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.
Kelley DE, Schnobrich MR, Gayer S, Scoggin C, Bradcamp E, Canisso IF.The objective of this study was to compare a commercially available leukocyte esterase strip test with endometrial cytology in diagnosing endometritis and establish a cutoff point, sensitivity, and specificity for the leukocyte esterase test (LET). Forty-six light breed mares presented for breeding management were enrolled in this study. Transrectal palpation and ultrasonography examinations were performed to determine when the mares were in estrus. Kalayjian endometrial swabs were used for culture, cytology, and the LET by using the cap to retrieve an endometrial scraping. Thirty-six mares ha...
Pluháček J, Tučková V, King SRB, Šárová R.Overmarking occurs when one individual places its scent mark directly on top of the scent mark of another individual. Although it is almost ubiquitous among terrestrial mammals, we know little about the function of overmarking. In addition, almost all studies on mammalian overmarking behaviour dealt with adult individuals. Reports on this behaviour in juveniles are extremely rare, yet may elucidate the function of this behaviour. We tested four mutually non-exclusive hypotheses which might explain this behaviour in juveniles: (1) conceal the individual's scent identity, (2) announcement of ass...
Rota A, Sabatini C, Przybył A, Ciaramelli A, Panzani D, Camillo F.To increase sperm motility, several molecules have been tested in mammals. Methylxanthines have shown effects on sperm motility, capacitation, and on in vitro fertilization processes. The aim of the study was to evaluate if the post-thaw addition of caffeine and/or pentoxifylline changes motility parameters of cryopreserved stallion and donkey spermatozoa. Straws derived from 14 horses and 7 donkeys were thawed and diluted in a milk-based extender to obtain the following final concentrations: CTR (control, no additives), CAF 5 (5 mM caffeine), CAF 10 (10 mM caffeine), PTX 5 (5 mM pentoxify...
Sarnecky BA, Vanderwall DK, Mason HM, Kirschner SM, Ambrose B, Parker TL.Prolonging function of the corpus luteum (CL) is a method of suppressing estrus that relies on continued secretion of endogenous progesterone to keep mares out of heat naturally. The use of oxytocin treatment to prolong CL function is gaining increasing use, and the most common treatment protocol involves administration of 60 units of oxytocin intramuscularly (IM) once daily on days 7-14 after ovulation (eight daily treatments). Although that protocol induces prolonged CL function in ≥70% of treated mares, the need for daily administration is a drawback to its use. Therefore, the objective o...
Ginther OJ.Heifers have two or three major follicular waves per interovulatory interval (IOI). In mares and women, the ovulatory wave is the only major wave in most (75%) IOI. The beginning of diameter deviation during follicle selection of the future dominant follicle (DF) is followed by continued growth of DF and decreasing growth of the future subordinate follicles. Diameter deviation in Bos taurus heifers, mares, and women begins when the future DF is a mean of 8.5, 22.5, and 10.5 mm, respectively. Selection of the ovulatory follicle occurs more frequently from right ovary (RO) in heifers and women...
Devick IF, Hendrickson DA.To describe a standing left paralumbar fossa approach combined with mesocolon fenestration for bilateral equine ovariectomy. Methods: Prospective experimental clinical study. Methods: Four healthy client-owned mares and 1 client-owned Molly mule. Methods: Mares were restrained in standing stocks and sedated with an α -agonist continuous infusion to effect. The abdominal cavity was approached via a left paralumbar fossa approach, and the contralateral right ovary was accessed through an incision in the mesocolon. The location of the window was adjusted to allow triangulation, adequate visualiz...
Duguma A, Lemma A, Hibste A.Equine reproduction is unique by having long behavioral estrus and differences in time of breeding between breeds and individuals of mares. An experimental study was conducted at the Balderas Sport Horses and Recreational Center, Addis Ababa, Ethiopia, from January to June, 2018, to evaluate conception rate to frozen semen in local and exotic crossbreed mares. Mares were teased to characterize estrus behavior and examined by ultrasound in determining imminent ovulation. Inseminations were done post ovulation within an average of 6-9 h using frozen-thawed semen. The overall conception rate to ...
