Stallions are adult male horses that have not been gelded and are often used for breeding purposes. They exhibit distinct behavioral and physiological characteristics compared to mares and geldings. Stallions are known for their strong musculature, prominent neck, and often more pronounced mane and tail. Their behavior can be more aggressive and territorial, especially during the breeding season, as they naturally compete for mating opportunities. This topic explores the anatomy, behavior, and management practices specific to stallions, as well as their role in equine reproduction. The page provides access to peer-reviewed research studies and scholarly articles that investigate various aspects of stallion health, fertility, and behavior, contributing to the understanding and management of these horses in equine science.
Searle D, Dart AJ, Dart CM, Hodgson DR.Complications associated with equine castration are the most common cause of malpractice claims against equine practitioners in North America. An understanding of the embryological development and surgical anatomy is essential to differentiate abnormal from normal structures and to minimise complications. Castration of the normal horse can be performed using sedation and regional anaesthesia while the horse is standing, or under general anaesthesia when it is recumbent. Castration of cryptorchid horses is best performed under general anaesthesia at a surgical facility. Techniques for castratio...
Nagata S, Kurosawa M, Mima K, Nambo Y, Fujii Y, Watanabe G, Taya K.The aim of this study was to clarify the effect of anabolic steroids on the testicular endocrine function of mature stallions. Mature thoroughbred stallions were treated with 800 mg nandrolone decanoate every 3 weeks for 3 months. After the first treatment, plasma concentrations of LH, immunoreactive inhibin and testosterone decreased rapidly to the nadir. These hormones were maintained at significantly lower concentrations compared with concentrations in intact stallions. Histology of the testicular tissue indicated the arrest of advanced spermatogenesis in the seminiferous tubules and a seve...
Khalil AM, Murakami N.For the past 12 years, a study was conducted in the Misaki area (southern Kyushu Island, Japan) to investigate young males form new harems, how they acquire the mares and the factors affecting the process of new harem formation. Young males formed new harems between the ages of 3.8 and 7.6 yr, and 93% of these new harem groups were formed at the beginning of the breeding season. The most common way (87%) for young males to form a new harem was by acquiring wandering mares which had separated from their groups, whereas 13% stole unstable mares from established bands. The fact that all young mal...
Meyers SA, Rosenberger AE.Sperm hyaluronidase has been implicated in sperm penetration of the extracellular matrix of the cumulus oophorus and may play a crucial role in gamete interaction and fertility in mammals. The objectives of this study were to characterize the enzyme activity of equine sperm hyaluronidase and to investigate its cellular distribution. Zymography of stallion sperm plasma membrane extracts was used to identify hyaluronidase activity in protein bands. Affinity-purified polyclonal IgG raised against equine sperm hyaluronidase was used to label fresh and capacitated stallion sperm, followed by indire...
Balasuriya UB, Snijder EJ, van Dinten LC, Heidner HW, Wilson WD, Hedges JF, Hullinger PJ, MacLachlan NJ.Virus derived from an infectious cDNA clone of equine arteritis virus (EAV030H) was intranasally inoculated into two stallions, neither of which subsequently developed clinical manifestations of equine viral arteritis (EVA). Virus was isolated from nasal swabs and mononuclear cells collected from both stallions
Parlevliet JM, Colenbrander B.In the selection procedure to acquire a breeding licence, 3-year-old Dutch Warmblood stallions have to undergo a breeding soundness test It is questioned whether this evaluation is predictive of the stallion's fertility results in the first breeding season. Therefore, semen parameters at the beginning of their first breeding season were evaluated and correlated to nonreturn at first cycle and foaling rate of mares bred by stallions (n = 13). The total number of mares inseminated with chilled semen from those stallions was 1055. Semen parameters were recorded on 2 ejaculates, collected 1 h apar...
Ellington JE, Samper JC, Jones AE, Oliver SA, Burnett KM, Wright RW.Formation of a spermatozoa ('sperm') reservoir in the mare is thought to occur through lectin-mediated sperm attachment to the oviductal epithelium. Once attached, prefertilization sperm survival is supported by oviductal factors. Cryopreservation of stallion sperm decreases the number of sperm attaching to oviduct epithelial cells (OEC) and the length of time these sperm survive. Quantification of in vitro interactions between sperm and OEC in a co-culture system may provide an assay for functional integrity of cryopreserved or fresh sperm samples. Additionally, superior additives for in vitr...
