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Vasoya D, Tzelos T, Benedictus L, Karagianni AE, Pirie S, Marr C, Oddsdóttir C, Fintl C, Connelley T. High-Resolution Genotyping of Expressed Equine MHC Reveals a Highly Complex MHC Structure. Genes (Basel) 2023; 14:1422. [PMID: 37510326 PMCID: PMC10379315 DOI: 10.3390/genes14071422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 06/29/2023] [Accepted: 07/04/2023] [Indexed: 07/30/2023] Open
Abstract
The Major Histocompatibility Complex (MHC) genes play a key role in a number of biological processes, most notably in immunological responses. The MHCI and MHCII genes incorporate a complex set of highly polymorphic and polygenic series of genes, which, due to the technical limitations of previously available technologies, have only been partially characterized in non-model but economically important species such as the horse. The advent of high-throughput sequencing platforms has provided new opportunities to develop methods to generate high-resolution sequencing data on a large scale and apply them to the analysis of complex gene sets such as the MHC. In this study, we developed and applied a MiSeq-based approach for the combined analysis of the expressed MHCI and MHCII repertoires in cohorts of Thoroughbred, Icelandic, and Norwegian Fjord Horses. The approach enabled us to generate comprehensive MHCI/II data for all of the individuals (n = 168) included in the study, identifying 152 and 117 novel MHCI and MHCII sequences, respectively. There was limited overlap in MHCI and MHCII haplotypes between the Thoroughbred and the Icelandic/Norwegian Fjord horses, showcasing the variation in MHC repertoire between genetically divergent breeds, and it can be inferred that there is much more MHC diversity in the global horse population. This study provided novel insights into the structure of the expressed equine MHC repertoire and highlighted unique features of the MHC in horses.
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Affiliation(s)
- Deepali Vasoya
- The Roslin Institute, The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Roslin EH25 9RG, UK
| | - Thomas Tzelos
- The Roslin Institute, The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Roslin EH25 9RG, UK
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik EH26 0PZ, UK
| | - Lindert Benedictus
- Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands
| | - Anna Eleonora Karagianni
- The Roslin Institute, The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Roslin EH25 9RG, UK
| | - Scott Pirie
- Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Roslin EH25 9RG, UK
| | - Celia Marr
- Rossdales Equine Hospital, Cotton End Road, Exning, Newmarket CD8 7NN, UK
| | - Charlotta Oddsdóttir
- The Institute for Experimental Pathology at Keldur, University of Iceland Keldnavegur 3, 112 Reykjavík, Iceland
| | - Constanze Fintl
- Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, P.O. Box 5003, 1432 Ås, Norway
| | - Timothy Connelley
- The Roslin Institute, The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Roslin EH25 9RG, UK
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2
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Górecka-Bruzda A, Jaworska J, Stanley CR. The Social and Reproductive Challenges Faced by Free-Roaming Horse (Equus caballus) Stallions. Animals (Basel) 2023; 13:ani13071151. [PMID: 37048406 PMCID: PMC10093049 DOI: 10.3390/ani13071151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 03/10/2023] [Accepted: 03/22/2023] [Indexed: 03/30/2023] Open
Abstract
In captivity, intact male horses, due to their sexual drive, are usually socially isolated from other horses. This lifestyle strongly contrasts with that experienced by horses living in free-roaming, feral, or semi-feral conditions, where adult stallions have several roles in their social group, with successful reproduction being their primary drive. Reproductive skew in wild populations is high; many stallions will fail to reproduce at all, while others achieve high levels of reproductive success, siring a large number of foals. Successful stallions are those with particular characteristics and abilities that facilitate harem formation and tenure, allowing them to successfully take over a harem or establish a new one, protect mares from rival stallions, employ appropriate social behaviour to maintain group cohesion, and avoid kin-mating, for example through kin recognition mechanisms. Whilst the life of free-living stallions is far from stress-free, they retain ancestral adaptations to selection pressures (such as predation and competition) exhibited by their natural environment over thousands of years. Here, we discuss the challenges faced by free-living horse stallions, the roles they play in social groups, and their resulting social needs. By understanding these pressures and how stallions react to them, we highlighted the importance of the social environment for the stallion. It is hoped that a better understanding of wild stallions’ lives will lead to their needs being more clearly met in captivity, reducing stereotypical behaviour and improving welfare.
