite stable year-rou...
Roser JF.The specific nature and relative contribution of the major hormones involved in regulation of reproductive function of the stallion are not well defined nor have paracrine or autocrine factors been identified. Over the last 12 years, our laboratory has been engaged in characterizing the hypothalamic-pituitary-testicular axis (HPT) in stallions. A number of endocrine factors and mechanisms important for normal reproductive function have been investigated. Studies investigating poor fertility in stallions suggest that a closer look at the testicular level is warranted. For a complete understandi...
Nam B, Mekuria Z, Carossino M, Li G, Zheng Y, Zhang J, Cook RF, Shuck KM, Campos JR, Squires EL, Troedsson MHT, Timoney PJ, Balasuriya UBR.Equine arteritis virus (EAV) is the causative agent of equine viral arteritis (EVA), a reproductive and respiratory disease of horses. Following natural infection, 10 to 70% of infected stallions can become carriers of EAV and continue to shed virus in the semen. In this study, sequential viruses isolated from nasal secretions, buffy coat cells, and semen of seven experimentally infected and two naturally infected EAV carrier stallions were deep sequenced to elucidate the intrahost microevolutionary process after a single transmission event. Analysis of variants from nasal secretions and buffy...
Bahrami A, Divar MR, Azari M, Kafi M.In the present study, we aimed to evaluate the possible protective effects of the nicotinic acid (NA) at three concentrations (10, 20, and 40 mM) on the equine cooled and frozen-thawed spermatozoa quality markers including viability, plasma membrane or acrosome integrity, DNA fragmentation, lipid peroxidation, and total oxidant levels. We also evaluated the effects of NA on preservation of the post-thaw sperm quality after 6 hours of cold storage before freezing. Five stallions were used for semen collections. The current experiment was repeated six times using pooled semen samples from two ...
Kirkpatrick JF, Turner A.Intensive population management by means of fertility control has been shown to change the age profile of a wild horse herd. The primary change has been an increase in the number and percent of older animals, as expected, but also the appearance of new and older age classes. An examination of direct effects of fertility control on two groups of treated animals shows a significant increase in longevity over non-treated animals that is associated with contraceptive treatment. The mean age at death (MAD) was calculated for 128 wild horses for which precise birth and death dates were known, includ...
El-Sheikh Ali H, Scoggin KE, Ruby R, Loynachan A, Boakari Y, Fernandes C, Dini P, Fedorka CE, Loux SC, Esteller-Vico A, Ball BA.Cervical remodeling is a critical component in both term and preterm labor in eutherian mammals. However, the molecular mechanisms underlying cervical remodeling remain poorly understood in the mare. The current study compared the transcriptome of the equine cervix (cervical mucosa (CM) and stroma (CS)) during placentitis (placentitis group, n = 5) and normal prepartum mares (prepartum group, n = 3) to normal pregnant mares (control group, n = 4). Transcriptome analysis identified differentially expressed genes (DEGs) during placentitis (5310 in CM and 907 in CS) and during the normal prepartu...
Alonso MA, Silva LA, Affonso FJ, Lemes KM, Celeghini ECC, Lançoni R, Carvalho HF, de Arruda RP.Establishment of pregnancy after embryo transfer is the ultimate goal of an embryo transfer program and increasing pregnancy rates and reducing pregnancy loss are mandatory. The utilization of treatments to improve conception rates in recipient mares has been the focus of several research groups over the last years and the results are controversial. Some studies using human chorionic gonadotrophin (hCG) found promising results. Our hypothesis was that hCG administration would cause an additional stimulation on luteal function, uterine and luteal vascularization and progesterone concentration, ...
Baker CB, Adams MH, McDowell KJ.Horse conceptuses were collected on Days 13, 15, 20 and 25 after ovulation. Whole conceptuses (Days 13 and 15) or extra-embryonic membranes (Days 20 and 25) were homogenized and poly-adenylated RNA (poly A RNA) was isolated by binding to oligo (dT)-cellulose. Poly A RNA (1 microgram/well) was separated by size on a denaturing 1% agarose gel and blotted onto nitrocellulose filters (northern blotting). DNA probes were prepared from plasmids containing equine alpha 1, omega 1 and omega 2 interferons and human beta actin. The presence of messenger RNA (mRNA) was detected by specific hybridization ...
