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Topic:Mares
Mares and horses are integral components of equine studies, focusing on the reproductive and behavioral aspects of equine biology. Mares, or adult female horses, play a significant role in breeding programs and are often studied for their reproductive physiology, gestation, and maternal behaviors. Horses, as a broader category, encompass both sexes and all age groups, providing a comprehensive view of equine anatomy, physiology, and behavior. Research in this area often investigates the differences and similarities between mares and other horses in terms of hormonal cycles, reproductive health, and social interactions. This page compiles peer-reviewed studies and scholarly articles that explore the biological and behavioral characteristics of mares and horses, offering insights into their roles in equine science and management.
Passive transfer of maternal immunoglobulin isotype antibodies against tetanus and influenza and their effect on the response of foals to vaccination. Influenza and tetanus-specific antibodies of the IgG sub-isotypes are posively transferred to foals via colostrum and inhibit their response to inactivated influenza vaccines and tetanus toxoid. High titres of influenza antibodies of IgGa and IgGb subisotypes and tetanus antibodies of the IgGa, IgGb and IgG(T) subisotypes were detected in postsucking serum samples collected from foals born to mares that had received booster doses of multicomponent vaccines during the last 2 months of gestation. Thereafter, titres declined in an exponential manner but were still detectable in all foals at age 2...
Equine sperm-oocyte interaction: results after intraoviductal and intrauterine inseminations of recipients for oocyte transfer. Insemination of recipients for oocyte transfer and gamete intrafallopian transfer (GIFT) in five experiments were reviewed, and factors that affected pregnancy rates were ascertained. Oocytes were transferred into recipients that were (1) cyclic and ovulated at the approximate time of oocyte transfer, (2) cyclic with aspiration of the preovulatory follicle, and (3) noncyclic and treated with hormones. Recipients were inseminated before, after, or before and after transfer. Intrauterine and intraoviductal inseminations were done. Pregnancy rates were not different between cyclic and noncyclic r...
Advances in cryopreservation of stallion semen in modified INRA82. In the procedure used in this paper, semen was first diluted in INRA82+2% egg yolk (E1) at 37 degrees C. Before or after cooling to 4 degrees C, semen was centrifuged and diluted in E1+2.5% glycerol (E2). Cooled semen was frozen in 0.5-ml straws. Straws were thawed at 37 degrees C for 30s. For fertility trials, frozen ejaculates were used only if total post-thaw motility was above 35%. Most mares were inseminated two times before ovulation with 400 x 10(6) total spermatozoa every 24h. This paper presents post-thaw motility (CASA) and fertility results obtained when some steps of the procedure ...
The role of international transport of equine semen on disease transmission. 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...
Capacitation and the acrosome reaction in equine sperm. During sexual reproduction, the sperm and oocyte must fuse before the production of a diploid zygote can proceed. In mammals such as equids, fusion depends critically on complex changes in the plasma membrane of the sperm and, not surprisingly, this membrane differs markedly from that of somatic cells. After leaving the testes, sperm cease to synthesize plasma membrane lipids or proteins, and vesicle-mediated transport stops. When the sperm reaches the female reproductive tract, it is activated by so-called capacitation factors that initiate a delicate reorientation and modification of molecul...
Low dose insemination of mares using non-sorted and sex-sorted sperm. Mares are generally inseminated with 500 million progressively motile fresh sperm and approximately 1 billion total sperms that have been cooled or frozen. Development of techniques for low dose insemination would allow one to increase the number of mares that could be bred, utilize stallions with poor semen quality, extend the use of frozen semen, breed mares with sexed semen and perhaps reduce the incidence of post-breeding endometritis. Three low dose insemination techniques that have been reported include: surgical oviductal insemination, deep uterine insemination and hysteroscopic insemin...
Interaction between equine semen and the endometrium: the inflammatory response to semen. Insemination of mares with bacteria-free equine spermatozoa results in an influx of polymorphonuclear neutrophils (PMNs) into the uterine lumen. In vitro studies have demonstrated that equine spermatozoa activate complement, resulting in cleavage of factors C5a and C3b. Since uterine secretion is rich in complement, it is likely that an interaction between spermatozoa and uterine secretion results in C5a-mediated chemotaxis and migration of PMNs into the uterine lumen. Once in the uterine lumen, the PMNs phagocytize bacteria and spermatozoa, which is an important part of sperm elimination from...