Camargo Ferreira J, Linhares Boakari Y, Sousa Rocha N, Saules Ignácio F, Barbosa da Costa G, de Meira C.The present study characterized the luteal status and the dynamic of the conceptus during the first 20 days of gestation in mares with different ages and degrees of endometrial degeneration. Total area of the corpus luteum (CL), luteal vascularity, CL area with blood signals, progesterone concentrations (P4), embryonic vesicle diameter, number of embryonic location changes, embryonic fixation position and uterine contractility were evaluated. In Experiment 1, mares ≤6 years of age (Young group, 5.6 ± 0.2 years, n = 7 mares) and mares ≥15 years of age (Old group, 17.2 ± 0.9 yea...
Alamaary MS, Haron AW, Ali M, Hiew MWH, Adamu L, Peter ID.Different types of extenders have a variety of components which show the tolerance effect on sperm protection during freezing procedures. In the present study, we have examined the impact of the extenders HF-20 and Tris, which were locally manufactured, and they are competing with commercial extenders INRA Freeze® (IMV Technologies, France) and EquiPlus Freeze® (Minitube, Germany) on the quality of horses frozen semen. Methods: A total of 15 ejaculates from three healthy stallions were collected and cryopreserved in the same environment. Each semen sample collected was divided into four equa...
Gonzalez-Castro RA, Carnevale EM.We determined if microfluidic sorting (MF) of frozen-thawed stallion sperm improves sperm population characteristics and results in embryo development after intracytoplasmic sperm injection (ICSI). The efficiency and efficacy of MF sperm separation was evaluated by comparing pre- and post-separation sperm population variables. Procedural comparisons were performed after sorting with MF, single-layer colloidal centrifugation (SLC) or swim-up (SU), and cleavage and embryo development were evaluated after ICSI using MF-sorted sperm. In Experiment 1, when compared to the original sperm sample, MF ...
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...
Hannan MA, Haneda S, Itami Y, Wachi S, Saitoh T, Cheong SH, Nambo Y.There has been no report of equine embryo transfer in Japan for the last 24 years. Our objective was to establish an effective protocol for embryo transfer in domestic horse. A Hokkaido native pony was bred by deep-horn artificial insemination with frozen semen from a Connemara pony. Embryo collection was performed using a non-surgical method on day 7. Two embryos were obtained from three flushes (67% recovery) and were transferred fresh into crossbred recipient mares. Both recipient mares were diagnosed pregnant (100% pregnancy rate) 5 days after embryo transfer and had normal progesterone le...
Buss T, Aurich J, Aurich C.In horse breeding, quality assessment of semen before insemination is often requested. Non-laboratory-based techniques for objective analysis of sperm motility are thus of interest. The aim of this study was evaluating a portable device for semen analysis (Ongo sperm test) and its comparison with computer-assisted semen analysis (CASA). Semen was collected from 10 stallions, diluted to 100, 50 and 25 × 106 sperm/ml and analysed for total (TM) and progressive motility (PM). The final sperm concentration influenced total motility analysed by Ongo (p < 0.05) which was higher at 100 × 10...
Rapacz-Leonard A, Leonard M, Chmielewska-Krzesińska M, Paździor-Czapula K, Janowski T.Major histocompatibility protein class I (MHC-I) is believed to be expressed in the horse allantochorion only in limited areas at limited times. However, its expression has only been investigated in early pregnancy with non-quantitative techniques that cannot reliably detect small amounts of protein. To quantify the relative expression of MHC-I in the allantochorion and endometrium during days 90-240 of pregnancy (PREG), parturition with physiological delivery of fetal membranes (PHYS), and parturition with retention of these membranes (FMR). Also, to visualize protein expression and determine...
Treulen F, Aguila L, Arias ME, Jofré I, Felmer R.During cryopreservation procedures, the spermatozoa are exposed to physical and chemical stressors that generate an increase in the intracellular concentration of reactive oxygen species (ROS). If ROS concentrations are too great, this can lead to a state of oxidative stress that are detrimental to sperm quality. The aim of this study was to ascertain the profile the ROS production and assess the effects of post-thaw supplementation of a semen extender with different antioxidant compounds on the quality and function variables of frozen-thawed stallion spermatozoa incubated in vitro. Frozen-tha...
Soni Y, Talluri TR, Kumar A, Ravi SK, Mehta JS, Tripathi BN.Traditionally Glycerol (Gly) is being used as major cryoprotectant and its toxicity could be a reason for the variation on stallion sperm freezability and fertility. In an effort to minimize Gly toxicity alternative cryoprotective agents like Di-methyl Formamide (DMF) have been investigated. The effect of the cryoprotectant and dose of cryoprotective agent varies from breed to breed and also from stallion to stallion within the same breed. Considering these factors a study was designed to study the effects of Gly and DMF at different concentrations and combinations on the plasma membrane, acro...