Redina OE, Amstislavsky SYa , Maksimovsky LF.This study examined the developmental capacity of oocytes in DD mice after they had been injected with pregnant mares' serum gonadotrophin at different stages of the oestrous cycle. The superovulation of mature DD mice at pro-oestrus, oestrus and metoestrus resulted in a large yield of viable embryos. The proportion of abnormal embryos was highest after injection of pregnant mares' serum gonadotrophin at dioestrus. The pool of viable oocytes was most synchronized with normal development after the hormone was injected at oestrus. The results demonstrate that oocytes of different morphology coul...
Gaitskell-Phillips G, Martín-Cano FE, Ortiz-Rodríguez JM, Silva-Rodríguez A, da Silva-Álvarez E, Gil MC, Ortega-Ferrusola C, Peña FJ.Seminal plasma plays an important role in sperm physiology. Seminal plasma proteins vehiculated in microvesicles, carry RNAs and proteins with a potential role in early embryo development. Additionally, proteins present in seminal plasma participate in redox regulation and energy metabolism. In view of these facts, we hypothesized that differences in protein composition of the seminal plasma among stallions may help to explain differences in freeze-ability seen among them. Three independent ejaculates from 10 different stallions of varying breeds were frozen using standard protocols in our lab...
McKinnon AO, Squires EL, Harrison LA, Blach EL, Shideler RK.During breeding of mares, ultrasonographic detection of uterine fluid accumulations in the first postpartum ovulatory period was associated with significantly decreased pregnancy rates, when compared with rates in control mares (P less than 0.005). The previously gravid uterine horn was recognized as the larger horn, when assessed for size by ultrasonography, for a mean of 21 days (range, 15 to 25 days) after parturition. On the basis of similar measurements obtained during 3 ultrasonographic scans (5-day period), uterine involution was determined to be completed in a mean of 23 days (range, 1...
Sabeur K, Ball BA.To identify the generation of the superoxide anion by equine spermatozoa. Methods: Multiple ejaculates collected from 3 Thoroughbred stallions. Methods: Induced superoxide production by reduced nicotinamide adenine dinucleotides (NAD[P]H; ie, reduced nicotinamide adenine dinucleotide [NADH] and reduced nicotinamide adenine dinucleotide phosphate [NADPH]) was measured by use of a nitroblue tetrazolium (NBT) reduction assay on whole spermatozoa and a cytochrome c reduction assay on isolated membrane fractions of spermatozoa. Localization of superoxide generation was determined by use of NBT cyto...
Chen J, Weng Q, Chao J, Hu D, Taya K.In China, the first Przewalski's horse (Equus przewalskii) group was released in Kalamaili Ungulate Protected Area in Xinjiang, in August 2001. The objective of this study was to investigate reproduction and development of released Przewalski's horses in Xinjiang, China from 2002 to 2006. Twenty-four descendants were naturally born, average reproduction rate was 38.7%, and average survival rate of foals was 69.1% in this interim. Frequent alternation of the leading stallion and infertility in female horses due to environmental factors were main causes for the low reproduction rate. The infant ...
Bollwein H, Mayer R, Weber F, Stolla R.Transrectal color Doppler ultrasound was used for the noninvasive investigation of luteal blood flow during the estrous cycle in six mares. Color was displayed in Power-Mode, in which the number of color pixels on the ultrasound image is related to the number of moving blood cells. Three pictures with a maximum number of color pixels of the corpus luteum (CL) during an examination period of about 20 min were selected and digitized on a laptop equipped with an external frame grabber card. The intra-class correlation coefficient for the number of color pixels was 0.90. In all estrous cycles simi...
Gibbs PG, Potter GD, Blake RW, McMullan WC.Milk production was measured in fourteen Quarter Horse mares at seven stages of a 150-d lactation period. Mares were divided into two groups of seven and fed diets containing either soybean meal or soybean meal and urea as nitrogen supplements. Rations were isocaloric, contained approximately 12.5% crude protein and were fortified with vitamins and minerals. Daily milk yield was estimated by the weigh-suckle-weigh method and milk composition was determined from samples taken by hand milking. Average daily milk yield ranged from 11.8 kg in early lactation to 9.8 kg in late lactation. Difference...