Patton JF, Balasuriya UB, Hedges JF, Schweidler TM, Hullinger PJ, MacLachlan NJ.An avirulent, novel variant of equine arteritis virus (EAV; CA95G) was isolated from the semen of a persistently infected Standardbred stallion. The CA95G virus caused subclinical infection and seroconversion in susceptible horses, and virus was isolated only once from blood and nasal secretions collected from 6 experimentally infected horses. Sequence analysis of genes encoding the known EAV structural proteins shows that this highly attenuated strain of EAV is genetically similar to virulent field strains of EAV and, in particular, to a strain of EAV that was isolated during an outbreak of e...
Starick E.A reverse transcription-polymerase chain reaction (RT-PCR) assay using four different primer pairs for the detection of equine arteritis virus (EAV) RNA in semen and tissue samples was evaluated. A fragment encoding the leader sequence of the EAV genome was most successfully amplified. The specificity and sensitivity of RT-PCR was assessed by virus isolation in cell culture, restriction analysis, dot blot hybridisation and nested PCR. To this end, 23 semen samples from seropositive stallions and 11 tissue samples from 4 aborted foals were tested. Compared to the virus isolation test in cell cu...
Lindeberg H, Kurtén A, Koskinen E, Katila T.The effect of addition of glycine betaine to a lactose-EDTA freezing medium on the post-thaw motility of stallion semen was determined. The first three semen-rich fractions of nine stallions were collected with an open-end Krakow artificial vagina on consecutive weekdays. Semen was frozen using the Hannover method with freezing media containing glycine betaine in various concentrations from 0 to 5%. After thawing, sperm motility was analysed both by a light microscope and by a Hamilton-Thorn Motility Analyser. Total and progressive post-thaw motilities of semen containing 0.25-3% glycine betai...
Hedges JF, Balasuriya UB, Timoney PJ, McCollum WH, MacLachlan NJ.The persistently infected carrier stallion is the critical natural reservoir of equine arteritis virus (EAV), as venereal infection of mares frequently occurs after breeding to such stallions. Two Thoroughbred stallions that were infected during the 1984 outbreak of equine viral arteritis in central Kentucky subsequently became long-term EAV carriers. EAV genomes amplified from the semen of these two stallions were compared by sequence analysis of the six 3' open reading frames (ORFs 2 through 7), which encode the four known structural proteins and two uncharacterized glycoproteins. The major ...
Ellington JE, Samper J, Jones A, Oliver SA, Burnett K, Wright RW.To compare function of cultured cryopreserved stallion spermatozoa in a modified Tyrode's medium (TM), with or without bovine serum albumin (BSA), or in uterine tube (oviduct) epithelial cell (OEC) coculture in TM, with or without BSA. Methods: Cryopreserved spermatozoa from 6 proven stallions and OEC from bovine reproductive tracts in follicular phase. Methods: Thawed spermatozoa were cultured in TM, with or without BSA, or cocultured with OEC monolayers in TM, with or without BSA. Percentages of capacitated and acrosome-reacted spermatozoa were measured at 5 hours for TM cultures. Spermatozo...
Klug E, Sieme H.The equine virus arteritis (EVA) consistently epidemically varying throughout the different breeds of the horse breeding countries is up to now only of lower significance by means of the typical clinical manifestation as well as an abortion causing factor. The susceptibility of the sexual mature stallions against the equine arteritis virus (EAV) causes different infection response which may lead to some restrictions in their use in natural breeding especially in the artificial insemination. In a certain not precisely predictable part of the stallion population EAV infection will cause a transi...
Bader H, Röhrsheim C, Koene M, Meinecke B.Investigations in different species including the horse have demonstrated that prostaglandin F2 alpha (PGF2 alpha) is involved in initiating uterine contractions occurring during mating and artificial insemination (A.I.). Uterine contractions play an important role with respect to the sperm transport within the female genital tract. The objective of the present investigation was to evaluate whether the administration of PGF2 alpha (Dinoprost) synchronously to A.I. could have a positive effect on the pregnancy rate in mares. A field study including 346 warmblood-mares (age two to 20 years) belo...