The equine frozen semen industry. Recent acceptance of frozen semen as a method to produce registered foals by two of the worlds largest breed associations, the American Quarter Horse and American Paint Horse, has stimulated new interest in frozen semen technology. This review will: (a) attempt to identify the major impediments to the development of the frozen semen industry, (b) suggest alternative methods for marketing and application of frozen semen, and (c) present the results of a recent study in our laboratory. The objective of which was to compare pregnancy rates of insemination with cooled and frozen semen. Major imped...
Equine sperm-oocyte interaction: the role of sperm surface hyaluronidase. The plasma membrane over the sperm head of several mammalian species has been shown to express a glycerolphosphatidylinositol-linked hyaluronidase known as PH-20. This protein has been associated with the sperm's interaction with the oocyte cumulus matrix and zona pellucida. The characteristics of PH-20 in equine sperm have not been clearly defined. In this study, ejaculated gel-free semen from five stallions and epididymal sperm from isolated epididymis from 10 stallions was used to characterize the PH-20 activity in equine sperm. Affinity purified anti-equine PH-20 polyclonal antibody was us...
Sperm-uterine interactions: a review. The uterus of domestic animals, including the horse, has a dual role in the interaction of the uterus and sperm. On one hand, uterine contractions carry sperm toward the oviduct, and on the other hand the uterus eliminates excessive sperm. The selection of sperm for the small numbers of "good" cells that gain access to the oviduct and for the majority of sperm that will be destroyed takes place in the uterus. The sperm-uterine interaction works both ways; sperm and seminal plasma also have several effects on the uterus. Sperm and seminal plasma probably provoke uterine contractions. Sperm indu...
Management and fertility of mares bred with frozen semen. Semen quality, mare status and mare management during estrus will have the greatest impact on pregnancy rates when breeding mares with frozen semen. If semen quality is not optimal, mare selection and reproductive management are crucial in determining the outcome. In addition to mare selection, client communication is a key factor in a frozen semen program. Old maiden mares and problem mares should be monitored for normal cyclicity and all, except young maidens, should have at least a uterine culture and cytology performed. Mares with positive bacterial cultures and cytologies should be treate...
Elevated extrahepatic expression and secretion of mammary-associated serum amyloid A 3 (M-SAA3) into colostrum. Mammary-associated serum amyloid A 3 (M-SAA3) was secreted at highly elevated levels in bovine, equine and ovine colostrum and found at lower levels in milk 4 days postparturition. N-terminal sequencing of the mature M-SAA3 protein from all the three species revealed a conserved four amino acid motif (TFLK) within the first eight residues. This motif has not been reported to be present in any of the hepatically-produced acute phase SAA (A-SAA) isoforms. Cloning of the bovine M-Saa3 cDNA from mammary gland epithelial cells revealed an open reading frame that encoded a precursor protein of 131 a...
Supplemental silicon increases plasma and milk silicon concentrations in horses. The primary objective of this research was to determine the effect of supplemental dietary silicon (Si) on plasma and milk Si concentrations of lactating mares and the subsequent effect on plasma Si concentrations in nursing foals. Additionally, the role of Si on altering biochemical markers of bone turnover was investigated, because supplemental Si may be advantageous in enhancing bone health. Twelve Arabian mare/foal units were pair-matched by foaling date and randomly assigned to two groups, Si-supplemented (Supplemented) or control (Control). Blood and milk samples were taken on d 0, 15, 3...
Pregnancy-associated plasma protein-A (PAPP-A) in ovine, bovine, porcine, and equine ovarian follicles: involvement in IGF binding protein-4 proteolytic degradation and mRNA expression during follicular development. IGF binding protein-4 (IGFBP-4) proteolytic degradation is a common feature of preovulatory follicles from human, ovine, bovine, porcine, and equine ovary. In all these species, the protease is a zinc-dependent metalloprotease and its ability to degrade IGFBP-4 is IGF dependent. The human intrafollicular IGFBP-4-degrading protease has recently been identified as pregnancy-associated plasma protein-A (PAPP-A). The aim of this study was to investigate whether PAPP-A is also involved in IGFBP-4 degradation in ovine, bovine, porcine, and equine preovulatory follicles and to study the expression of...