Swegen A, Smith ND, Gibb Z, Curry BJ, Aitken RJ.Serine proteases are emerging as important players in the spermatozoon's acquisition of functional competence. This study aimed to characterize the serine protease testisin (PRSS21) in stallion spermatozoa, examining its surface expression, possible origins in the testis and epididymis, and changes in response to capacitation and acrosome reaction, as well as its capacity to form high molecular weight complexes and interact with other proteins. The role of serine proteases in spontaneous capacitation and acrosome reaction of stallion spermatozoa was established using the serine protease inhibi...
Lanci A, Castagnetti C, Ranciati S, Sergio C, Mariella J.In the mare, foaling is a critical unpredictable event due to a wide range of gestational length and the absence of clear signs of impending parturition. To predict foaling, pH, inversion sodium potassium and increase of calcium concentration in mammary secretions are used. The aim of this study was to find how many days are left until parturition knowing mare's age (A) and parity (P) combined with ultrasonographic measurements of the fetal orbit in Standardbred mares with normal pregnancy. Eighty healthy Standardbred mares with normal pregnancy were hospitalized for attended delivery. Informa...
Maloney SE, Khan FA, Chenier TS, Diel de Amorim M, Anthony Hayes M, Scholtz EL.Proteomic analysis of mare uterine flush fluid provides a minimally invasive technique for studying protein changes associated with the oestrous cycle. The aim of this study was to identify differentially abundant proteins in the uterine flush fluid of mares in oestrus and dioestrus. In this study, uterine flush fluid samples were collected from eight reproductively healthy mares in either oestrus (n = 5) or dioestrus (n = 3). Proteomic analysis was performed using liquid chromatography-tandem mass spectrometry. Of 172 proteins identified, six proteins (immunoglobulin lambda-like polypepti...
Rigoglio NN, Matias GSS, Miglino MA, Mess AM, Jacob JCF, Smith LC.Hybrids between species are often infertile and extremely rare among mammals. Mules, i.e. crossing between the horse and the donkey, on the other hand are very common in agricultural and leisure practices due to their enhanced post-natal physical characteristics that is believed to occur for outbreeding or hybrid vigor. Since no reports are availableon the effects of hybrid vigor during early development, this study focused on characterizing the intrauterine development of mule conceptuses during critical embryo-to-fetus transition period. Nine embryos and fetuses of early gestation, obtained ...
Elsohaby I, Riley CB, McClure JT.Neonatal foals with failure of transfer of passive immunity (FTPI) are at higher risk of morbidity and mortality. Successful treatment of FTPI is time-dependent, thus rapid and accurate measurement of serum IgG concentration is important for the management and care of neonatal foals. Objective: To validate the use of digital and optical refractometers for assessing FTPI in neonatal foals and compare the diagnostic performance and level of agreement of the two refractometers to the reference standard radial immunodiffusion (RID) assay. Methods: A retrospective validation study. Methods: Serum s...
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...
Moro LN, Amin G, Furmento V, Waisman A, Garate X, Neiman G, La Greca A, Santín Velazque NL, Luzzani C, Sevlever GE, Vichera G, Miriuka SG.Cell reprogramming has been well described in mouse and human cells. The expression of specific microRNAs has demonstrated to be essential for pluripotent maintenance and cell differentiation, but not much information is available in domestic species. We aim to generate horse iPSCs, characterize them and evaluate the expression of different microRNAs (miR-302a,b,c,d, miR-205, miR-145, miR-9, miR-96, miR-125b and miR-296). Two equine iPSC lines (L2 and L3) were characterized after the reprogramming of equine fibroblasts with the four human Yamanaka's factors (OCT-4/SOX-2/c-MYC/KLF4). The plurip...
Gastal GDA, Aguiar FLN, Ishak GM, Cavinder CA, Willard ST, Ryan PL, Feugang JM, Gastal EL.Preservation of cellular integrity and its mechanisms after ovarian tissue cryopreservation (OTC) and in vitro culture (IVC) procedures are crucial aspects for the success of preservation and recovery of female fertility. This study aimed to evaluate the effects of two cryopreservation methods (slow-freezing, SF, and vitrification, VIT) on the equine ovarian tissue after 1, 3, and 7 days of IVC by assessing: (i) preantral follicle morphology and distribution of follicle classes; (ii) protein expression of markers of cell proliferation for EGFR and Ki-67; (iii) markers of apoptosis for Bax and...