Minelli A, Moroni M, Martínez E, Mezzasoma I, Ronquist G.Equine seminal plasma was shown to contain membrane vesicles that are similar to the well characterized prostasomes in human seminal plasma. Determination of nucleoside and nucleotide concentrations of these particles have shown that ATP, ADP and adenosine are the main components of the nucleotidic pool. 5' nucleotidase, endopeptidase and dipeptidyl peptidase i.v. activities have been found on the surface of the particles. The interaction between these prostasome-like vesicles and spermatozoa was demonstrated by electron micrograph scans which revealed the steps of a fusion-like process leadin...
Starick E.Serum samples from 72 stallions were examined for the occurrence of antibodies against equine arteritis virus, of which 41 animals (57%) were found to be positive. 32 of the seropositive stallions were then screened for persistent EAV infection, before and after the breeding season. Semen samples were investigated by RT-PCR followed by dot blot hybridization and nested PCR, and by virus isolation on cell cultures as well. The carrier state was virologically confirmed in 11 of 32 stallions (34%) during the first and in 9 of 20 (45%) during the second investigation. RT-PCR followed by confirmato...
Schumacher J, Varner DD, Crabill MR, Blanchard TL.To evaluate the effect of a shunt created between the corpus cavernosum penis (CCP) and corpus spongiosum penis (CSP) on erectile and ejaculatory function of normal stallions and to verify persistence of the shunt. Methods: The capability of stallions to develop an erection and to ejaculate was evaluated before and after creation of a corporeal shunt. Persistence of the shunt was determined by dye injection into the CCP at necropsy. Methods: Six stallions. Methods: A CCP-CSP shunt was created in five stallions. Semen was collected before and 4 to 14 weeks after surgery, before the horses were ...
Fouchécourt S, Dacheux F, Dacheux JL.Microsequencing after two-dimensional electrophoresis revealed a major protein, glutathione-independent prostaglandin D2 synthase (PGDS) in the anterior epididymal region fluid of the ram and stallion. In this epididymal region, PGDS was a polymorphic compound with a molecular mass around 30 kDa and a range of pI from 4 to 7. PGDS represented 15% and 8% of the total luminal proteins present in this region in the ram and stallion, respectively. The secretion of the protein as judged by in vitro biosynthesis, and the presence of its mRNA as studied by Northern blot analysis, were limited to the ...
Love CC, Kenney RM.A variety of testicular insults can induce changes in the structure of spermatozoal chromatin, resulting in spermatozoal DNA that is more susceptible to acid-induced denaturation. The degree of change in the DNA can be measured using the sperm chromatin structure assay (SCSA). The SCSA measures the relative amounts of single- and double-stranded DNA after staining with the metachromatic dye, acridine orange. Here we used a stallion model (n = 4) to study the effects of scrotal heat stress on spermatozoal DNA. This model was created by insulating stallion testes for 48 h and collecting sperm da...
Feh C.A study of a herd of Camargue horses Equus caballus, showed that while the majority of high-ranking stallions held single-male harems, some sons of low-ranking mares, being low ranking themselves, formed alliances that could last a lifetime. The two stallions were each other's closest associate and preferential grooming partner. Alliances were based on coalitions in which either both partners confronted an intruder synchronously or the dominant of the pair tended the female(s) while the subordinate simultaneously displayed towards the rival. Alliance partners were of similar age but were not m...
Guignot F, Ottogalli M, Yvon JM, Magistrini M.The objective of this study was to perform intracytoplasmic sperm injection (ICSI) on in vitro matured equine oocytes and to improve in vitro embryonic development on Vero cells after activation of the microinjected oocytes with calcium ionophore. After maturation (23 or 40 h, 38.5 degrees C, 5% CO2), the cumulus-oocyte complexes were denuded, centrifuged and all oocytes exhibiting the first polar body were microinjected. ICSI was performed using fresh semen from three fertile stallions. Microinjected oocytes were activated with calcium ionophore A23187 (10 min, 10 microM) and cultured individ...
