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Topic:Reproduction

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.
Plasma activin A concentrations during late gestation in Thoroughbred mares with abnormal pregnancies.
Journal of equine veterinary science    December 2, 2022   Volume 120 104184 doi: 10.1016/j.jevs.2022.104184
Tsogtgerel M, Murase H, Moriyama H, Sato F, Nambo Y.Late-term fetal loss in horses is a major problem in the horse-breeding industry globally. Abnormal pregnancies should be diagnosed as early as possible to prevent abortions and other gestational problems. According to our previous longitudinal study in healthy pregnant mares, the plasma activin A concentration increases as pregnancy progresses. The aim of the present study was to compare plasma activin A concentrations in healthy pregnant Thoroughbred mares (n=40) with those in pregnant mares that suffered fetal loss or showed abnormal symptoms (n=30) during late gestation. This field study f...
Early embryonic death in equines and camelids.
Open veterinary journal    December 1, 2022   Volume 12, Issue 6 903-909 doi: 10.5455/OVJ.2022.v12.i6.16
Ashraf R, Rashid S, Rasheed I, Asif S.This paper includes the study of early embryonic death (EED), predisposing factors of EED and treatment. EED refers to the fetal mortality which varies in mare and camelids but most probably not later than 50 days of gestation. This duration may be divided into very early mortality, early mortality and late embryonic mortality. This also varies in mare and camelids. There are different embryonic, maternal, environmental/external, and infectious and noninfectious factors which lead to early embryonic loss. Diagnosis is very difficult as in most of the cases resorption of fetus occurs but it is ...
An Investigation of Equine Sperm Quality Following Cryopreservation at Low Sperm Concentration and Repeated Freeze-Thawing.
Journal of equine veterinary science    December 1, 2022   Volume 120 104167 doi: 10.1016/j.jevs.2022.104167
Morse-Wolfe B, Bleach E, Kershaw C.Stallion spermatozoa are typically cryopreserved at 200 to 300 million sperm/ml; however recent advances such as intracytoplasmic sperm injection (ICSI) requires only one spermatozoon, wasting many, after thawing a whole straw. Cryopreserving at concentrations less than the current standard or refreezing thawed spermatozoa could maximize the use of genetically valuable animals and reduce waste. This investigation aimed to identify if lowering the sperm concentration for cryopreservation affected post-thaw quality after one and two freeze-thaw cycles. Nine ejaculates were collected from three f...
Populations of NK Cells and Regulatory T Cells in the Endometrium of Cycling Mares-A Preliminary Study.
Animals : an open access journal from MDPI    November 30, 2022   Volume 12, Issue 23 3373 doi: 10.3390/ani12233373
Jaworska J, de Mestre AM, Wiśniewska J, Wagner B, Nowicki A, Kowalczyk-Zięba I, Wocławek-Potocka I.Endometrial immune cells are essential to support uterine functions across the estrous cycle and in preparation for pregnancy. It has been acknowledged that changes in phenotype and/or numbers of lymphocytes, such as regulatory T cells (Tregs) and NK cells, might result in lower fertility in women and mice. Little is known about equine endometrial immune cells across the estrous cycle. Here, we compared the populations of endometrial Tregs and NK cells in estrus and diestrus in mares. Endometrial biopsy and blood samples were taken in estrus and diestrus from 11 mares ages 4-12 years. Flow cyt...
Effect of different concentrations of Trolox® in association with docosahexaenoic acid on equine semen freezing.