Pégné JC, Duquesne F, Laugier C, Lequeux G, Petry S.The present study reports the isolation of A. hippocoleae from genital swabs of 15 apparently healthy mares (at least one had an abortion one month earlier) and describes the genotypic and phenotypic characterisation of these strains. The mares were of eight different breeds with a thoroughbred dominance and came from 11 breeding farms located in the French region of Brittany. 16S rRNA gene sequencing confirmed the species' identification by comparing it with reference strain A. hippocoleae CIP 106850. Some degree of natural divergence within A. hippocoleae was observed by 16S rRNA sequencing ...
Jaworska J, Janowski T.Retained fetal membranes (RFM) is a prevalent postpartum disease in mares. During parturition, various proinflammatory cytokines are released in the placenta, which further facilitates uterine contractions, expulsion of the fetus and fetal membranes. We hypothesized that an altered inflammatory response in mares results in retained fetal membranes. Samples of the endometrium and the allantochorion were collected from 15 mares with RFM and from 29 control mares within 2 h of foal delivery. Next, the mRNA expression of IL-1β, IL-6 and TNFα proteins was analyzed by Real Time PCR and Western b...
Farstad W.Ethical breeding involves the use of healthy animals true to their species in behaviour and physical appearance, and when applicable, showing a sustainable performance. The concerns for the species/breed are essential parts of the breeding goals, including preservation of genetic resources within the species/breed, and the health and welfare of the individual animal. Ethical and welfare considerations were often not prioritized in developing new breeds of production or companion animals. As a result, animal breeding practices are increasingly becoming part of the debate on animal welfare. In c...
Cuervo-Arango J, Claes AN, Stout TAE.Equine embryos tolerate an unusually large degree of negative uterine asynchrony (recipient mare up to 5 days behind the donor mare). By contrast, positive asynchrony of more than 2 days results in a high incidence of early embryonic loss (EEL). Day 8 embryos range in diameter from approximately 130-1300 μm, with embryos smaller than 300 μm reported to suffer an increased incidence of EEL. However, it is not known whether this reduced viability is due to intrinsically poor embryo quality, or to inadvertent recipient uterine stage-embryo (positive) asynchrony. To examine whether small emb...
Grady ST, Watts AE, Thompson JA, Penedo MCT, Konganti K, Hinrichs K.This study aims to determine if intra-ovarian injection of bone marrow-derived mesenchymal stem cells (MSCs) improves or restores ovarian function in aged females. Methods: Prospective randomized study of eight aged mares and six young mares receiving intra-ovarian injection of MSCs or vehicle. Main outcome measures were antral follicle count and serum anti-Müllerian hormone (AMH) (aged and young mares), and for aged mares, oocyte meiotic and developmental competence; gross and histological ovarian assessment; evaluation of presence of chimerism in recovered granulosa cells and in ovarian tis...
Ball BA, El-Sheikh Ali H, Scoggin KE, Riddle WT, Schnobrich M, Bradekamp E, Agnew M, Squires EL, Troedsson MHT.The objectives of this study were to evaluate; 1) the stability of measured serum anti-Müllerian hormone (AMH) concentrations in samples after multiple freeze-thaw cycles, 2) the repeatability of AMH concentrations within mares during the same breeding season as well as across breeding seasons, and 3) the relationship between serum AMH concentrations and fertility (measured as first cycle pregnancy rates) in thoroughbred mares. For the first aim, AMH concentrations (n = 9) were examined across four freeze-thaw cycles with no significant change in measured AMH concentrations. For the second ...
Alghamdi AS, Funnell BJ, Bird SL, Lamb GC, Rendahl AK, Taube PC, Foster DN.We performed a series of comparative studies of bull and stallion seminal plasma (SP) and its role on sperm-neutrophil binding as well as the interaction between semen extender and seminal DNase. Because of contrasting roles of SP on sperm-neutrophil binding between horses and cattle, it was suspected there were some species-specific differences on sperm interaction with SP proteins due to the variations in the natural location of semen deposition (uterus compared to vagina). Bull frozen-thawed sperm removed from egg yolk extender showed similar results to fresh sperm, but this also caused ext...
Beythien E, Wulf M, Ille N, Aurich J, Aurich C.In pregnant mares, peripheral insulin antagonism channels glucose preferentially to the foetus. On the other hand, horses reduce their metabolic activity in winter. Taking these aspects of equine pregnancy and metabolism together, we hypothesized that glucose clearance from blood and the insulin response to glucose do not only change throughout gestation but also with season. To test this hypothesis, the glucose and insulin response to an oral glucose test and relative insulin release were analysed in pregnant mares (n=12) and in geldings (n=10) as controls. Animals were tested in June, Septem...