Hassel DM, Langer DL, Snyder JR, Drake CM, Goodell ML, Wyle A.To identify breed, age, sex, physical findings, history, and outcome of treatment in horses and other equids with enterolithiasis. Methods: Retrospective study. Methods: 900 equids with enterolithiasis. Methods: Medical records from equids with enterolithiasis admitted between 1973 and 1996 were reviewed. Data on signalment, history, physical examination and clinicopathologic findings, surgical findings, and outcome were compiled from records and from telephone interviews with owners. Sex and breed predilections were determined by comparison of the study population with the general hospital po...
Brinsko SP.Genital neoplasms in the male horse are relatively uncommon. Squamous cell carcinomas and squamous papillomas are the most commonly diagnosed neoplasms of the penis and prepuce. Geldings appear to be overrepresented for these types of neoplasms, and accumulation of smegma may be a contributing factor. Early diagnosis and treatment are essential for salvaging these organs before lesions become excessively large and invasive or are allowed to metastasize. Newer treatment modalities such as 5-fluorouracil appear to be promising alternatives to surgical excision. Although generally considered to b...
Blunden AS, Smith KC, Whitwell KE, Dunn KA.A severe multi-systemic form of equid herpesvirus-1 infection is described in an adult zebra stallion. There was multifocal necrotizing rhinitis, marked hydrothorax and pulmonary oedema, with viral antigen expression in degenerating epithelial cells, local endothelial cells and intravascular leucocytes of the nasal mucosa and lung. Specific localization of EHV-1 infection was seen in the testes and epididymides, including infection of Leydig cells and germinal epithelium, which would have facilitated venereal shedding of virus in life. The case provided a unique opportunity to study hitherto u...
Hoshiba H, Sinowatz F.Spermadhesins are proteins with various functions in sperm capacitation and zona pellucida binding. In this study the cellular localization of the spermadhesin AWN-1 has been examined in the equine male genital tract. Results obtained by immunohistochemical methods reveal that in the horse AWN-1 is synthesized in spermatogonia, in the rete testis, the ductus epididymidis and the seminal vesicles. These findings indicate that the cellular origin of spermadhesins is species-specific.
Bergeron JA, Hendrickson DA, McCue PM.A 25-month-old castrated horse was admitted for evaluation of stallion-like behavior. Twelve months earlier, bilateral cryptorchidism had been diagnosed, and the horse underwent a laparoscopic castration. At that time, the left testis was removed from the abdominal cavity, but the right testis, which was located in the inguinal ring, was left in place to undergo avascular necrosis after laparoscopic cauterization and transection of the testicular vasculature. On physical examination, an apparently clinically normal right testis was palpated within the scrotum. Administration of human chorionic...
Eterpi M, Magistrini M, Couty I, Gavin-Plagne L, Aguirre-Lavin T, Schmitt E, Carion O.Among biotechnologies of reproduction in the equine species, artificial insemination remains the most used technology especially for cooled transported sperm. Although the use of INRA96 extender has demonstrated its efficiency for long-term sperm storage at 4°C or 15°C, some stallions ("bad coolers") are excluded from such technology. Some years ago, we demonstrated that liposomes produced from egg yolk (EY) phospholipids could be an alternative to egg yolk plasma in stallion freezing extenders. To develop a new extender for sperm chilling, we evaluated the protective effect of liposomes pr...
Brito LF, Kelleman A, Greene LM, Raz T, Barth AD.A 5-year-old Arabian stallion was managed for breeding with fresh/extended semen during a period of 8 months with a resulting per cycle pregnancy rate of 26.3%. The stallion was in good health and no abnormalities of the reproductive tract were observed. Evaluation of several ejaculates revealed that sperm production and semen quality were mostly unchanged during the period of evaluation, that sperm production was normal and that semen quality was extremely poor. The most prevalent sperm defects were abnormal heads and mid-pieces. Most abnormal heads were microcephalic and/or tapered and consi...
Guan F, Uboh CE, Soma LR, You Y, Li X, McDonnell S.19-Norandrostenedione (NAED) and nandrolone are anabolic-androgenic steroids (AASs). Nandrolone was regarded solely as a synthetic AAS until the 1980s when trace concentrations of apparently endogenous nandrolone were detected in urine samples obtained from intact male horses (stallions). Since then, its endogenous origin has been reported in boars and bulls; endogenous NAED and nandrolone have been identified in plasma and urine samples collected from stallions. More recently, however, it was suggested that NAED and nandrolone detected in urine samples from stallions are primarily artifacts d...