Animal reproduction    November 28, 2022   Volume 19, Issue 4 e20220010 doi: 10.1590/1984-3143-AR2022-0010
Aguiar CS, Barros CHSC, Machado WM, Allaman IB, Leite AO, Barbosa LP, Snoeck PPDN.The aim of this study was to evaluate the association of different concentrations of Trolox and the addition of a fixed concentration of DHA in the freezing of semen of Mangalarga Marchador stallions. To that end, 16 ejaculates were frozen in the following extenders: E1) BotuCrio (BC; Control); E2) BC + 50 ngml DHA + 30 µM Trolox (BCDHA30T); E3) BC + 50 ngml DHA + 40 µM Trolox (BCDHA40T); E4) BC + 50 ngml DHA + 50 µM Trolox (BCDHA50T). All the tested extenders were similar in preserving different kinematic parameters, cell functional integrity, compacted DNA, and high and intermediate mitoc...
Major locus on ECA18 influences effectiveness of GonaCon vaccine in feral horses.
Journal of reproductive immunology    November 28, 2022   Volume 155 103779 doi: 10.1016/j.jri.2022.103779
Thompson MA, McCann BE, Simmons RB, Rhen T.Contraceptive vaccines are used to reduce birth rates in wild and feral animal populations. While the immunocontraceptive GonaCon-Equine has proven effective in reducing fertility among female feral horses, there is individual variation in the duration of infertility following treatment. To identify genetic factors influencing the effectiveness of GonaCon-Equine, we conducted a genome-wide association study of 88 mares from a feral population genotyped using the Illumina GGP Equine 70k SNP array. Contraceptive treatment schedules and long-term foaling rates have been recorded for each individu...
The effect of dexamethasone and flunixin-meglumine on ovulation, endometrial oedema, and inter-ovulatory interval length in the mare.
Theriogenology    November 28, 2022   Volume 197 57-61 doi: 10.1016/j.theriogenology.2022.11.042
Martínez-Boví R, Plaza-Dávila M, Cuervo-Arango J.The use of flunixin-meglumine (a potent non-steroidal anti-inflammatory drug) during the critical period of intrafollicular prostaglandin production before ovulation (24 and 36 h after hCG treatment) results in a high rate of ovulatory failure and formation of haemorrhagic anovulatory follicles (HAF) in the mare. Dexamethasone is commonly used to prevent persistent mating-induced endometritis in susceptible mares, but the effect on ovulation blockage within the pre-ovulatory critical window of intrafollicular prostaglandins production following hCG administration has not been determined. Six ...
Penicillin and amikacin mixture has bactericidal activity equivalent to gentamicin, tylosin, lincomycin and spectinomycin mixture in equine frozen semen.
Reproduction in domestic animals = Zuchthygiene    November 25, 2022   Volume 58, Issue 2 349-357 doi: 10.1111/rda.14294
Brito LFC, Loomis PR, Klohonatz KM, Althouse GC.Neat stallion semen can contain a variety of microorganisms, some of which may impair sperm quality and/or cause infection of the mares' reproductive tract. For this reason, antibiotics are commonly added to semen extenders. A combination of gentamicin, tylosin, lincomycin and spectinomycin (GTLS) has been recommended for use, but there are no reports on the use of this mixture in equine semen extender. Penicillin and amikacin (PA) are safe for preserving sperm quality while effectively controlling bacterial growth in equine cooled stored semen, but data on frozen semen are scarce. Therefore, ...
First report and molecular characterization of cases of natural Taylorella asinigenitalis infection in three donkey breeds in Spain.
Veterinary microbiology    November 24, 2022   Volume 276 109604 doi: 10.1016/j.vetmic.2022.109604
Dorrego A, Herranz C, Pérez-Sancho M, Camino E, Gómez-Arrones V, Carrasco JJ, De Gabriel-Pérez J, Serres C, Cruz-López F.Taylorella asinigenitalis is a non-pathogenic bacteria isolated from the genital tract of donkeys but also a cause of metritis and vaginal discharge in mares. It is closely related to Taylorella equigenitalis, the cause of Contagious Equine Metritis (CEM) in horses, and has been present in different countries in Europe since 1995. Up to date, there are no studies on the prevalence of T. asinigenitalis in the equine or asinine populations in Spain; this is the first report of the presence of T. asinigenitalis in donkeys (Equus asinus) from different breeds in three regions of Spain. A total of ...
