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.
Roser JF, Hughes JP.Hormonal effects of prolonged administration of gonadotrophin-releasing hormone (GnRH) were investigated in 7 fertile stallions in winter and summer. The stallions were divided into 4 groups so that 1 animal received 0.625 micrograms of GnRH and each of 2 animals received 1.25, 2.5 or 5.0 micrograms of GnRH subcutaneously every 30 min for 5 days. Daily blood samples were collected from 5 days before to 5 days after treatment for measurement of plasma concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone (T) and oestrogen conjugates (EC). Five-minute blood...
Kindahl H, Daels P, Odensvik K, Daunt D, Fredricksson G, Stabenfeldt G, Hughes JP.Three different routes of administering Salmonella typhimurium endotoxin to mimic naturally occurring endotoxaemia were tried in the mare. Bolus injection, repeated bolus injections and continuous low-dose infusion were compared with prostaglandin F2 alpha release, leucocyte count and clinical response. A biphasic prostaglandin release and a pronounced leucopenia of almost identical patterns were seen in all models. Repeated bolus injections showed that the second injection initiated only a small prostaglandin release indicating the development of refractoriness to the treatment. A similar ref...
Guillaume D, Palmer E.Two experiments tested the hypothesis that exogenous melatonin (12 mg) given 4 h before dusk (evening melatonin), or near dawn (morning melatonin), would mimic a prolongation of the night and suppress stimulation of the ovaries induced by long days. Experiment 1 consisted of a non-stimulated control group, a control group stimulated by 14.5 h of light, a treated group stimulated with 14.5 h of light plus evening melatonin, a control group given 17.5 h of light and a treatment group given 17.5 h of light plus morning melatonin. The mean (+/- s.e.m.) intervals from the start of treatment to the ...
Argo CM, Cox JE, Gray JL.This study tested the role of melatonin in the regulation of seasonal physiological change in the pony stallion. Four 3-year-old, Welsh Mountain pony stallions were housed initially under the prevailing short-day photoperiod in December (8 of light [L]:16 h of darkness [D]) before being transferred to long days (16L:8D) on 13 January for the remaining 22 weeks of the study. On Day 76 (11 weeks later) the stallions began an 11-week period of daily melatonin treatment (20 mg orally, 8 h after lights on). Marked changes in mean plasma testosterone, beta-endorphin and cortisol concentrations occur...
McFarlane JR, Cabrera CM, Coulson SA, Papkoff H.The rhinoceros is an endangered species related to the horse family. Little is known of its reproductive endocrinology. The objectives of this study were to partially purify rhinoceros pituitary hormones, determine which assays could be used for their assessment, and to ascertain whether rhinoceros LH possesses the intrinsic FSH activity of equine LH. A single pituitary each from a White (1.3 g) and a Black (1.2 g) Rhinoceros was homogenized and extracted (pH 9.5), then subjected to pH and salt fractionation, and ion-exchange chromatography (DEAE and Sephadex SP-C50) to yield partially purifie...
Pantke P, Hyland J, Galloway DB, MacLean AA, Hoppen HO.Equine plasma luteinizing hormone (LH) possesses both biological (in vitro bioassay, B) and immunological (radioimmunoassay, I) activities and the ratio of B:I varies with stage of the oestrous cycle. To estimate the contribution made by pituitary secretion and peripheral metabolism to changes in the B:I ratio, pituitary venous effluent and circulating plasma from 5 dioestrous and 2 oestrous mares were analyzed using both an in vitro bioassay and a radioimmunoassay. During dioestrus, LH was released in a pulsatile fashion with a frequency of 1.4 pulses/24 h and a pulse duration of 20-40 min (c...
Henry M, McDonnell SM, Lodi LD, Gastal EL.The mating behaviour of 2 jacks, each with 21 non-pregnant jennies, was studied when the jennies were in natural oestrus and simultaneously induced oestrus. The main observations were: efficient pasture breeding at natural and induced oestrus, a territorial sociosexual structure, prolonged pre-copulatory interaction, gradual increase of mating activity up to 2 days before ovulation, a copulatory sequence similar to that of horses, vocalization of the jack as a conspicuous behaviour initiating pre-copulatory interaction, frequent heterotypical behaviour of jennies and active involvement of jenn...