Amaral A, Fernandes C, Rebordão MR, Szóstek-Mioduchowska A, Lukasik K, Pinto-Bravo P, Telo da Gama L, Jan Skarzynski D, Ferreira-Dias G.Neutrophils can originate neutrophil extracellular traps (NETs). Myeloperoxidase (MPO) is a peroxidase found in NETs associated to equine endometrosis and can be inhibited by 4-aminobenzoic acid hydrazide (ABAH). Metallopeptidases (MMPs) participate in extracellular matrix stability and fibrosis development. The objectives of this in vitro work were to investigate, in explants of mare's endometrium, (i) the ABAH capacity to inhibit MPO-induced collagen type I (COL1) expression; and (ii) the action of MPO and ABAH on the expression and gelatinolytic activity of MMP-2/-9. Explants retrieved from...
Katila T.The article reviews methods used for in vitro evaluation of sperm, with particular emphasis on frozen-thawed stallion sperm. The techniques, limitations of the methods and correlations with fertility results are discussed. Very few studies have tried to find correlation between fertility of frozen stallion semen and laboratory tests. It is difficult and expensive to inseminate an adequate number of mares to achieve statistically significant differences. Significant, but low correlations have been demonstrated between the foaling rate and subjective motility of sperm incubated for 2 h and 4 h a...
Fradinho MJ, Correia MJ, Grácio V, Bliebernicht M, Farrim A, Mateus L, Martin-Rosset W, Bessa RJ, Caldeira RM, Ferreira-Dias G.The aim of this study was to investigate the effects of body condition (BC), BC changes, and plasma leptin concentrations on the reproductive performance of Lusitano broodmares on extensive systems. Data from 119 mares (ranging from 4 to 22 years of age) were collected over a period of four consecutive breeding seasons. Each case was considered as one foaled mare bred in 1 year. Body condition changes at conception (ΔBCScon) showed a strong effect on fertility at the first two postpartum estrous cycles and a significant interaction with body condition score at conception (BCScon) was observed...
Metcalf ES.Despite the numerous benefits of having the capability to transport semen internationally, there are serious potential ramifications if that semen is contaminated with a communicable disease. Bacteria: Many commensal bacteria colonize the exterior of the stallion penis and are not regarded as pathogenic. They may be cultured from an ejaculate. Alterations of the normal bacterial flora on the exterior genitalia may cause the growth of opportunistic bacteria such as Klebsiella pneumonia, Pseudomonas aeruginosa, Streptococcus zooepidemicus, which, if inseminated, may cause infertility in suscepti...
Papa FO, Felício GB, Melo-Oña CM, Alvarenga MA, De Vita B, Trinque C, Puoli-Filho JN, Dell'Aqua JA.The objective of this study was to determine whether replacing the egg yolk with soybean lecithin in the Botu-Crio® cryodiluent would maintain the fertility of cryopreserved stallion sperm. Two experiments were performed to evaluate cell freezability. In experiment 1, sperm from 15 stallions were frozen in Botu-Crio® (BC) or Botu-Crio® which contained 45g/L soybean lecithin (BCLS45) in place of the egg yolk. In experiment 2, we compared different concentrations of soybean lecithin: 0, 10.0, 12.5, 15.0, 17.5 and 20.0g/L (BC, BCLS10, BCLS12.5, BCLS17.5 and BCLS20, respectively). In experiment...
Auclair-Ronzaud J, Jousset T, Dubois C, Wimel L, Jaffrézic F, Chavatte-Palmer P.Gestational length is highly variable in horses ranging from 320 to 360 days. Thus, determining parturition time is an important challenge for the horse industry. Body temperature can be used in cows and ewes as an indicator of parturition. Thus, the aim of this study is to determine if temperature can also be used as indicator of foaling. Thirty-nine mares were monitored over two foaling seasons (2018 and 2019). They were housed in 16 m stalls with access to pasture in group three times a week from 10:00 to 16:00. Night watch as well as video monitoring was ensured during foaling periods. Bo...