Regional antibiotic perfusion through the lateral saphenous vein in two horses with septic calcaneal osteitis.
The Journal of veterinary medical science    November 23, 2022   Volume 85, Issue 1 55-61 doi: 10.1292/jvms.22-0377
Mizuguchi Y, Kato A, Aizu M.In this case report, two horses with chronic refractory infections in the tuber calcanei were successfully managed via intravenous antibiotic regional limb perfusion through the lateral saphenous vein after failure of conventional treatment approaches, including surgery and intravenous regional limb perfusion using the cranial branch of the medial saphenous vein. Surgical delay in these cases may have allowed the development of chronic infection, which prevented the conventional regional perfusion from working effectively. The spatial difference of the vessels relative to the tuber calcanei po...
Action of swim-up and caffeine on equine frozen sperm.
Animal reproduction    November 21, 2022   Volume 19, Issue 4 e20220056 doi: 10.1590/1984-3143-AR2022-0056
Alves NC, Diniz SA, Viegas RN, Arigoni AL, Freitas MM, Lana ÂQ, Lagares MA.Cryopreservation of equine semen is crucial to semen commercialization. However, it reduces sperm motility and longevity. Thus, sperm selection methods and addition of motility-activating substances to sperm, such as caffeine, may improve sperm quality of equine frozen semen. The objective of the current work was to evaluate the effects of caffeine on recovery and quality parameters of frozen-thawed sperm subjected to swim-up selection to be used in intracytoplasmic sperm injection (ICSI) in assisted reproductive techniques. Stallion semen were frozen and after thawing different caffeine conce...
Relationship between estrus endometrial edema and progesterone production in pregnant mares two weeks after ovulation.
BMC veterinary research    November 21, 2022   Volume 18, Issue 1 414 doi: 10.1186/s12917-022-03512-0
Grabowska A, Kozdrowski R.Progesterone plays a crucial role in the maintenance of pregnancy from conception to about 100-120 days of gestation when placenta becomes the main source of gestagens. The aim of the study was to test progesterone concentration 14 days after ovulation in pregnant mares and relate it to peak estral endometrial edema and the presence of intrauterine fluid (IUF) after artificial insemination (AI), the number of treatments against IUF, and the time from AI to the day when the uterus was found free of fluid. Results: Mares were divided into two groups: group A (n = 13; age 10.8 ± 4.5 y...
OXIDATIVE STRESS AND REPRODUCTIVE FUNCTION: Oxidative stress and the long-term storage of horse spermatozoa.
Reproduction (Cambridge, England)    November 18, 2022   Volume 164, Issue 6 F135-F144 doi: 10.1530/REP-22-0264
Peña FJ, Gibb Z.The growing understanding of the mechanisms regulating redox homeostasis in the stallion spermatozoa, together with its interactions with energetic metabolism, is providing new clues applicable to the improvement of sperm conservation in horses. Based on this knowledge, new extenders, adapted to the biology of the stallion spermatozoa, are expected to be developed in the near future. The preservation of semen either by refrigeration or cryopreservation is a principal component of most animal breeding industries. Although this procedure has been successful in many species, in others, substantia...
An updated insight on testicular hemodynamics: Environmental, physiological, and technical perspectives in farm and companion animals.
Veterinary research communications    November 18, 2022   Volume 47, Issue 2 323-345 doi: 10.1007/s11259-022-10022-9
Samir H, ElSayed MI, Radwan F, Hedia M, Hendawy H, Hendawy AO, Elbadawy M, Watanabe G.In all organs, control of blood flow is important but might be particularly critical for testicular functions. This is because of the very low oxygen concentration and high metabolic rate of the seminiferous tubules, the physiological temperature of the testis, and its location outside the abdominal cavity. Many factors affect the characteristics of TBF in farm and companion animals, such as environment (thermal and seasonal effects) and physiological (species, breeds, age, body weight, and sexual maturity). Thermal environment stress has detrimental effects on spermatogenesis and consequently...