Laparoscopic ovariectomy using sequential electrocoagulation and sharp transection of the equine mesovarium. To describe in horses and ponies a laparoscopic ovariectomy technique facilitated by electrosurgical instrumentation. Methods: Elective ovariectomy was performed in 23 mares using laparoscopic electrosurgical instrumentation. Methods: Twenty-three mares (13 horses, 10 ponies), aged from 2 to 21 years and weighing 90 to 545 kg. Methods: Food was withheld for a minimum of 12 hours. Mares were sedated with detomidine hydrochloride (0.02 to 0.03 mg/kg) or xylazine hydrochloride (0.5 to 1.0 mg/kg). Excluding the pony mares, all other mares were restrained in stocks. Portal sites in the paralumbar f...
The application of three-dimensional internal structure microscopy in the observation of mare ovary. The ovary of the mare has a unique structure which differs totally from that of other mammals. However, because of its relatively large size, conventional histological techniques were unsuitable for the observation of the internal structure of the whole ovary. Three-dimensional internal structure microscopy (3D-ISM) consists of a cryotome-CCD camera-laser disc recorder-PC-based control system coupled with a graphic workstation. The internal structure of the ovary is observed by processing over more than 1,000 stored images of serially sliced surfaces of each frozen equine ovary. The 3D reconst...
Assessment of colostral transfer and systemic availability of immunoglobulin G in new-born foals using a newly developed enzyme-linked immunosorbent assay (ELISA) system. To measure the immunoglobulin G (IgG) concentration in colostrum, milk and serum samples, a sandwich enzyme-linked immunosorbent assay (ELISA) detection system was developed. The system provided high reproducibility and sensitivity for routine diagnostic purposes. The period of fluctuating serum concentrations of IgG was monitored in new-born foals and their mares for a period of 6 weeks postnatum and postpartum, respectively. All foals received colostrum from their mares. The mean IgG concentration in the precolostral mare serum was approximately 19.0 mg/ml and decreased significantly to 13.8...
Effect of homologous preovulatory follicular fluid on in vitro maturation of equine cumulus-oocyte complexes. The objective of this study was to test the hypothesis that incubating equine cumulus-oocyte complexes (COCs) in medium containing 50% or 100% homologous preovulatory follicular fluid would improve cumulus expansion and nuclear maturation. Oocytes were incubated in one of three media: 1) supplemented TCM-199 (control), 2) 50% (v/v) follicular fluid in control medium or 3) 100% follicular fluid. Cumulus expansion was evaluated subjectively, and nuclear maturation was evaluated by staining oocytes with Hoechst 33258. The hypothesis that incubating COCs in medium containing follicular fluid would...
Penetration of zona-free hamster, bovine and equine oocytes by stallion and bull spermatozoa pretreated with equine follicular fluid, dilauroylphosphatidylcholine or calcium ionophore A23187. Experiments evaluated the ability of follicular fluid (FF), dilauroylphosphatidylcholine (PC12) and the calcium ionophore A23187 (A23187) to induce capacitation in stallion and bull spermatozoa, determined by the ability of the spermatozoa to penetrate zona-free hamster, bovine and equine oocytes. Spermatozoa suspensions were incubated at 37 degrees C in one of the following treatments: 1) a modified Tyrode's medium (BGM3) alone; 2) BGM3 + FF; 3) BGM3 + PC12; 4) BGM3 + FF + PC12; 5) BGM3 + A23187; and 6) BGM3 + FF + A23187. Treated spermatozoa were incubated with zona-free hamster, bovine and ...
Ovarian superstimulatory response and embryo production in mares treated with equine pituitary extract twice daily. Equine pituitary extract (EPE), has been reported to induce multiple ovulation in mares, however ovulation rates are poor in comparison to those obtained in other species. Attempts to improve the effectiveness of EPE for induction of superovulation in cyclic mares has focused on daily frequency of EPE treatment. Two experiments were performed to compare the ovarian response of cyclic mares given EPE once or twice-daily. Mares were assigned to one of two treatment groups 6 to 8 days after ovulation: prostaglandin was given once and EPE (25 mg) was given once daily (Group 1) or twice daily (Grou...