Hatazoe T, Kawaguchi H, Hobo S, Misumi K.Equine pituitary pars intermedia dysfunction (PPID) generally occurs in older horses showing hirsutism, delayed molting, weight loss, polydipsia, polyuria, laminitis, and reproductive disorders (in broodmares), but there have been no reports on stallions. This report presents a case of a 21-year-old Thoroughbred stallion that developed hirsutism and experienced delayed molting. There were no abnormal findings for semen quality or the stallion's sexual desire. The horse was diagnosed with PPID based on dexamethasone suppression test and plasma levels of adrenocorticotropic hormone. It was then ...
Han H, Wang A, Liu L, Zhao G, Su J, Wang B, Li Y, Zhang J, Wu B, Sun W, Hu S, Li S, Zhao L, Li X.Most hinnies (female donkey×male horse) and mules (female horse×male donkey) are sterile with few reports of equine fertile hybrids. The main cause of this sterility is thought to be a meiotic block to spermatogenesis and oogenesis. This study compared the developmental features of the testes and a histological analyses of spermatogenesis in a male hinny with those of a normal, fertile stallion and Jack donkey. Hinny testes showed a thicker tunica albuginea, fewer blood vessels and more connective tissue in the testis parenchyma than those of the stallion and Jack donkey. Although the mean n...
Little TV, Woods GL.The accessory sex glands of 10 stallions were examined by transrectal ultrasonography. Seminal vesicles were 26.4 +/- 5.2 (s.d.) mm in width and 9.2 +/- 3.1 mm in height. Ampullae were 16.3 +/- 3.6 mm in width and 12.9 +/- 3.9 mm in height. Bulbourethral glands were 19.7 +/- 4.6 mm in width and 32.4 +/- 6.7 mm in length. Prostate lobes exceeded 34 mm in width and were 23.5 +/- 5.7 mm in height. The prostatic isthmus was 6.0 +/- 1.4 mm in height. The seminal colliculus, masculine uterus, and deferent ducts were also identified and characterized. Five of these stallions were killed to compare tr...
Miller LMJ, Woodward EM, Campos JR, Squires EL, Troedsson MHT.Sperm protein at 22 kDa has been associated with fertility. Objective: The objectives of this study were to determine (1) the localization pattern of SP22 on ejaculated and caudal epididymal equine spermatozoa and in epididymal fluid, and to (2) characterize SP22 protein and mRNA expression in testicular and epididymal tissues in response to heat-induced testicular degeneration. Methods: Semen was collected before and after hemi-castration, as well as prior to and following insulation of the remaining testes, and tissue specimens were collected for analysis. Results: Histopathology confirmed ...
Salem SE, Sinnott A, Roach JM, Verheyen KLP, de Mestre AM.Multiple pregnancies (MPs) are commonly diagnosed during breeding management of mares. Whilst some studies have reported on factors associated with the risk of MPs, few have utilised multivariable data analysis to control for confounding variables. A prospective cohort study of Thoroughbred broodmares was conducted with information collected on 27 factors. Mixed-effects logistic regression was used to determine risk factors for MPs. Mare, stallion, stud, and veterinarian were evaluated as random effects. The prevalence of MPs in 1754 mares and 2245 pregnancies was 16.06% (95% confidence interv...
Parker NA, Bailey TL, Bowen JM, Ley WB, Purswell BJ, Dascanio JJ.Like the human female, the mare experiences reproductive tract pathology that may sometimes be circumvented by the use of assisted reproductive technologies (ARTs). One such technology, gamete intrafallopian transfer (GIFT), may be used in mares that exhibit ovulatory, oviductal, or uterine abnormalities that limit the use of common ARTs, such as embryo transfer. Homologous GIFT has been successfully performed in the horse; however, the logistics, costs, and associated risks of surgically transferring gametes to the oviducts of a recipient mare are considerably high. Use of a less costly speci...