The stallion sperm acrosome: Considerations from a research and clinical perspective.
Theriogenology    November 14, 2022   Volume 196 121-149 doi: 10.1016/j.theriogenology.2022.11.012
Hernández-Avilés C, Ramírez-Agámez L, Varner DD, Love CC.During the fertilization process, the interaction between the sperm and the oocyte is mediated by a process known as acrosomal exocytosis (AE). Although the role of the sperm acrosome on fertilization has been studied extensively over the last 70 years, little is known about the molecular mechanisms that govern acrosomal function, particularly in species other than mice or humans. Even though subfertility due to acrosomal dysfunction is less common in large animals than in humans, the evaluation of sperm acrosomal function should be considered not only as a complementary but a routine test whe...
Fetal maceration in a Stationbred mare.
New Zealand veterinary journal    November 13, 2022   Volume 71, Issue 1 49-52 doi: 10.1080/00480169.2022.2134227
Heil BA, Spatholz C, Hoogenboom A, Bishop R.No abstract available
Predictors of foaling outcomes in barren and maiden Thoroughbred mares in South Africa.
Journal of the South African Veterinary Association    November 8, 2022   Volume 93, Issue 2 doi: 10.36303/JSAVA.519
Scholtz M, Guthrie AJ, Fosgate GT, Schulman ML.Population demographics and reproductive performance of Thoroughbred populations have been described, but the most recent assessment of the South African Thoroughbred population was reported two decades ago. Objectives of this study were to report demographic data for selected Thoroughbred breeding populations and to analyse selected mare-level variables in association with foaling outcomes, as predictors of reproductive performance. The National Horseracing Authority of Southern Africa's stud health scheme requires annual screening of Thoroughbred stallions, maiden and barren mares for venere...
Vaginal Bacteria in Mares and the Occurrence of Antimicrobial Resistance.
Microorganisms    November 8, 2022   Volume 10, Issue 11 2204 doi: 10.3390/microorganisms10112204
Malaluang P, Wilén E, Frosth S, Lindahl J, Hansson I, Morrell JM.Antibiotics are added to semen extenders in insemination doses but their effect on the vaginal microbiota of the inseminated female is unknown. The objectives of this study were to define the equine vaginal microbiota and its antimicrobial resistance, and to determine whether it changes after exposure to antibiotics in semen extenders. Vaginal swabs were taken prior to sham-insemination (day 0), and again on days 3, 7, and 14 after insemination. Isolated bacteria were identified by MALDI-TOF and tested for antimicrobial susceptibility by microdilution. The bacteria isolated from the vagina dif...
Low plasma progesterone concentration during the early luteal phase delays endometrial development and the beginning of placentation in mares.
Animal reproduction science    November 8, 2022   Volume 247 107149 doi: 10.1016/j.anireprosci.2022.107149
Okada CTC, Kaps M, Reichart U, Walter I, Gautier C, Aurich J, Aurich C.While detrimental effects of reduced plasma progesterone concentration in the early luteal phase on conceptus development in horses have recently been demonstrated, there is no information on associated effects on the endometrium, allantochorion (AC), and chorionic girdle (CG) in this species. We hypothesised that reduced early postovulatory progesterone concentration in pregnant horses is detrimental to endometrial function and development of the embryonic membranes and is an underlying cause of delayed conceptus development. After insemination and ovulation, mares (n = 11) were assigned to...
Characterization of microbial communities and predicted metabolic pathways in the uterus of healthy mares.