Flisińska-Bojanowska A, Komosa M, Gill J.1. The diurnal changes in the glucose level and in activity of FDPA, A1AT and AspAT in four pregnant standard-bred mares were studied. 2. As a control four barren mares, were kept and examined in the same conditions. 3. Blood samples were taken every 4 hr for one day, each month, throughout pregnancy, or one year. 4. A diurnal rhythm in activity of A1AT and AspAT in barren mares was found. The pregnancy masked diurnal rhythm in activities of both transaminases. 5. No diurnal rhythm in glucose level and FDPA activity in both groups of mares was observed. 6. Seasonal cyclicity was found in all i...
Fayrer-Hosken RA, Caudle AB, Shur BD.beta 1, 4-Galactosyltransferase (GalTase) is localized to the plasma membrane of mouse sperm, in which it mediates the binding of sperm to glycoconjugate residues in the egg zona pellucida. In this study, the presence of subcellular distribution of sperm GalTase were determined in two other mammalian species that yield sufficient sperm for subcellular fractionation. Equine and bovine semen were collected, and the plasma membranes (PM), outer acrosomal membranes (OAM), and inner acrosomal membranes (IAM) were sequentially removed. The purities of the isolated membrane preparations were determin...
Watkins JP, Taylor TS, Day WC, Varner DD, Schumacher J, Baird AN, Welch RD.From 1980 to 1989, 8 cesarean sections were performed on an elective basis in 5 mares. Four mares had partially obstructed pelvic canals; 2 of these mares had previously lost foals because of dystocia. Cervical adhesions that might obstruct passage of the fetus through the pelvic canal was suspected in the fifth mare. Cesarean section was performed prior to mares entering the first stage of labor. Readiness for birth was estimated by development of the mare's mammary gland and the presence of colostrum in the udder. A ventral midline celiotomy provided excellent exposure and healed without com...
Pycock JF, Allen WE.Exudate and uterine flushings were collected at either 30, 60, 120 or 240 mins after intrauterine infusions of Streptococcus zooepidemicus in genitally normal mares during oestrus. Uteri were also flushed without prior induction of endometritis. Protein concentrations in exudate and flushings increased with time and exudate pH decreased with time; the pH of flushings did not alter. Lysozyme and lactate dehydrogenase were present in flushings from non-infected uteri, but concentrations increased with time after infection. Immunoreactive prostaglandin E2 was undetectable before infection, but co...
Woods J, Bergfelt DR, Ginther OJ.The effects of pre-ovulatory and post ovulatory insemination on pregnancy rate and embryonic-loss rate were studied in 268 mares in two experiments. Within each experiment mares were randomised within replicates as follows: to be inseminated on the day the pre-ovulatory follicle reached 35 mm (pre-ovulatory group), to be inseminated on the day of ovulation (Day 0 group), and to be inseminated on the day after ovulation (Day 1 group). Ultrasonic pregnancy diagnoses were performed on Days 11, 12, 13 and 14 (Experiment 1) and Days 11, 12, 13, 14, 15, 20 and 40 (Experiment 2). Combined for the two...
Sirois J, Kimmich TL, Fortune JE.Ovulation in mares is preceded by a long and variable estrous period. The differentiation of equine preovulatory follicles with respect to steroidogenic capacity and responsiveness to equine gonadotropins was studied by culturing pieces of follicle wall (FW = theca + attached granulosa cells) from preovulatory follicles isolated during late diestrus (day 14 of cycle, n = 5 mares), early estrus (1st-2nd day of estrus, n = 6) or late estrus (4th or 5th day of estrus, n = 6). FW was cultured with or without equine LH, FSH, LH + FSH, or CG (10 or 100 ng/ml) and medium was collected and replaced at...
Doreau M, Boulot S, Barlet JP, Patureau-Mirand P.The yields and composition of milk from nursing mares were studied during the first two months of lactation in 11 mares of heavy breeds (784 kg). Daily yield increased from 21.7 to 24.6 kg between weeks 1 and 8 of lactation. Fat, protein, gross energy and Ca concentrations significantly decreased when lactose content increased during this period. Individual variations were higher for yield than for composition. Casein, whey protein and non-protein N (56, 34 and 10% of crude protein, respectively) and amino acid composition did not vary between weeks 1 and 8 of lactation.