Turner RM, Love CC, McDonnell SM, Sweeney RW, Twitchell ED, Habecker PL, Reilly LK, Pozor MA, Kenney RM.An 8-year-old stallion was evaluated because of recurrent urinary tract infections and chronic intermittent urospermia. After extensive diagnostic testing, it was hypothesized that the stallion had a reflex dyssynergia of the bladder and urethral sphincter. Initial attempts to manage the urospermia included semen fractionation, semen collection after voluntary urination, and use of semen extenders. None of these efforts reliably yielded a quality ejaculate. Administration of imipramine hydrochloride (1.2 mg/kg of body weight, PO, 4 hours prior to semen collection) was initiated in an attempt t...
Noschka E, Werre SR, Crisman MV, Thatcher CD, Milne GL, Dahlgren LA.F2-isoprostanes have been used extensively to quantify lipid peroxidation in association with risk factors in various diseases. Horses with colic may have intestinal ischaemia and/or inflammation characterised by oxidative stress and increased production of isoprostanes. Objective: To gather preliminary data regarding the feasibility of using urine F2-isoprostanes and isoprostane metabolites as early screening tools for the presence of gastrointestinal disease requiring surgical intervention in horses and ultimately develop a stall-side test capable of identifying these horses as early as poss...
Hyland JH, Bristol F.Oestrus was synchronized in 116 mares by means of an i.m. injection of prostaglandin F-2 alpha (Day 0) and of fluprostenol (a PG analogue) on Day 16. Mares were then randomly divided into three groups. Group A mares (N = 30) were given 2500 i.u. hCG I.M. ON Day 20 and artificially inseminated on Day 21 without detection of oestrus. Group B mares (N = 32) were given 2500 i.u. hCG i.m. on Day 20 and inseminated on Days 21 and 23, also without oestrus detection. Group C mares (N = 54) were teased on Days 18, 19, 21, 23 and 25 and inseminated on Days 19, 21, 23 and 25 while they were in oestrus. S...
Medeiros BR, Garbade P, Seixas L, Peripolli V, McManus C.The aim of this study was to evaluate genetic parameters for subjective scores given at the Brazilian Sport Horse (BSH) Stallion Approval by estimating heritability (h) for morphological, gait, and jumping traits and genetic correlations (γ) among the functional ones and by verifying selection feasibility. The analysis included 1179 complete evaluations from 294 horses, by 4.26 ± 0.96 judges. Each trait was evaluated using mixed models in SAS® v9.2, considering the individual as a random effect. Variance components and genetic parameters were obtained by single and two-trait animal mode...
Silva DM, Holden SA, Lyons A, Souza JC, Fair S.The aim of the present study was to assess the effect of the addition of docosahexaenoic acid (DHA) on the in vitro quality of cooled and frozen-thawed stallion semen. In Experiment 1, semen from 10 stallions was collected (three ejaculates per stallion). Semen was diluted to 100×106 spermatozoa mL-1 with 0.02mM vitamin E (VE) and 0, 1, 10 or 20ng mL-1 DHA and frozen. Semen was thawed and total motility (TM), rapid progressive motility (PM), acrosome integrity, membrane fluidity and morphology were assessed. In Experiment 2, semen from three stallions was collected (three ejaculates per stall...
Ginther OJ, Lara A, Leoni M, Bergfelt DR.Four herds of pony mares, each consisting of a stallion and six mares, were used to characterize the nature of herding by the stallion and the factors that induced the herding behavior. Herding behaviors were compared among four successive treatments (six mares alone, stallion added, two new mares added, and entire herd moved to a new pasture). A new treatment was initiated every 7 days and behavior was studied for 5 consecutive days (Days 1-5) for each treatment. Observations were made every 10 min during a 2-h period for each day. The extent of herding was quantitated by the mean distances b...
Senra RL, Ramírez-López CJ, Magalhães-Júnior MJ, Neves JGDS, Barros E, Waddington B, Guimarães SEF, Guimarães JD, Baracat-Pereira MC.Horses are seasonal polyoestrous animals, and the photoperiod is the main factor modulating their reproductive activity. There is no consensus on the andrological and biochemical factors that influence breeding seasonality. To assess the involvement of climate in reproduction, Mangalarga Marchador stallions were monitored over 1 year regarding semen quality and seminal plasma proteome. Here, we show that kallikrein (KLKs) proteoforms in seminal plasma are involved in climate conditioning of reproduction. During the breeding season, greater abundance and different types of KLKs occurred simult...