Failure of holmium:yttrium-aluminum-garnet laser lithotripsy in two horses with calculi in the urinary bladder. Holmium:yttrium-aluminum-garnet (Ho:YAG) laser lithotripsy was attempted in a mare and a gelding with calculi in the urinary bladder. The procedure was unsuccessful in producing adequate fragmentation of the calculi. In the gelding, pulsed dye laser lithotripsy was subsequently used to fragment the urolith. Manual removal of the urolith via the urethra was performed in the mare.
A structural and immunological study of chorionic gonadotrophin production by equine trophoblast girdle and cup cells. Equine chorionic gonadotropin (eCG) production by the fetally derived endometrial cups appears to be necessary for the establishment and maintenance of normal equine pregnancy. Starting at about the 27th day of pregnancy, an equatorial band of trophectodermal cells on the surface of the spherical conceptus forms the chorionic girdle. This girdle consists initially of flat trophectodermal epithelium which corrugates into folds as the cells proliferate. The folds are then pressed against the uterine epithelium by expansion of the conceptus. The cells on the apices of the folds become binucleate ...
The acrosomic reaction in stallion spermatozoa: inductive effect of the mare preovulatory follicular fluid. In the female genital tract, spermatozoa must undergo capacitation and acrosome reaction prior to fertilization. A number of factors may induce physiological acrosome reaction assayed in vitro. The aims of this study are to determine the inductive effect of the preovulatory follicular fluid on the sperm acrosomal status in the equine, once some characteristics of the follicular fluid during folliculogenesis had been evaluated. The spermatozoa were obtained from cauda epididymes of adult stallion. Follicular fluid was taken from mare ovarian follicles classified according to their diameter. In ...
Influence of epidermal growth factor on mammalian oocyte maturation via tyrosine-kinase pathway. Epidermal growth factor (EGF) has been reported to promote different functions in mammalian ovaries, including oocyte maturation. The aim of the present study was to establish: that EGF influences oocyte maturation in ovine and equine, that a tyrosine kinase-dependent intracellular mechanism mediates EGF effect and, that EGF-R receptor is detectable in ovarian follicles by immunohistochemistry methods. Selected ovine and equine oocytes were aspirated from 2-5 mm (ovine) or 25 mm (equine) follicles and cultured in TCM 199 for 22 (ovine) or 36 hours (equine). They are then subjected to culture w...
Reversed-phase liquid chromatographic method for estrogen determination in equine biological samples. Equine unsaturated estrogens are the main components of brand formulations indicated for hormonal replacement therapy in both hypogonadic and postmenopausal women. These hormones are produced by the fetoplacental unit during equine gestation. A method is described for the quantitative determination of equilenin (EL), equilin (EQ), 17alpha-dihydroequilin (17dEQ), and estrone (El) in the plasma of a pregnant mare. Blood samples are obtained weekly during pregnancy by jugular venipuncture using sodium ethylenediaminetetracetic as the anticoagulant. For the quantitation of these estrogens, plasma ...
Morphologic stages of the equine embryo proper on days 17 to 40 after ovulation. To describe the gross and histologic changes that develop in the equine embryo proper (ie, the portion of the embryo that becomes the fetus) from days 17 to 40 after ovulation and to compare the external features of equine embryos with those of porcine, ovine, and human embryos. Methods: 34 embryos collected from mixed-breed pony mares. Methods: External features for each embryo proper, including length, number of branchial arches, growth of appendages, face and head features, and body features, were examined, using a dissecting microscope, for embryos collected on days 17 to 40. Internal feat...
Luteal deficiency and embryo mortality in the mare. Four separate components combine to produce the progesterone and biologically active 5 alpha-reduced pregnanes needed to maintain pregnancy in the mare. The primary corpus luteum (CL) is prolonged beyond its cyclical lifespan by the down-regulation of endometrial oxytocin receptors to prevent activation of the luteolytic pathway and its waning progesterone production is supplemented from day 40 of gestation by the formation of a series of accessory CL which develop in the maternal ovaries as a result of the gonadotrophic actions of pituitary FSH and the equine chorionic gonadotrophin (eCG). Fr...
Influence of oocyte collection technique on initial chromatin configuration, meiotic competence, and male pronucleus formation after intracytoplasmic sperm injection (ICSI) of equine oocytes. 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...