Hinrichs K, Watson ED, Kenney RM.A functional corpus luteum was found in the ovary contralateral to the ovary with a granulosa cell tumor in a 24-year-old Standardbred mare. The mare was ovariectomized because she was to be used as a jump mare for collection of semen from stallions. The blood concentration of progesterone was 2.2 ng/ml, and the luteal tissue progesterone concentration was 6.3 micrograms/mg. Atrophy of the contralateral ovary is one of the major signs used in diagnosis of granulosa cell tumor; however, our findings indicate that the ovary contralateral to a granulosa cell tumor is not invariably nonfunctional....
Spier SJ, Carlson GP, Holliday TA, Cardinet GH, Pickar JG.Eleven horses (3 mares, 7 stallions, 1 gelding) with clinical and biochemical evidence of hyperkalemic periodic paralysis were studied. Each horse had history of episodic weakness, muscular tremors, or collapse, which lasted for periods of a few minutes to hours. Diagnosis was based on hyperkalemia in association with a spontaneous episode of paralysis or by precipitation of an episode by oral administration of potassium chloride. Clinical and biochemical events were documented during spontaneous and induced episodes of muscular weakness. During episodes, electrocardiographic findings were con...
Bowling AT, Millon LV.The phenotypic effects in a yearling Arab filly of a newly described equine autosomal trisomy syndrome for chromosome 30 (65,XX,+30) consisted of small size and severe angular deviation of front legs accompanied by mild polydactyly, but no mental dullness. This case was associated with advanced maternal age. Additional banding studies of a second trisomy case confirmed the assignment to chromosome 26 (64,XX,-26,+t(26q26q)) and evidence of her fertility was presented.
Hinrichs K, Schmidt AL, Memon MA, Selgrath JP, Ebert KM.Embryos were recovered from the uteri of mares 5 d after ovulation. Six embryos, all morulae, were placed singly in 200-ul droplets of Ham's F-12 with 10% fetal calf serum and cultured at 37 degrees C in a 5% CO(2) atmosphere. The embryos expanded to form blastocysts by the third day of culture. The blastocysts hatched from their zona pellucida, rather than the zona thinning and flaking off, as occurs in vivo. Hatching from the zona pellucida began on the third day of culture and was complete in five of six embryos by the sixth day. The embryonic capsule, normally present in equine embryos aft...
Zhang J, Boyle MS, Smith CA, Moore HD.The acrosome of the stallion spermatozoon was visualized by indirect immunofluorescence with monoclonal antibody (18.6) which recognized an integral acrosomal membrane component. Localization was confirmed by electron microscopy using peroxidase labelled antibody. In fresh semen samples (n = 19), 73.9 +/- 9.1% of the spermatozoa from five fertile stallions displayed a uniform bright fluorescence over their acrosome region. In two semen samples from an infertile stallion only 28% and 35% of spermatozoa showed the same pattern of fluorescence. Spermatozoa from fertile stallions incubated for up ...
Oikawa M, Yoshihara T, Kaneko M, Yoshikawa T.The morphology of the equine allantochorion at the tip of the pregnant horn was studied in the membranes of 14 mares. The findings in the allantochorion at the tip of the pregnant horn were of two types; one was growth retardation (hypoplastic villi, tunica adventitia of the vessels resembling embryonal connective tissue and the extended spaces of remnants of the extraembryonic coelom), the other was placental hypoxia or ischaemia (parakeratosis, stratified squamous metaplasia, necrosis of the trophoblasts, thickening of the basement membrane and fibrous hyperplasia of villous stroma). It seem...
Fenstermaker RA, Farmerie TA, Clay CM, Hamernik DL, Nilson JH.Expression of the glycoprotein hormone alpha-subunit gene occurs in the pituitaries of all mammals and in the placentas of primates and horses. In humans, tandem cAMP response elements (CREs), located in the proximal promoter-regulatory region of the alpha-subunit gene, act together with an adjacent upstream regulatory element to confer placenta-specific expression. Here, we report that the alpha-subunit genes of Old World Monkeys contain a single functional CRE. This suggests that tandem CREs are unique to higher primates and humans and are not absolutely required for placenta-specific expres...