Oxender WD, Noden PA, Hafs HD.On December 11, 1974, 15 seasonally anestrous mares were assigned at random to 1 of 3 experimental groups: outdoor-control, indoor-control, or indoor light-treated (a 16-hour photo-period). This experiment was terminated on April 21, 1975. The five mares in the indoor light-treated group ovulated 59.0+/-6.9 days later, which was 74 days earlier (P less than 0.01) than 2 of the 5 outdoor-controls (the other 3 ovulated after April 21 during a subsequent experiment) and 50 days earlier (P less than 0.05) than the indoor-controls. Durations of the 1st estrus for the 3 groups of mares were 13.3+/-3...
Thomson K, Eskola K, Eklund M, Suominen K, Määttä M, Junnila J, Nykäsenoja S, Niinistö K, Grönthal T, Rantala M.Extended-spectrum β-lactamase producing Enterobacterales (ESBL-E) are important causative agents for infections in humans and animals. At the Equine Veterinary Teaching Hospital of the University of Helsinki, the first infections caused by ESBL-E were observed at the end of 2011 leading to enhanced infection surveillance. Contact patients were screened for ESBL-E by culturing infection sites and rectal screening. This study was focused on describing the epidemiology and microbiological characteristics of ESBL-E from equine patients of the EVTH during 2011-2014, and analysing putative risk fac...
Kareskoski M, Venhoranta H, Virtala AM, Katila T.Artificial insemination (AI) with cooled stallion semen has increased markedly during the last decades in all countries, but fertility is often lower than when fresh semen or natural mating is used. The objective of this study was to examine field data (1634 ,cycles 523 Standardbred (SB) mares, 575 Finnhorse (FH) mares, and 90 stallions) using multivariable logistic regression for factors influencing the pregnancy rate (PR) after AI with cooled transported semen from SB and FH stallions. The PR per cycle for the material was 47%: Finnhorses 42% and Standardbreds 53%. When assessed with multiva...
Nilson JH, Bokar JA, Clay CM, Farmerie TA, Fenstermaker RA, Hamernik DL, Keri RA.Expression of the glycoprotein hormone alpha-subunit gene occurs in the pituitary of all mammals but in placenta of only primates and horses. In humans, two different elements, termed upstream regulatory element (URE) and cAMP response element (CRE), are required for placenta-specific expression of the alpha-subunit gene. The URE binds a protein unique to placenta whereas the CRE binds a ubiquitous protein. Comparative analysis of the promoter-regulatory region of the alpha-subunit gene from a number of mammals indicates that a functional URE has been retained and suggests the potential for pl...
Fernandez-Fuertes B, Sánchez JM, Bagés-Arnal S, McDonald M, Yeste M, Lonergan P.This study aimed to determine the effect of bull seminal plasma (SP) and sperm on endometrial function. Bovine endometrial explants were incubated with: ejaculated sperm with or without SP, epididymal sperm, or SP alone. Neither ejaculated nor epididymal sperm induced differential expression of IL1A, IL1B, IL6, IL8, PTGES2, TNFA, and LIF. Interestingly, SP had a detrimental effect on endometrial RNA integrity. Addition of an RNase inactivation reagent to SP blocked this effect, evidencing a role for a SP-RNase. Because bulls deposit the ejaculate in the vagina, we hypothesized that the bovine ...
Claes AN, Ball BA.Anti-Müllerian hormone (AMH) plays a major role in sexual differentiation, Leydig cell differentiation, and folliculogenesis. In addition, AMH has clinical value in equine practice. In stallions, AMH can serve as an endocrine marker for equine cryptorchidism and as an immunohistochemical marker for Sertoli cell tumors. Considering that AMH is also an ovarian specific product, intact mares can be differentiated from ovariectomized mares. Peripheral AMH concentrations reflect the follicular population in mares, and therefore, are useful in the assessment of ovarian reserve and reproductive life...