Morris LH, Allen WR.The need for relatively high numbers of spermatozoa for artificial insemination limits our application of recently available technologies such as sex-sorted semen. The fertility of two different methods of low dose insemination using fresh, frozen and sex-sorted semen are compared in this overview. Satisfactory conception rates are described using very low doses of spermatozoa inseminated by either hysteroscopic or deep uterine insemination methods, proving the stallion is fully fertile. The hysteroscopic method appears to give higher conception rates when inseminating fewer than 5 x 10(6) spe...
Roser JF, Tarleton M, Belanger JM.Recent studies in our laboratory investigating plasma gonadotrophin concentrations before and after castration indicate that the hypothalamic-pituitary axis is not the original site of dysfunction in stallions with idiopathic infertility. In the present study, fertile, subfertile and infertile stallions were subjected to replacement therapy with oestradiol and testosterone 1 year after castration to investigate hypothalamic-pituitary axis function further. Fertile (n=5), subfertile (n=3) and infertile (n=2) castrated stallions of Light horse breeds, aged 11-23 years, were given either oestradi...
Aurich C, Sieme H, Hoppe H, Schlote S.To investigate the involvement of endogenous opioids in the regulation of gonadotrophin release in male horses, effects of the opioid antagonist naloxone (0.5 mg kg-1 i.v.) on plasma LH and testosterone concentrations and the possible influence of season and of gonadal steroids were investigated. To determine quantitative as well as qualitative changes in gonadotrophin release, LH concentrations were measured by radioimmunoassay and by an in vitro bioassay. Experiments were performed in May, August and December. In stallions, basal LH secretion in May and August was significantly higher than i...
Jönsson L, Näsholm A, Roepstorff L, Egenvall A, Dalin G, Philipsson J.Soundness is important for welfare and utility of the riding horse. Musculoskeletal disorders are the most common causes of interruption in training and of culling. Despite great importance, heritability of a majority of health traits in horses has previously not been estimated. The objective was to perform genetic analyses of medical and orthopaedic health traits in young riding horses, including estimates of heritability and genetic correlations between health traits, and to reveal possibilities for genetic evaluation of stallions for progeny health. Results: The heritability of health trait...
Glaser AL, de Vries AA, Rottier PJ, Horzinek MC, Colenbrander B.Sero-epidemiological surveys have revealed that equine arteritis virus (EAV) is prevalent in most European countries. The virus causes sporadic cases of respiratory disease and abortion in horses, the incidence of which has increased in recent years. Mares and geldings eliminate virus after acute infection, but 30% to 60% of stallions become persistently infected. In these animals, EAV is maintained within the reproductive tract and is shed continuously in the semen. Persistent infection with EAV in stallions has no negative consequences for fertility but mares inseminated with virus-contamina...
Pruß D, Oldenhof H, Wolkers WF, Sieme H.The aim of this study was to establish an alginate encapsulation procedure for stallion sperm, and investigate if sperm encapsulation enhances longevity during cold storage and survival after cryopreservation. First, biocompatibility of the compounds needed for encapsulation was tested and factors determining capsule structure were identified. Sperm encapsulation was realized either by depositing droplets (20 µL) of sperm solution supplemented with barium or calcium chloride (10 mM) in alginate solution (0.25%, w/v), or by adding sperm-alginate droplets in solution containing barium or calc...
McDonnell SM, Love CC, Martin BB, Reef VB, Kenney RM.Two mature breeding stallions were evaluated because of specific ejaculatory dysfunction, and each was found to have aortic-iliac thrombosis occluding 60 to 70% of the aortic lumen. In each case, the stallion had strong libido, normal mounting, and vigorous initial thrusting. With continued exertion, thrusting became weak and dismount was awkward. Treatment aimed at maximizing sexual arousal before mounting and reducing hind limb pain and exertion during breeding allowed these stallions to continue breeding. A program of gradually increasing daily exercise also was associated with improved bre...