Hyland JH, Langsford DA.Foetal death was induced in 10 Standardbred mares at day 45 of gestation by injecting 20 to 45 ml of hypertonic (24% W/V) saline into the conceptus at surgery. Ten mares underwent sham treatment and acted as controls. Blood and urine samples were collected every other day between days 30 and 45 post ovulation and at 0, 3 and 6 h relative to the infusion of saline in the treated mares, or sham treatment in control mares. Blood and urine samples were then collected daily between days 46 and 55 post ovulation. Urine oestrone sulphate (E1S) concentrations, measured by radioimmunoassay, increased b...
Martinuk SD, Bristol F, Murphy BD.Breeding trials were designed to determine the influence of the mare on serum concentrations of equine chorionic gonadotropin (eCG) from Day 39 to Day 104 of gestation. Sires were ranked according to mean eCG concentrations found in the groups of randomly selected mares to which they were mated in 1983. Mares were ranked according to their mean eCG concentrations on Days 55, 71 and 85 of gestation (Day 0 = mating), in 1983 and 1985. In the 1986 breeding season, mares that had pregnancies characterized by high eCG levels were mated to sires previously associated with low eCG concentration pregn...
Rabb MH, Thompson DL, Barry BE, Colborn DR, Hehnke KE, Garza F.Six pony geldings were actively immunized against GnRH conjugated to bovine serum albumin (BSA) to study 1) the relative dependency of LH and FSH storage, secretion and response to GnRH analog on GnRH bioavailability and 2) the effects of reduced GnRH bioavailability on GnRH storage in the hypothalamus. Five geldings were immunized against BSA. Geldings were immunized in December and 4, 8, 14, 20, 26 and 32 wk later. Ponies immunized against GnRH had increased (P less than .01) GnRH binding in plasma within 6 wk. By June, plasma concentrations of LH and FSH in ponies immunized against GnRH had...
Meinecke B, Gips H.The aim of the present investigations was to characterize the endocrine changes in the peripheral plasma during the periparturient phase of mares with a known history of obstetrical disorders. Blood plasma samples from 9 mares (8 mares during parturition, 1 mare during abortion) were collected and the following steroid hormones were radioimmunologically determined: progesterone (P4), dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEA-S), estrone (E1), estrone sulfate (E1-S), estradiol-17 beta (E2), estriol (E3), cortisol and transcortin. In general, with the exception of corti...
Ginther OJ.Individual follicles were monitored by ultrasonography in 15 mares during the transitional period preceding the first ovulation of the year and in 9 mares during the first interovulatory interval. During the transitional period, 7 mares developed 1-3 anovulatory follicular waves characterized by a dominant follicle (maximum diameter greater than or equal to 38 mm) that had growing, static, and regressing phases. The emergence of a subsequent wave (anovulatory or ovulatory) did not occur until the dominant follicle of the previous wave was in the static phase. After the emergence of the subsequ...
Cahill CM, Van der Kolk H, Goode JA, Hayden TJ.Highly purified and well-characterised preparations of equine prolactin and growth hormone from equine pituitary glands were employed to set up highly sensitive and specific homologous radioimmunoassays (RIA) for the measurement of hormone in horse plasma. The limit of sensitivity of the GH RIA was 1.2 ng/ml with mean intra- and inter-assay coefficients of variation (CV) of 6.6 and 10%, respectively. The sensitivity of the equine prolactin (ePRL) RIA was 0.5 ng/ml with mean intra and inter-assay CV of 9.1 and 15.6%, respectively. Dose-response curves of a crude pituitary gland extract and plas...
Sampaio BFB, Nogueira BG, Souza MIL, Silva EVDCE, Zúccari CESN.The aim of this experiment was to evaluate the effects of adding ascorbic acid 2-glucoside (AA2G), a water-soluble antioxidant and stable derivative of ascorbate, to the semen extender and compare it to the addition of vitamin C (Vit. C) and the fat-soluble antioxidant α-tocopherol (α-Toh), both individually and in combination, on the seminal variables of equine sperm submitted to cooling for 72 h. We used two ejaculates from 10 stallions and evaluated them for motility, membrane integrity, chromatin fragmentation, mitochondrial activity and lipid peroxidation. In the analysis of lipid pero...