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Affiliation(s)
- Aleksandra Górecka-Bruzda
- Department of Animal Behaviour and Welfare, Institute of Genetics and Animal Biotechnology, Polish Academy of Sciences, 05-552 Magdalenka, Poland
- Correspondence: ; Tel.: +48-22-736-71-24
| | - Joanna Jaworska
- Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, Department of Gamete and Embryo Biology, 10-243 Olsztyn, Poland
| | - Christina R. Stanley
- Animal Behaviour & Welfare Research Group, Department of Biological Sciences, University of Chester, Chester CH1 4B, UK
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3
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Hayes-Puttfarcken AL, Kemmerly C, Keane B, Solomon NG. Do olfactory cues from males with different avpr1a genotypes affect female mate choice in prairie voles, Microtus ochrogaster? Behav Processes 2020; 180:104228. [PMID: 32882344 DOI: 10.1016/j.beproc.2020.104228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 08/05/2020] [Accepted: 08/26/2020] [Indexed: 11/17/2022]
Abstract
Multiple hypotheses have been proposed to explain female mate choice and some of the mechanisms underlying these choices. Females prairie voles display social and mating preferences for males with longer avpr1a microsatellite alleles, which provide more paternal care and exhibit less interest in novel females compared to males with shorter avpr1a microsatellite alleles. The cues females use to differentiate among males with different avpr1a genotypes are unknown, so the objective of our study was to determine if females can discriminate among males with different avpr1a genotypes using only male olfactory cues. In a laboratory choice test, females simultaneously presented with soiled bedding from a male with short versus long avpr1a microsatellite alleles showed no significant difference in the total time spent investigating each type of bedding. Nor did a greater number of females spend more time investigating soiled bedding from males with short versus long avpr1a microsatellite alleles. These findings were not influenced by female estrous status or their own avpr1a genotype. Our results suggest olfactory cues alone are insufficient to explain a female's ability to discriminate between males with different avpr1a genotypes and future research should focus on different cues or a combination of cues.
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Affiliation(s)
| | | | - Brian Keane
- Department of Biological Sciences, Miami University - Hamilton, Hamilton, OH 45011, USA.
| | - Nancy G Solomon
- Department of Biology, Miami University, Oxford, OH 45056, USA.
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4
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Guarneros M, Sánchez-García O, Martínez-Gómez M, Arteaga L. The underexplored role of chemical communication in the domestic horse, Equus caballus. J Vet Behav 2020. [DOI: 10.1016/j.jveb.2020.05.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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5
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Jaworska J, Jaworski Z, Tobolski D, Siemieniuch M, Janowski T, Górecka-Bruzda A. Selection of reproductive partners in semi-feral horses (Equus caballus) is not influenced by major histocompatibility complex (MHC): A field study. Appl Anim Behav Sci 2020. [DOI: 10.1016/j.applanim.2020.104973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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6
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Embryo survival in the oviduct not significantly influenced by major histocompatibility complex social signaling in the horse. Sci Rep 2020; 10:1056. [PMID: 31974438 PMCID: PMC6978320 DOI: 10.1038/s41598-020-58056-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 12/31/2019] [Indexed: 11/08/2022] Open
Abstract
The major histocompatibility complex (MHC) influences sexual selection in various vertebrates. Recently, MHC-linked social signaling was also shown to influence female fertility in horses (Equus caballus) diagnosed 17 days after fertilization. However, it remained unclear at which stage the pregnancy was terminated. Here we test if MHC-linked cryptic female choice in horses happens during the first days of pregnancy, i.e., until shortly after embryonic entrance into the uterus and before fixation in the endometrium. We exposed estrous mares to one of several unrelated stallions, instrumentally inseminated them with semen of another stallion, and flushed the uterus 8 days later to test for the presence of embryos. In total 68 embryos could be collected from 97 experimental trials. This success rate of 70.1% was significantly different from the mean pregnancy rate of 45.7% observed 17 days after fertilization using the same experimental protocol but without embryo flushing. Embryo recovery rate was not significantly dependent on whether the mares had been socially exposed to an MHC-dissimilar or an MHC-similar stallion. These observations suggest that MHC-linked maternal strategies affect embryo survival mainly (or only) during the time of fixation in the uterus.