Ruiz AJ, Tibary A, Heaton RA, Hargreaves IP, Leadon DP, Bayly WM.Although coenzyme Q10 (CoQ10) serves as an antioxidant and energy source for spermatozoa when added to stallion semen before cooling or freezing, the effects of feeding CoQ10 on semen quality have not been studied. We assessed the effects of daily oral ingestion of CoQ10-ubiquinol by stallions on their plasma CoQ10 concentrations and semen quality. Seven mature Andalusian stallions ate 1g ubiquinol/day for 4 weeks followed by a 4-week washout period. Four horses initially completed an additional 4-week control period without ubiquinol. Blood was sampled weekly for determination of plasma CoQ1...
Pereira GR, Lorenzo PL, Carneiro GF, Ball BA, Bilodeau-Goeseels S, Kastelic J, Pegoraro LM, Pimentel CA, Esteller-Vico A, Illera JC, Granado GS....The objectives of this study were to evaluate the effects of equine growth hormone (eGH) on nuclear and cytoplasmic maturation of equine oocytes in vitro, steroid production by cumulus cells, and expression and subcellular localization of eGH-receptors (eGH-R) on equine ovarian follicles. Cumulus-oocyte complexes (COCs) were recovered by aspirating follicles <30 mm in diameter from abattoir-derived ovaries. The COCs were morphologically evaluated and randomly allocated to be cultured in either a control maturation medium or supplemented with 400 ng/mL eGH, for 30 h at 38.5°C in air with 5%...
Rosengren MK, Sigurðardóttir H, Eriksson S, Naboulsi R, Jouni A, Novoa-Bravo M, Albertsdóttir E, Kristjánsson Þ, Rhodin M, Viklund Å, Velie BD....The back plays a vital role in horse locomotion, where the spine functions as a spring during the stride cycle. A complex interaction between the spine and the muscles of the back contribute to locomotion soundness, gait ability, and performance of riding and racehorses. Conformation is commonly used to select horses for breeding and performance in multiple horse breeds, where the back and croup conformation plays a significant role. The conformation of back and croup plays an important role on riding ability in Icelandic horses. However, the genes behind this trait are still unknown. Therefor...
Soni Y, Talluri TR, Kumar A, Ravi SK, Mehta JS, Tripathi BN.Traditionally Glycerol (Gly) is being used as major cryoprotectant and its toxicity could be a reason for the variation on stallion sperm freezability and fertility. In an effort to minimize Gly toxicity alternative cryoprotective agents like Di-methyl Formamide (DMF) have been investigated. The effect of the cryoprotectant and dose of cryoprotective agent varies from breed to breed and also from stallion to stallion within the same breed. Considering these factors a study was designed to study the effects of Gly and DMF at different concentrations and combinations on the plasma membrane, acro...
Dell'Aquila ME, Masterson M, Maritato F, Hinrichs K.There is a great variability in the success of horse oocyte maturation and fertilization among laboratories. This study was conducted to determine if the meiotic and developmental competence of horse oocytes could be dependent on the method of oocyte collection, i.e., aspiration of follicular fluid with a vacuum apparatus, or opening follicles and scraping the granulosa layer. Horse oocytes were recovered from abattoir ovaries by aspiration or scraping and classified as having compact (Cp), expanded (Ex), or partial (P) cumuli. In Experiment 1 (Part A in May and Part B in October), oocytes wer...
Ferreira-Dias G, Bravo PP, Mateus L, Redmer DA, Medeiros JA.Corpus luteum growth and endocrine function are closely dependent on the formation of new capillaries. The objectives of this study were to evaluate (i) tissue growth and microvascular development in the equine cyclic luteal structures; (ii) in vitro angiogenic activity of luteal tissues in response to luteotrophic (LH, PGE(2)) and luteolytic (PGF(2alpha)) hormones and (iii) to relate data to luteal endocrinological function. Our results show that microvascular density was increased in the early and mid luteal phase, followed by a fall in the late luteal phase and a further decrease in the cor...
Laseca N, Molina A, Ramón M, Valera M, Azcona F, Encina A, Demyda-Peyrás S.The loss of genetic variability in livestock populations bred under strict selection processes is a growing concern, as it may lead to increased inbreeding values and lower fertility, as a consequence of the "inbreeding depression" effect. This is particularly important in horses, where inbreeding levels tend to rise as individuals become more and more closely related. In this study, we evaluated the effect of increased inbreeding levels on mare fertility by combining an SNP-based genomic approach using runs of homozygosity and the estimation of genetic breeding values for reproductive traits ...