McDonnell SM, Oristaglio Turner RM.Imipramine-induced ex copula ejaculates (11) and fractionated in copula ejaculates were collected from each of 5 pony stallions for freezing in 5-ml straws (6), using a modified Kenney glucose skim-milk extender (2). Initial post-thaw total and progressive motilities and daily post-thaw total and progressive motilities, as well as the number of days to reach 0 progressively motile spermatozoa, were also similar for the 2 methods of collection. The percentage of morphologically normal spermatozoa both before freezing and after thawing were also similar for in copula and ex copula ejaculates. Co...
Freitas ML, Viana JHM, Dode MAN, Maggiotto SR, Pivato I, Braga TRC, Lim AIPG, de Oliveira RA.The effects of seasonality on the reproduction of stallions vary based on the latitude. Although previous studies have shown the influence of seasonality in raw semen quality in south-eastern Brazil, data regarding the influence of seasonality in cooled and frozen stored semen in Brazil is limited. Therefore, in this study, we have analysed if seasonality influences the hormone production (i.e., cortisol and testosterone), spermatogenesis, and quality of fresh, cooled, and frozen semen of stallions in central Brazil, and established the season most suitable for semen cryopreservation in a lati...
Gibb Z, Grupen CG, Maxwell WM, Morris LH.The fertility of sex-sorted, cryopreserved stallion sperm must be improved for the sex-sorting technology to be applied commercially. Objective: To optimise the conditions used to liquid store stallion sperm prior to sex-sorting and assess the fertility of sperm following sex-sorting and cryopreservation. Methods: Both in vitro experiment and randomised controlled trial in healthy, client-owned mares. Methods: Stallion ejaculates (n = 9) were diluted in either a skimmed milk (KMT) or BSA (I-BSA) based media to 25 × 106 sperm/ml directly (+SP25) or washed to remove seminal plasma and diluted t...
Mittelholzer C, Johansson I, Olsson AK, Ronéus M, Klingeborn B, Belák S.Recovery of infectious Equine arteritis virus (EAV) from the semen of persistently infected Swedish stallions was attempted by classical cell culture isolation and by transfection of extracted total RNA. Whereas virus from semen samples stored for several months at -20 degrees C or from extended semen could only be recovered by transfection of extracted RNA, isolation in cell culture was achieved readily with fresh, unextended semen stored at -70 degrees C or directly used after sampling. In parallel, the viruses were examined in the variable region of the large glycoprotein GP5 by nested RT-P...
Okólski A, Babusik P, Tischner M, Lietz W.Comparisons were made between 2 methods of oocyte recovery from the ovarian follicles of slaughtered mares: 500 oocytes (3 per mare) were obtained by aspiration of follicular fluid from ovaries of 162 mares, and 120 oocytes (8 per mare) by isolation and rupture of follicles from ovaries of 14 mares. In the oocytes recovered after rupture of follicles, 89.2% were morphologically unchanged, in comparison to 29.3% obtained by aspiration of follicular fluid. Stallion spermatozoa capacitated in vitro were tested on zona-free hamster oocytes. The stallion spermatozoa were washed in TCM-199 and prein...
Leme DP, Papa FO, Roser JF.The objective of this study was to investigate reproductive characteristics of stallions at a tropical zone in the breeding and non-breeding seasons. The following parameters were assessed: testicular volume; semen quality; and serum concentrations of LH, FSH, and testosterone; in addition to the percentages of germ cells and proportions of germ cells/Sertoli cells by testicular cytology in stallions. Semen was collected from eight adult stallions twice a week during a 12-week period in both seasons (6 weeks before and 6 weeks after the summer and winter solstices). Jugular blood samples were ...
Lançoni R, Celeghini ECC, Gonella-Diaza AM, Júnior VG, de Carvalho CPT, Zoca GB, Garcia-Oliveros LN, Batissaco L, Oliveira LZ, de Arruda RP.This study aimed to assess the semen ubiquitin levels of stallions with good (GF) and poor semen freezability (PF) and to evaluate the relationship between sperm ubiquitination and sperm morphological defects. Five ejaculates from eight adult stallions (n = 40) were collected and cryopreserved. Then, the ubiquitin level in equine sperm cells was assessed by immunohistochemistry with epifluorescence microscopy, and sperm morphology was assessed by differential interference contrast microscopy. Sperm cells were classified according to the intensity (classification 1: from I to IV; I = very l...