Fodor L, Szenci O, Peters M, Varga J, Szemerédi G, Wyszoczky F.A total of seven Bacteroides ureolyticus strains were isolated from the cervix and the clitoral fossa of mares with vaginal discharge. No other bacteria capable of causing metritis or vaginitis were isolated from the samples. The isolated strains resembled Taylorella equigenitalis. Both species are catalase, oxidase and alkaline phosphatase positive, but, in addition to these characteristics, B. ureolyticus strains produced urease and they could not tolerate 10% O2. They also failed to be agglutinated in a hyperimmune serum raised against T. equigenitalis; however, B. ureolyticus and T. equige...
Campos-Junior PH, Costa GM, de Avelar GF, Segatelli TM, Lacerda SM, Aponte PM, de França LR.Morphometry is a classical quantitative method often used in biology to provide a data basis for functional interpretations/interactions of a particular organ or system. Herein we took advantage of this valuable approach to evaluate the spermatogonial stem cell niche using the horse testis and immunocytochemical localization of GFRA1 [glial cell line-derived neurotrophic factor receptor produced by Sertoli cells)] as an example. Using the NIH ImageJ free software, we describe in detail all the necessary steps to investigate this specific and crucial microenvironment. Based on several recently ...
Johnson AL, Becker SE, Roma ML.Standard bred mares that were cycling normally were treated beginning on Days 9 or 10 of the oestrous cycle with repeated pulses of GnRH (20 micrograms/h) and/or a single injection of prostaglandin (PG)F-2 alpha (alfaprostol, 3 mg), and were subsequently bled and palpated daily until the next ovulation. GnRH treatment increased serum concentrations of LH and progesterone at 4 days after the start of treatment compared to controls. The combination of PGF-2 alpha + GnRH treatment resulted in an immediate decline in serum progesterone values, and subsequently decreased the interval to next ovulat...
Wilsher S, Rigali F, Couto G, Camargo S, Allen WR.Historically, cryopreservation of equine embryos >300 μm gave poor pregnancy rates until researchers collapsed the blastocoele cavity and aspirated the blastocoele fluid prior to vitrification. Objective: To determine if aspiration of the blastocoele fluid prior to vitrification is essential for post warming survival. Methods: In vivo experiments. Methods: Fifty embryos were recovered on day 7-8 and washed in holding medium (HM; M-199HEPES + 20% FBS + antibiotics). Embryos were punctured using a micromanipulator mounted 30 μm biopsy needle; following this 28 had >90% of their bla...
Potter DA, Foss L, Baumler RE, Held DW.An equine disease now known as mare reproductive loss syndrome (MRLS) struck the Ohio Valley in 2001-2002 causing thousands of foal abortions and enormous economic loss. Evidence that pregnant mares' exposure to Eastern tent caterpillars Malacosoma americanum (F) induces MRLS created an urgent call for control measures suitable for use on horse farms. We surveyed egg mass distribution and monitored emergence in wild cherry trees, and evaluated reduced-risk treatment strategies including foliage sprays, trunk injections, winter egg mass treatments and barrier sprays to intercept larvae entering...
Maia VN, Batista AM, Cunha Neto S, Silva DM, Adrião M, Wischral A.The effects of deslorelin acetate use in inducing ovulation need to be clarified to improve the results of equine embryo transfer. The mRNA abundance for angiogenic factors and LH receptor (LHR) in corpus luteum (CL) was studied in mares with natural (control group [CG]) and induced ovulation with deslorelin acetate (treatment group [TG]; follicles: ≥ 35 mm). Transrectal ultrasonography was used to verify the ovulation day, and on Days 4, 8, and 12 after ovulation (Day 0), CL samples were obtained through ultrasound-guided biopsy. The messenger RNA expression of vascular endothelial growth f...