The Journal of nutritionNovember 1, 1986
Volume 116, Issue 11 2142-2147 doi: 10.1093/jn/116.11.2142
Schryver HF, Oftedal OT, Williams J, Soderholm LV, Hintz HF.Changes in the mineral composition of mare milk during lactation were studied. Milk samples were obtained from five Thoroughbred mares one to three times weekly from the first to the eighth week of lactation and from two of the mares for an additional 8 wk. Samples averaging 500 mL were obtained after oxytocin was administered to the mares. Each sample was analyzed for total solids, ash, calcium, phosphorus, magnesium, sodium, potassium, copper and zinc. The concentration of all constituents except sodium and potassium decreased throughout lactation. The rates of decline of ash, calcium, phosp...
Berg EL, McNamara DL, Keisler DH.The aim of this study was to characterize concentrations of leptin, IGF-I, and thyroid stimulating hormone (TSH) in the blood serum of mares pre-and postpartum, in the milk serum of mares postpartum, and in the blood serum of their foals. Nine pregnant Quarter Horse mares and their offspring were used in this study. Once weekly between 1000 and 1200 h for 2 wk before their predicted parturition date, mares were weighed, assigned a BCS, and blood was sampled via jugular venipuncture. Within 2 h of parturition and before the foals nursed (d 0), blood samples were obtained from the mares and foal...
Yamada M, Gentry PA.The coagulation factors VII and X and fibrinogen were detected in equine ovarian follicular fluid. The amounts of fibrinogen and factor X were approximately 40 percent of that found in normal equine plasma while the level of factor VII was lower, at approximately 14 percent. The addition of human recombinant tissue factor caused fibrin formation in the follicular fluid. The thrombin generating activity appears to be confined to the tissue factor pathway since no activity associated with factors VIII:C, IX or IX was detected. Fibrinolytic activity, at higher levels than that found in plasma, wa...
Arnold CE, Payne M, Thompson JA, Slovis NM, Bain FT.To determine signalment, physical examination and clinicopathologic abnormalities, outcome, and subsequent fertility of mares with periparturient hemorrhage (PPH) and identify factors associated with outcome (ie, survival vs death). Methods: Retrospective case series. Methods: 73 mares. Methods: Medical records were reviewed for information on age, breed, initial complaint, physical examination and clinicopathologic abnormalities, treatment, outcome, and subsequent fertility. Results: Median age was 14.0 years (range, 5 to 24 years), and median number of foals produced prior to the diagnosis o...
Pasing S, von Lewinski M, Wulf M, Erber R, Aurich C.The aim of this study was to evaluate the stress response of stallions (n = 16) aged 3-13 years with previous sexual experience to semen collection by determination of heart rate, heart rate variability, and cortisol in saliva. Recordings were done on two consecutive days. The time intervals from leaving the box until arrival in the collection barn and from first exposure to the teaser mare until ejaculation as well as the number of mounts until ejaculation were neither affected by collection day nor by age, sexual experience (i.e., the number of breeding seasons the stallion experienced), or ...
McDowell KJ, Adams MH, Adam CY, Simpson KS.Two experiments were performed to determine changes in the abundance of oestrogen and progesterone receptor (ER alpha and PR) mRNAs in equine endometrium during the oestrous cycle and early pregnancy, and under the influence of exogenous steroids. In Expt 1, endometrial biopsies were obtained from non-mated mares during oestrus and at days 5, 10 and 15 after ovulation, and from pregnant mares at days 10, 15 and 20 after ovulation. There were overall effects of day on the abundance of ER alpha (P = 0.0001) and PR (P = 0.0014) mRNAs. The amount of ER alpha mRNA decreased at day 10 of pregnancy, ...
Crossett B, Suire S, Herrler A, Allen WR, Stewart F.One of the major, progesterone-dependent proteins secreted into the uterine lumen of the mare is a 19-kDa lipocalin (P19). It associates strongly with the embryonic capsule that envelops the young horse conceptus in early gestation, suggesting that it may be involved in sustaining early development. However, it was not known whether the protein was transported through the capsule and/or trophoblast layer and into the yolk sac cavity. To address this question, polyclonal antisera were raised against a C-terminal peptide (based on the deduced amino acid sequence of P19) and a recombinant-derived...