Open veterinary journal    November 7, 2022   Volume 12, Issue 6 797-805 doi: 10.5455/OVJ.2022.v12.i6.3
Thomson P, Pareja J, Núñez A, Santibáñez R, Castro R.Culture-independent techniques have made it possible to expand the knowledge about the composition of bacterial communities present in the healthy uterus and their role in health and disease, mainly in humans. However, in animals like mares, there is a dearth of information regarding this area. To narrow this knowledge gap, the objective of this study was to identify and characterize the composition and function of the uterine microbiome of a group of Chilean purebred mares (CPM), an equine breed with the oldest genealogical record in South America and an economical important reproductive indu...
Molecular surveillance of equine parvovirus-hepatitis from oral, nasal, vaginal, and semen specimens collected from horses living in Korea.
Transboundary and emerging diseases    November 7, 2022   Volume 69, Issue 6 e3455-e3461 doi: 10.1111/tbed.14746
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/...
Welfare concerns on production of pregnant mare serum gonadotropin – A comment.
The Canadian veterinary journal = La revue veterinaire canadienne    November 4, 2022   Volume 63, Issue 11 1089 
Grant C.No abstract available
Kallikrein proteoforms and reproductive parameters in stallion are conditioned by climate.
Scientific reports    November 4, 2022   Volume 12, Issue 1 18690 doi: 10.1038/s41598-022-21350-w
Senra RL, Ramírez-López CJ, Magalhães-Júnior MJ, Neves JGDS, Barros E, Waddington B, Guimarães SEF, Guimarães JD, Baracat-Pereira MC.Horses are seasonal polyoestrous animals, and the photoperiod is the main factor modulating their reproductive activity. There is no consensus on the andrological and biochemical factors that influence breeding seasonality. To assess the involvement of climate in reproduction, Mangalarga Marchador stallions were monitored over 1 year regarding semen quality and seminal plasma proteome. Here, we show that kallikrein (KLKs) proteoforms in seminal plasma are involved in climate conditioning of reproduction. During the breeding season, greater abundance and different types of KLKs occurred simult...
Metabolic profiling of preovulatory follicular fluid in jennies.
Research in veterinary science    November 3, 2022   Volume 153 127-136 doi: 10.1016/j.rvsc.2022.10.026
Catalán J, Martínez-Rodero I, Yánez-Ortiz I, Mateo-Otero Y, Bragulat AF, Nolis P, Carluccio A, Yeste M, Miró J.Follicular fluid is formed from the transudation of theca and granulosa cells in the growing follicular antrum. Its main function is to provide an optimal intrafollicular microenvironment to modulate oocyte maturation. The aim of this study was to determine the metabolomic profile of preovulatory follicular fluid (PFF) in jennies. For this purpose, PFF was collected from 10 follicles of five jennies in heat. Then, PFF samples were analysed by nuclear magnetic resonance (NMR) and heteronuclear single quantum correlation (2D H/C HSQC). Our study revealed the presence of at least 27 metabolites i...
Time-lapse imaging and developmental competence of donkey eggs after ICSI: Effect of preovulatory follicular fluid during oocyte in vitro maturation.
Theriogenology    November 1, 2022   Volume 195 199-208 doi: 10.1016/j.theriogenology.2022.10.030
Flores Bragulat AP, Ortiz I, Catalán J, Dorado J, Hidalgo M, Losinno L, Dordas-Perpinyà M, Yánez-Ortiz I, Martínez-Rodero I, Miró J, Gambini A.Equus members exhibit very divergent karyotype, genetic plasticity, and significant differences in their reproductive physiology. Despite the fact that somatic cell nuclear transfer and intracytoplasmic sperm injection (ICSI) has gained relevance in the last few years in horses, few reports have been published exploring ovum pick up (OPU) and in vitro maturation (IVM) of cumulus-oocyte complexes (COCs) in donkeys. Yet, some donkey species and breeds are considered endangered, and these assisted-reproductive technologies could help to preserve the genetic of valuable individuals. In this study...
Multivariable analysis to determine risk factors associated with abortion in mares.
