International Symposium on Equine Reproduction

International Symposium on Equine Reproduction

INTERNATIONAL SYMPOSIUM ON EQUINE REPRODUCTION The Eighth International Symposium on Equine Reproduction was held July 22-26, 2002, at Fort Collins, C...

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INTERNATIONAL SYMPOSIUM ON EQUINE REPRODUCTION The Eighth International Symposium on Equine Reproduction was held July 22-26, 2002, at Fort Collins, CO. These equine reproduction symposia are held every 4 years at various countries around the world. The first symposium in Cambridge and its International Committee were organized by Twink Allen, Peter Rossdale, and Doug Mitchell in 1974. Over the years, the symposia have been quite similar, with the purpose being to bring together researchers in the field of equine reproduction to report their latest research. Originally, neonatology was included in the symposium, but eventually a separate committee and symposia were organized for this specialty. This year’s symposium was divided into 4 topics: the stallion, the nonpregnant mare, conception and early development, and the pregnant mare and perinatology. It is impossible to cover in depth all of the research described at this symposium; therefore, this review covers only papers on the stallion. The details can be obtained from the proceedings published in a special edition of Theriogenology by Elsevier Science. Other topics will be reported later in JEVS.

The Stallion C.C. Love et al reported their efforts at computerizing spermatozoal motility analysis and the sperm chromatin structure assay to evaluate the relationship between seminal plasma level and extender type to the maintenance of sperm motility and DNA integrity. C.A. Tiplady et al described their study on the effects of adding seminal plasma to, and glass wool separation of,

Copyright 2002, Elsevier Science (USA). All rights reserved. 0737-0806/02/2210-0004$35.00/0 doi:10.1053/jevs.2002.37328

Volume 22, Number 10, 2002

stallion epididymal spermatozoa upon their prefreeze and postthaw motility and their plasma membrane integrity, with a view to improving their fertilizing capacity. I. Barrier-Battut et al provided data about Ca, Mg, Cu, and Zn concentrations in seminal plasma of fertile stallions, and their investigation of the relationship between Ca, Mg, Cu, and Zn concentrations in seminal plasma and sperm motility after freezing and thawing. R.V. Devireddy et al provided evidence that osmotic injury can affect the sperm plasma membrane permeability to water and consequently the cryopreservation of the sperm. Osmotic injury can be caused by contamination of seminal plasma samples with artificial vagina AV lubricant or cold shock injury. F.S. Zahn et al described how cholesterol incorporation into the equine spermatozoa membrane by incubation with cholesterol-methyl-␤-cyclodextrin inclusion complex causes stabilization of sperm membranes, enhancing membrane integrity postthawing, and that this stabilization decreases the fertility of frozenthawed semen as it obstructs the acrosome reaction. T. Katila et al described their studies of freezing various fractions of stallion ejaculates to compare the freezability of each fraction separately. M. Henry et al described the use of alternative cryoprotectants and combinations of cryoprotectants aiming at the improvement of postthaw sperm integrity and motility. They concluded that ethylene glycol alone or in combination with glycerol and acetamide combined with trehalose and methyl cellulose are alternative cryoprotectants to be used for freezing stallion semen. M. Vidament et al described the effects of increasing concentrations of glycerol (G) and dimethyl formamide (DMF), added separately or in combina-

tion in the freezing extender, on the motility and the fertility of equine spermatozoa. R.P. Arruda et al described the effects of extenders and cryoprotectants on stallion sperm head morphometry using commercial automated sperm morphometry analyses. Morphometric dimensions of sperm heads cryopreserved in different extenders and cryoprotectants were smaller than in fresh-extended sperm. These differences may be due to acrosomal damage or due to nuclear overcondensation. A. Marques et al described their studies to evaluate the effects of ascorbic acid, pentoxifylline and the combination of both on the progressive motility, vigor, viability, and integrity of acrosome of cryopreserved stallion spermatozoa, submitted to in vitro incubation. Both groups, pentoxifylline and ascorbic acid plus pentoxifylline, increased semen progressive motility significantly. L. Duoos et al described their studies that showed that the use of a watersoluble lubricant should be avoided and replaced with an oil based lubricant or be used with precaution when semen is collected by the use of an artificial vagina. D.P. Leme et al described their studies evaluating the influence of season on equine spermatogenic cells and Sertoli cell quantification and their nuclear diameter by testicular fine-needle aspiration cytology. A.S.L. Medeiros et al described their investigation of several kinds of amides for use in freezing equine semen. They concluded that amides protected stallion sperm from cryodamage better than glycerol. G.M. Gomes et al reported their research results that showed that 5% dimethyl-formamide (DF) and 5% methylformamide (MF) appeared to be better cryoprotectants for preserving sperm cells from cryodamage. They said DF is

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an excellent alternative for improving the spermatozoa preservation of stallions considered “bad freezers.” D.M. Neild et al described their studies aimed at determining more exactly what happens at the sperm membrane level during peroxidative stress by using a fluorescent membrane probe that fluoresces red in the intact state but green after peroxidation and, thus, specifically monitors the process of lipid peroxidation. They also compared fresh and frozen-thawed semen samples to determine whether cryopreservation makes sperm membranes more susceptible to oxidative stress. B.A. Ball et al evaluated the generation of reactive oxygen species by equine sperm, to determine the effect on normal and abnormal sperm function, to measure the activity of enzyme scavengers in seminal plasma, and to assess the effect of antioxidants on sperm storage. D.D. Varner et al reported the results of research to determine the allowable variation in a protocol for assessing functional integrity of acrosomes in stallions. This was called the acrosomal responsiveness assay. R. Rathi et al described their investigation of the role of protein kinases in progesterone-mediated induction of the acrosome reaction in stallion spermatozoa. One goal was to determine whether bicarbonate, an inducer of sperm capacitation, acts via the same pathway as progesterone, or otherwise synergizes the effects of progesterone. H. Sieme et al described their evaluation of the effects of frequency and interval of semen collection in stallions during the breeding season to investigate its influence on sperm vitality and fertility. M.L. Macpherson et al described their evaluation of the optimal formulation and processing procedures necessary to use a new discontinuous density gradient called PureSperm. Discontinu-