Rossetto L, Farcey MF, Bilbao MG, Bartolomé JA, Gallelli MF, Miragaya MH.The stress associated with training may reduce reproductive efficiency in Criollo stallions. The objective of this study was to compare semen quality and hormone concentrations in Criollo stallions under training or under regular field conditions. Criollo breed stallions (n = 18) were evaluated during the spring. The exercise group (n = 9) performed 1 hour of exercise per day and participated in competitions during the experimental period. The control group (n = 9) neither performed exercise nor participated in competitions. Serum and semen samples were obtained every 15 days (two separat...
Menzer C, Schams D.A double-antibody radioimmunoassay for PMSG, especially for meauring PMSG in cattle blood after exogenous application, has been developed. A rabbit antiserum against PMSG and pure PMSG for radioiodination were used. There was a strong cross-reaction against equine LH and FSH, but the slight cross-reaction against bovine LH and FSH could be eliminated by adding bovine LH to each tube during the assay. Unspecific, interfering influences of equine or cow serum could be eliminated by adding a constant amount of PMSG-free serum to each tube. PMSG added to 200 microliter of serum could be recovered ...
Waheed MM, Meligy A, Alhaider AK, Ghoneim IM.Seminal plasma contains several microelements like Zn, Fe, Se, and Cu that affect sperm motility and male fertility. Biochemical evaluation of seminal plasma trace elements is important for assessing fertility and diagnosing male infertility. Unassigned: The present study was designed to evaluate the effect of seminal fluid trace elements on sperm parameters and fertility in Arabian horses. Unassigned: Ninety-four ejaculates from 25 Arabian stallions (4-27 years old) were used to investigate the effect of seminal fluid trace elements on semen parameters and fertility. Data divided according to...
Haynes SE, Reisner AH.Although no major structural or numerical abnormalities were found in the karyotypes of 12 aborted equine fetuses, two unrelated abortuses each carried a large polymorphism for the amount of heterochromatin in chromosome 1. In both karyotypes this chromosome was shown to be larger than its homolog. To determine the nature of the extra DNA in these chromosomes, equine DNA was isolated and characterized by buoyant density analysis. Equine mainband DNA had a buoyant density in neutral CsCl of 1.699 g/cm3, while the highly repetitive (dG+dC)-rich fraction had a buoyant density of 1.715 g/cm3. A ra...
Silvia PJ, Squires EL, Nett TM.Four groups of mares, representing anestrus (AN; n = 8), early transition (ET; n = 7), late transition (LT; n = 8) and estrus (EST; n = 12) were used to examine release of luteinizing hormone (LH) and follicle stimulating hormone (FSH) after a bolus injection of gonadotropin releasing hormone (GnRH) during the transition from anestrus into the breeding season. Estrous mares received GnRH on d 2 or 3 of estrus in the cycle immediately preceding slaughter. Anestrous, ET and LT mares received GnRH exactly 1 wk prior to slaughter. A single injection of GnRH (Sigma LHRH, L-0507, 2.0 micrograms/kg b...
Dias AJ, Maia MS, Retamal CA, López ML.The expression of alpha-1,4-glucosidase activity was fluorometrically and electrophoretically assessed in the epididymal fluid and seminal plasma of stallions. alpha-Glucosidase specific activity in the epididymis increased significantly from the proximal caput to the cauda. Stallion epididymal glucosidase maintained activity in a wide range of pH, with two distinct peaks (around pH 4.0 and 6.0, respectively). Enzyme activities at different pH, inhibition assays with sodium dodecyl sulfate (SDS) and maltotriose (MTT, selective inhibitors of alpha-glucosidases "acidic" and "neutral" isoforms, d...
Martin KL, Hoffman RM, Kronfeld DS, Ley WB, Warnick LD.Changes in serum concentrations of Ca and parathyroid hormone (PTH) may develop in periparturient mares, may be influenced by dietary Ca, and may be associated with changes in Ca concentration of mammary secretion. Milk and blood samples were taken from eight mares on Farm A and eight on Farm B for 10 d before parturition and from four mares on each farm for 5 d postpartum. Milk Ca was measured by two commercial tests. Serum samples were analyzed for PTH and total Ca in 16 mares and for ionized Ca in six (Farm A). Parturition was induced in eight mares on Farm A and four on Farm B; no signific...