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Burger D, Thomas S, Aepli H, Dreyer M, Fabre G, Marti E, Sieme H, Robinson MR, Wedekind C. Major histocompatibility complex-linked social signalling affects female fertility. Proc Biol Sci 2018; 284:rspb.2017.1824. [PMID: 29212724 DOI: 10.1098/rspb.2017.1824] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 11/02/2017] [Indexed: 02/03/2023] Open
Abstract
Genes of the major histocompatibility complex (MHC) have been shown to influence social signalling and mate preferences in many species, including humans. First observations suggest that MHC signalling may also affect female fertility. To test this hypothesis, we exposed 191 female horses (Equus caballus) to either an MHC-similar or an MHC-dissimilar stimulus male around the time of ovulation and conception. A within-subject experimental design controlled for non-MHC-linked male characteristics, and instrumental insemination with semen of other males (n = 106) controlled for potential confounding effects of semen or embryo characteristics. We found that females were more likely to become pregnant if exposed to an MHC-dissimilar than to an MHC-similar male, while overall genetic distance to the stimulus males (based on microsatellite markers on 20 chromosomes) had no effect. Our results demonstrate that early pregnancy failures can be due to maternal life-history decisions (cryptic female choice) influenced by MHC-linked social signalling.
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Affiliation(s)
- D Burger
- Swiss Institute of Equine Medicine, Agroscope and University of Berne, 1580 Avenches, Switzerland
| | - S Thomas
- Swiss Institute of Equine Medicine, Agroscope and University of Berne, 1580 Avenches, Switzerland
| | - H Aepli
- Swiss Institute of Equine Medicine, Agroscope and University of Berne, 1580 Avenches, Switzerland
| | - M Dreyer
- Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland
| | - G Fabre
- Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland
| | - E Marti
- Department of Clinical Research, Vetsuisse Faculty, University of Berne, 3012 Bern, Switzerland
| | - H Sieme
- Clinic for Horses, Unit for Reproductive Medicine, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - M R Robinson
- Department of Computational Biology, Genopode, University of Lausanne, 1015 Lausanne, Switzerland
| | - C Wedekind
- Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland
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Burger D, Meuwly C, Thomas S, Sieme H, Oberthür M, Wedekind C, Meinecke-Tillmann S. Cycle-specific female preferences for visual and non-visual cues in the horse (Equus caballus). PLoS One 2018; 13:e0191845. [PMID: 29466358 PMCID: PMC5842875 DOI: 10.1371/journal.pone.0191845] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 01/12/2018] [Indexed: 11/18/2022] Open
Abstract
Although female preferences are well studied in many mammals, the possible effects of the oestrous cycle are not yet sufficiently understood. Here we investigate female preferences for visual and non-visual male traits relative to the periodically cycling of sexual proceptivity (oestrus) and inactivity (dioestrus), respectively, in the polygynous horse (Equus caballus). We individually exposed mares to stallions in four experimental situations: (i) mares in oestrus and visual contact to stallions allowed, (ii) mares in oestrus, with blinds (wooden partitions preventing visual contact but allowing for acoustic and olfactory communication), (iii) mares in dioestrus, no blinds, and (iv) mares in dioestrus, with blinds. Contact times of the mares with each stallion, defined as the cumulative amount of time a mare was in the vicinity of an individual stallion and actively searching contact, were used to rank stallions according to each mare’s preferences. We found that preferences based on visual traits differed significantly from preferences based on non-visual traits in dioestrous mares. The mares then showed a preference for older and larger males, but only if visual cues were available. In contrast, oestrous mares showed consistent preferences with or without blinds, i.e. their preferences were mainly based on non-visual traits and could not be predicted by male age or size. Stallions who were generally preferred displayed a high libido that may have positively influenced female interest or may have been a consequence of it. We conclude that the oestrous cycle has a significant influence on female preferences for visual and non-visual male traits in the horse.