Terron-Canedo N, Weir W, Nicolson L, Britton C, Nasir L.Bovine papillomavirus (BPV) types 1 and 2 play an important role in the pathogenesis of equine sarcoids (ES), the most common cutaneous tumour affecting horses. MicroRNAs (miRNAs), small non-coding RNAs that regulate essential biological and cellular processes, have been found dysregulated in a wide range of tumours. The aim of this study was to identify miRNAs associated with ES. Differential expression of miRNAs was assessed in control equine fibroblasts (EqPalFs) and EqPalFs transformed with the BPV-1 genome (S6-2 cells). Using a commercially available miRNA microarray, 492 mature miRNAs we...
Veronesi MC, Villani M, Wilsher S, Contri A, Carluccio A.The aim of the study was to compare horse and donkey placentae using stereological techniques. Term placentae were collected at spontaneous foaling from seven Thoroughbred mares, seven pony mares, and six jenny donkeys. Maternal and foal weights were recorded and the mass, volume, and gross area of each allantochorion was also recorded. Ten random biopsies were recovered and processed for light microscopy from which the surface density of the microcotyledons (S(v)) and the total microscopic area of fetomaternal contact were calculated stereologically. Gestation length was longer in the donkeys...
Griggers S, Paccamonti DL, Thompson RA, Eilts BE.Urospermia has been reported as a cause of infertility in numerous species. The detrimental effects of urine on spermatozoa are due, at least in part, to changes in pH and osmolarity. Semen was collected and subjected to conditions of varying pH (Experiment 1), of varying osmolarity (Experiment 2), and various quantities and concentrations of urine (Experiment 3) and effects on motility were recorded. Finally, semen was contaminated with urine and then either of 2 semen extenders was added, with or without centrifugation, in an attempt to alleviate the detrimental effect of urine on motility (...
Klein C.Relaxin is a peptide hormone best known for its action during the latter half of pregnancy, in particular for its softening effect on pelvic ligaments that aids in preparation of the birth canal for the impending delivery of the fetus. The source of relaxin during early pregnancy varies across species, with the CL being the main source in a number of species. The main source of relaxin during late equine pregnancy is the placenta. In mares with impaired placental function, circulating relaxin levels decline before abortion. During early pregnancy, relaxin promotes endometrial angiogenesis thro...
Burger D, Dolivo G, Wedekind C.Sperm competition theory predicts semen characteristics to be affected by the social environment. We used the polygamous horse (Equus caballus) to experimentally study within-subject plasticity in response to different social environments. Stallions were sequentially exposed, over a period of 8 weeks each, to other stallions and then singly to mares, or vice versa (in adjacent boxes separated by grills). Ejaculates were collected to determine semen characteristics. Highest sperm numbers were found in stallions that were first exposed to other stallions and then to mares, while lowest sperm num...
Rathbone P, Arango-Sabogal JC, De Mestre AM, Scott CJ.Antimicrobial resistance (AMR) is important in equine reproduction, as antimicrobials have historically been widely used in the management of breeding mares. However, evidence of the characteristics of AMR in uterine isolates is limited in the UK. The objective of this retrospective study was therefore to describe temporal changes in AMR patterns of bacteria isolated from the endometrium of Thoroughbred broodmares in south-east England between 2014 and 2020. Endometrial swabs were processed for microbiology and antimicrobial susceptibility testing (AST). For frequently isolated bacteria, chang...
Sayasith K, Bouchard N, Doré M, Sirois J.The mammalian ovulatory process is accompanied by a gonadotropin-dependent increase in follicular levels of prostaglandin E2 (PGE2) and PGF2alpha, which are metabolized by 15-hydroxy prostaglandin dehydrogenase (PGDH). Little is known about ovarian PGDH regulation in non-primate species. The objectives of this study were to characterize the structure of equine PGDH and its regulation in follicles during human chorionic gonadotropin (hCG)-induced ovulation. The full-length equine PGDH was obtained by RT-PCR, 5'- and 3'-rapid amplification of cDNA ends (RACE). Its open reading frame encodes a 26...
Schwarzenberger F, Möstl E, Bamberg E, Pammer J, Schmehlik O.Faecal samples were collected at weekly intervals from pregnant Lipizzan mares during Weeks 7-16 following mating and from Lipizzan, Trotter and Thoroughbred mares during the last 3 months of gestation. After parturition, samples were taken daily from the Thoroughbred mares for another 6 days. Non-pregnant mares served as controls. The concentrations of unconjugated oestrogens (Eg), 20 alpha-OH-progestagens (20 alpha-G) and 20 beta-OH-progestagens (20 beta-G) were measured by enzyme immunoassay. In the faeces of Lipizzan mares, immunoreactive progestagens were significantly (P less than 0.01) ...