Kenney RM, Ganjam VK, Cooper WL, Lauderdale JW.Seventy-three Standardbred and Thoroughbred mares in clinical anoestrus during the breeding season were treated with PGF2alpha. The mares were divided into four categories; foaling, barren, maiden and unknown. The response was consistent in all groups. Mares at Days 2 to 4 of dioestrus showed no decrease in plasma progesterone levels, and those at Days 6 to 8 showed a return of progesterone to baseline levels (less than 1 ng/ml) in 24 to 48 hr after treatment. Plasma progesterone levels returned to basal levels in 24 to 48 hr in 93% of mares; progesterone levels had not changed by 96 hr in 7% ...
Faszer K, Draper D, Green JE, Morris GJ, Grout BW.A Stirling Cycle freezer has been developed as an alternative to conventional liquid nitrogen controlled rate freezers. Horse semen samples were cooled in 0.25 ml straws and 15 ml bags in the Stirling Cycle freezer under laboratory conditions and as a portable device, powered from a car battery. For comparison, straws were frozen in a conventional liquid nitrogen controlled rate freezer. Upon thawing, motility and viability of samples frozen in the Stirling Cycle freezer were not significantly different when compared to samples frozen in the liquid nitrogen freezer. Unlike liquid nitrogen syst...
Conforti VA, Vanderwall DK, Woods GL.The in vitro maturation (IVM) of equine oocytes is typically performed using various synthetic media; however, an optimal IVM system for equine oocytes has not been developed. The aim of the present study was to evaluate the effects of two types of follicular fluid (FF) obtained from cyclic mares and two incubation intervals for the IVM of equine cumulus-oocyte complexes (COCs). Follicular fluid was collected from medium-sized (20-29 mm diameter) and large (e30 mm; post-human chorionic gonadotrophin administration) follicles using transvaginal ultrasound-guided follicle aspiration. Compact (n ...
Ellington JE, Ball BA, Blue BJ, Wilker CE.Reliable capacitation of equine spermatozoa has been a major obstacle in the development of equine in vitro fertilization. Experiments were done to compare in vitro capacitation of equine spermatozoa by use of heparin/caffeine, calcium ionophore, uterine tube epithelial cell (UTEC)-conditioned medium, and direct culturing of spermatozoa with UTEC (coculturing). Capacitation-like changes, as determined by chlortetracycline membrane staining patterns, developed with UTEC-conditioned medium and coculturing, equivalent to that with calcium ionophore. Both of these treatments induced more (P < 0.05...
Allen WR.Genus-specific reproductive processes and strategies displayed by equids, camelids and elephantids are compared and contrasted to illustrate the amazing diversity of reproductive physiology between genera and the equally surprising conservation of reproductive processes across a genus in the face of other dramatic phenotypic modifications and adaptation to prosper in the prevailing environment. From intrauterine conceptus mobility and chorionic gonadotrophic secretion by specialised invasive trophoblast cells in equids, through induced ovulation, an asymmetrical uterus and an almost absurdly s...
Li JR, Wang W, Shi FX.The effects of equine chorionic gonadotropin (eCG) on follicular development and ovulation in cyclic guinea pigs were investigated by histological and immunohistochemical analyses. Three groups of guinea pigs (n=12) were administrated subcutaneously with saline, 20 or 50 IU of eCG, respectively, on cyclic Day 12 (Day 1=vaginal openings). Ovaries were collected at 4 and 8 d after administration (6 animals per group each time). The eCG administration induced significant and distinct morphological changes in the ovaries, as it promoted the luteinization of granulosa cells, but not follicular deve...
Westendorf J, Wobeser B, Epp T.Inter- and intra-rater variability negatively affects the reliability of various histopathology grading scales used as prognostic aids in human and veterinary medicine. The Kenney-Doig categorization (grading) scale, which is used to associate equine endometrial histologic lesions with prognostic estimation of a broodmare's reproductive potential, has not been evaluated for inter- or intra-rater variability, to our knowledge. To assess whether the Kenney-Doig system produces reliable results among observers, 8 pathologists, all with American College of Veterinary Pathologists certification, we...