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ous density gradients have been used to select populations of higher quality sperm for assisted reproductive techniques in humans. K.M. Wendt et al described their attempts to create a model to describe the change in sperm motion characteristics due to variation in extender pH and to determine if any changes in motion characteristics are consistent with the hyperactivated motility state of a typical capacitated sperm. A.C.P. Cottorello et al described the effect of 3 storage temperatures on the longevity of cooled extended donkey semen. C. Serres et al reported the effect of the elimination of the seminal plasma via centrifugation and the effect of storage temperature on the motility and plasma membrane integrity of semen of Zamorano-Leones jackasses. L.E. Limone et al reported on the effects of commonly used lubricants on longevity of stallion sperm motion measures during cooled storage. E. Koskinen et al described their study of fractionated stallion ejaculates to determine catalase and total protein concentrations in different fractions of the ejaculate. The study was prompted by another study reporting that catalase activity could be used as a marker for prostate contribution during ejaculation. B. Colenbrander et al reported the characterization of the lipids contained within the plasma membrane of equine sperm and to examine how their distribution is altered by bicarbonate-induced capacitation. G. Stradaioli and M. Magistrini described their study designed to compare the direct fluorometric evaluation of thiobarbituric acid reactive substances with the reverse phase -performance liquid chromatography procedure for isolation and measurement of the malondialdehyde-thiobarbituric acid complex in equine semen. They also described the efficacy of the 2 methods in recovering malondialdehyde from some extenders commonly used for equine semen preservation. A.C. Pommer et al reported their

study of the use of tyrosine phosphorylation as an indicator of capacitation status in fresh and cryopreserved stallion spermatozoa. J.J. Linfor et al reported that osmotic stress induces tyrosine phosphorylation of equine sperm. K.R. Breazeale et al reported that detection and initial characterization of equine zonadhesin, with an emphasis on properties that may vary with fertility of different stallions. J.P. Kayser et al described their studies that attempted to (1) characterize the de novo protein synthesis by equine uterine explants during short-term coculture in the presence or absence of sperm and (2) to investigate interactions between uterine proteins and spermatozoa. C. Staub et al described their study to determine if apoptosis occurs at higher rates during specific steps of seminiferous tubule development. Using the unique pattern of seminiferous tubule development in the stallion, a new classification scheme was developed based on lumen score and seminiferous epithelial differentiation. N. Heninger et al described their study to (1) determine if apoptosis or programmed germ cell death occurred in adult stallions with normal testes and (2) describe apoptotic rates by stage of the seminiferous epithelial cycle in stallion testes in which apoptosis of germ cells occurred. C. Donnelly et al evaluated the ability of various growth factors and estradiol, alone or in combination, to prevent apoptosis of germ cells in short-term equine testicular cultures. T.A. Stein et al described their study of stallions treated with Letrozole and evaluated for changes in hormone profiles and sperm production. J.M. Parlevliet et al described their study of age-related changes of testosterone and estradiol-17␤ in various sections of the epididymus compared with that in the testis. T.H. Welsh Jr et al described the effect of ponazuril treatment on steroidogenic function of the stallion testis.

JOURNAL OF EQUINE VETERINARY SCIENCE

J.E. Aurich et al described their study of various semen parameter values in the draught horse breed, the Austrian Noriker. K. Stich et al described the influence of testicular size on the number of consecutive days of semen collection required to stabilize the number of sperm in ejaculates of sexually mature stallions. A.N. James et al described their study designed to identify a window of opportunity to collect equine epididymal sperm for subsequent fertilization. J.E. Bruemmer et al reported their study of the effects of storing epididymal stallion semen in situ at 5°C for 24 hours before cryopreservation. M.F. Hess et al described their attempts to immunolocalize the cytochrome P450arom enzyme within the testicular cells of prepubertal, pubertal colts, and postpubertal colts and stallions by using immunocytochemical and cell culture techniques.

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A.M. Laughlin et al described their evaluation of those genes that are differentially expressed during spermatogenesis to enable researchers and clinicians to better understand the causes of reduced fertility in stallions. R. Jude et al reported their investigation of the equine CRISP1 gene and its variability in the Hanoverian horse population. They discussed the possibility of associations between different CRISP1 genotypes and the reproductive performance in stallions. R.M. Turner and R. Casas-Dolz described their attempts to determine which, if any, genes are differentially expressed in testicles from stallions with advanced idiopathic testicular degeneration. G. Fortier et al described their study designed to determine the effect of GnRH antagonist on testosterone secretion, spermatogenesis, and excretion of Equine Viral Arteritis virus in semen of stallions that are permanent carrier of the virus.

C. Aurich et al described the involvement of growth hormone in the regulation of testicular function in the pony stallion. W.A. Storer et al described their study to determine if a growth hormone treatment during the nonbreeding season would enhance the testosterone response of the stallion testis to exogenous lutinizing hormone. M.A. Pozor and S.M. McDonnell described their use of Doppler ultrasonography to characterize blood flow to the stallion testicle. Abstracts of these presentations are published in Equine Reproduction VIII, edited by Margaret J. Evans, published by Elsevier Science, as a special issue of Theriogenology.

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