Reproduction & fertility    November 1, 2022   Volume 3, Issue 4 301-312 doi: 10.1530/RAF-22-0087
Roach J, Arango Sabogal JC, Smith K, Foote A, Verheyen K, de Mestre AM.Risk factors associated with equine reproductive efficiency have been identified along with those associated specifically with early pregnancy loss (EPL). In contrast, no studies have reported risk factors associated with abortion (loss between day 70 and 300 post-cover). Given the causes of abortion differ to those of EPL, likely too will the risk factors. A retrospective cohort study was carried out to identify risk factors associated with abortion in UK and Irish based Thoroughbreds, collecting data on 20 exposure variables over a five-year period. A generalized linear mixed model was utili...
Equine Stomach Development in the Fetal Period: An Anatomical, Topographical, and Morphometric Study.
Animals : an open access journal from MDPI    October 28, 2022   Volume 12, Issue 21 2966 doi: 10.3390/ani12212966
Poradowski D, Chrószcz A.Studies of equine stomach prenatal development are very rare, and descriptions usually focus on the processes taking place in the embryonic period. Only general information about gastric organogenesis in the fetal period is available in embryology textbooks on domestic mammals. The material for our study included twenty half-breed horse fetuses divided into three age groups on the basis of known fetal age (verified using the CRL method). Our study consists of the topographical, morphological, and morphometrical description of stomach development between the 4th and 11th months of gestation. Ev...
First Description of Fetal Cystic Hygroma Associated With Early Equine Pregnancy Loss.
Journal of equine veterinary science    October 28, 2022   Volume 119 104148 doi: 10.1016/j.jevs.2022.104148
Martinez Zuviria S, Ciurkiewicz M, Wohlsein P, Madariaga G, Zuccolilli G.Cystic hygroma (hygroma cysticum) is a malformation that has not yet been described as a cause of early pregnancy loss in equines. The condition is a congenital anomaly occurring during embryogenesis due to a failure in which the primitive lymphatic sac does not reach the venous system at the jugular vein, resulting in a lymphatic stasis that starts in the neck region and continues to the rest of the body. From 2015 to 2020, a total of 5,730 ultrasound examinations were performed in mares from 43 different horse farms and embryo transfer farms when sexing pregnancies. In 12 pregnant mares, a s...
Postnatal Dynamics of Circulating Steroid Hormones in Mule and Equine Neonates.
Veterinary sciences    October 28, 2022   Volume 9, Issue 11 598 doi: 10.3390/vetsci9110598
Boakari YL, Legacki E, Alonso MA, Dos Santos ACF, Nichi M, Conley AJ, Fernandes CB.It is necessary to study hormonal patterns from mules to recognize alterations and neonatal maladaptation. Our objective was to evaluate concentrations of hormones in mule (n = 6) and equine foals (n = 6). Blood was collected at T0, 1, 6 and 12 h after birth. Hormone concentrations were evaluated using liquid chromatography tandem mass spectrometry. Effects of time, group and interactions and regression analysis were evaluated (p < 0.05). There was a cubic and quadratic decline in mule and equine foals, respectively, for 3β,20α-dihydroxy-DHP. Mule foals were born with lower circulating 3...
Not just for males: Flehmen as a tool for detection of reproductive status and individual recognition across sexes in four African equid species.
Behavioural processes    October 26, 2022   Volume 203 104773 doi: 10.1016/j.beproc.2022.104773
Pluháček J, Tučková V, King SRB.Flehmen is frequently explained as part of male sexual behaviour, but it can also be associated with overmarking behaviour and thus individual recognition. We tested three explanatory hypotheses of flehmen behaviour: to detect sexual status of a female, to decide whether to overmark an individual, and to improve individual recognition. Additionally, we examined interspecific flehmen differences in the African equids. We observed 130 individuals of all 4 species among 15 groups in 5 zoos. We recorded 4445 eliminations: 142 were accompanied by flehmen and 1648 were inspected by another animal an...
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