Woods GL, Steiner JV.The objective of this project was to produce multiple pregnant recipient mares during one year from each of four mares which were in athletic training and competition. Twenty-six embryos were recovered from the four mares in 38 collection attempts. Each embryo was surgically transferred to one of 20 recipient mares. Nine of 10 recipient mares which were transferred to on one occasion were detected pregnant at the one week post transfer pregnancy examination and six of eight mares which were transferred to on two occasions were detected pregnant at one of the one-week post transfer pregnancy ex...
Teijeiro JM, Marini PE.The oviduct is a dynamic organ in which final gamete maturation, fertilization and early embryo development take place. It is considered to be a sterile site; however the mechanism for sterility maintenance is still unknown. S100A7 is an anti-microbial peptide that has been reported in human reproductive tissues such as prostate, testicle, ovary, normal cervical epithelium and sperm. The current work reports the presence of S100A7 in the Fallopian tube and its localization at the apical surface of epithelial cells. For comparison, porcine S100A7 was used for antibody development and search for...
Yoon J, Park T, Kim A, Park J, Park BJ, Ahn HS, Go HJ, Kim DH, Lee JB, Park SY, Song CS, Lee SW, Choi IS.Equine parvovirus-hepatitis (EqPV-H) is one of the etiological agents of Theiler's disease, causing fulminant hepatitis; however, its transmission route and pathogenesis remain unclear. In the present study, we aimed to determine EqPV-H shedding in oral/nasal/vaginal swabs or semen samples from horses living in Korea using nested polymerase chain reaction. We then used the data obtained to investigate various risk factors associated with EqPV-H including viral shedding, hepatopathological changes, and genetic diversity. Our data revealed occurrence of EqPV-H shedding in these animals (oral: 3/...
Carranza J, Yoong WA, Mateos C, Caño Vergara B, Gómez CL, Macías V.Horse reproduction tends to be seasonal. The main adjusting factor in their original temperate ranges is photoperiod variation, although it is absent in equatorial areas where horses were introduced by European colonizers. Hence, dates of reproduction in these areas may be influenced by factors affecting mares' conditions and the success of foaling. Here we study reproductive timing in Creole horses in Ecuador reared in an extensive production system. We found that foaling peaked in August. Mares' conditions showed one peak in June-July, before the start of the breeding season, and another in ...
Ginther OJ, Gastal EL, Gastal MO, Beg MA.The role of the insulin-like growth factor (IGF) system in the deviation in growth rates among follicles (follicle selection) was studied in mares using an IGF binding protein (BP) to reduce the follicular-fluid concentrations of IGFs. The future dominant follicle (F1) was treated by intrafollicular injection at the expected beginning of deviation (F1 > or = 20 mm; Day 0). The experimental groups were control (no injection, n = 8), vehicle (injection of vehicle; n = 6), and BP (injection of 250 microg of recombinant human IGFBP-3; n = 6). A sample of follicular fluid was taken from F1 on Da...
Freeman DA, Butler JE, Weber JA, Geary RT, Woods GL.Oviductal and uterine embryos were collected from mares at 5 to 7 days following ovulation 1) to evaluate the effects of oviductal tissue explants on in vitro growth and development of equine embryos and 2) to study the morphologic development of equine embryos in culture. Embryos were incubated for 5 days in a medium (control group) or in medium supplemented with oviductal tissue explants (co-culture group). Embryos were evaluated and the media changed daily. Following 5 days in culture, 10 10 (100%) control embryos and 27 29 (93%) co-cultured embryos had doubled in diameter. All embryos that...
Goericke-Pesch S, Hauck S, Failing K, Wehrend A.Membrane vesicles (MVs) in the ejaculate have been identified in various species and are considered to affect membrane fluidity due to their characteristic molecular composition. Addition of MV to human frozen semen has been shown to improve post-thaw motility. Similarly, a beneficial effect has been suggested for frozen equine semen. As post-thaw canine semen quality varies widely between dogs, the aim of our study was to test for the effect of addition of canine MV on post-thaw semen quality in dogs. Semen samples from 10 male dogs were purified from MV and prepared for freezing. In experime...
Lagares MA, Martins HS, Carvalho IA, Oliveira CA, Souza MR, Penna CF, Cruz BC, Stahlberg R, Henry MR.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...