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Affiliation(s)
- Dominik Burger
- Swiss Institute of Equine Medicine ISME, University of Berne, and Agroscope, Avenches, Switzerland
- * E-mail:
| | - Charles Meuwly
- Swiss Institute of Equine Medicine ISME, University of Berne, and Agroscope, Avenches, Switzerland
| | - Selina Thomas
- Swiss Institute of Equine Medicine ISME, University of Berne, and Agroscope, Avenches, Switzerland
| | - Harald Sieme
- Unit for Reproductive Medicine–Clinic for Horses, University of Veterinary Medicine Hannover, Hanover, Germany
| | - Michael Oberthür
- Institute for Reproductive Biology, University of Veterinary Medicine Hannover, Hanover, Germany
| | - Claus Wedekind
- Department of Ecology and Evolution, Biophore, University of Lausanne, Lausanne, Switzerland
| | - Sabine Meinecke-Tillmann
- Institute for Reproductive Biology, University of Veterinary Medicine Hannover, Hanover, Germany
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9
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Jeannerat E, Marti E, Berney C, Janett F, Bollwein H, Sieme H, Burger D, Wedekind C. Stallion semen quality depends on major histocompatibility complex matching to teaser mare. Mol Ecol 2018; 27:1025-1035. [PMID: 29334412 DOI: 10.1111/mec.14490] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2017] [Revised: 12/19/2017] [Accepted: 12/22/2017] [Indexed: 01/11/2023]
Abstract
The major histocompatibility complex (MHC) has repeatedly been found to influence mate choice of vertebrates, with MHC-dissimilar mates typically being preferred over MHC-similar mates. We used horses (Equus caballus) to test whether MHC matching also affects male investment into ejaculates after short exposure to a female. Semen characteristics varied much among stallions. Controlling for this variance with a full-factorial within-subject experimental design, we found that a short exposure to an MHC-dissimilar mare enhanced male plasma testosterone and led to ejaculates with elevated sperm numbers as compared to exposure to an MHC-similar mare. Sperm velocity seemed not affected by the treatment. Overall genetic similarity between stallions and mares (determined from polymorphic microsatellites on 20 different chromosomes) played no significant role here. The MHC type of the teaser mare also affected characteristics of cold-stored sperm after 24 and 48 hr. As expected from ejaculate economics, sperm viability was elevated after exposure to an MHC-dissimilar mare. However, oxidative stress and the percentage of sperm with a high DNA fragmentation were mostly increased after exposure to an MHC-dissimilar mare, depending also on whether the teaser mare was in oestrous or not. We conclude that males can quickly adjust ejaculate quality relative to a female's MHC, and that this male reaction to the social environment can also affect important characteristics of cold-stored semen.
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Affiliation(s)
- E Jeannerat
- Swiss Institute of Equine Medicine ISME, Agroscope and University of Berne, Avenches, Switzerland
| | - E Marti
- Department of Clinical Research, Vetsuisse Faculty, University of Berne, Berne, Switzerland
| | - C Berney
- Department of Ecology and Evolution, Biophore, University of Lausanne, Lausanne, Switzerland
| | - F Janett
- Clinic of Reproductive Medicine, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - H Bollwein
- Clinic of Reproductive Medicine, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - H Sieme
- Unit for Reproductive Medicine - Clinic for Horses, University of Veterinary Medicine Hannover, Hannover, Germany
| | - D Burger
- Swiss Institute of Equine Medicine ISME, Agroscope and University of Berne, Avenches, Switzerland
| | - C Wedekind
- Department of Ecology and Evolution, Biophore, University of Lausanne, Lausanne, Switzerland
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10
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Sadeghi R, Moradi-Shahrbabak M, Miraei Ashtiani SR, Miller DC, Antczak DF. MHC haplotype diversity in Persian Arabian horses determined using polymorphic microsatellites. Immunogenetics 2017; 70:305-315. [PMID: 29170799 DOI: 10.1007/s00251-017-1039-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 10/19/2017] [Indexed: 01/15/2023]
Abstract
Previous research on the equine major histocompatibility complex (MHC) demonstrated strong correlations between haplotypes defined by polymorphic intra-MHC microsatellites and haplotypes defined using classical serology. Here, we estimated MHC diversity in a sample of 124 Arabian horses from an endangered strain native to Iran (Persian Asil Arabians), using a validated 10-marker microsatellite panel. In a group of 66 horses related as parent-offspring pairs or half-sibling groups, we defined 51 MHC haplotypes, 49 of which were new. In 47 of the remaining 58 unrelated horses, we could assign one previously identified MHC haplotype, and by default, we gave provisional haplotype status to the remaining constellation of microsatellite alleles. In these horses, we found 21 haplotypes that we had previously defined and 31 provisional haplotypes, two of which had been identified in an earlier study. This gave a total of 78 new MHC haplotypes. The final 11 horses were MHC heterozygotes that we could not phase using information from any of the previously validated or provisional haplotypes. However, we could determine that these horses carried a total of 22 different undefined haplotypes. In the overall population sample, we detected three homozygous horses and one maternally inherited recombinant from 21 informative segregations. Virtually all of the horses tested were MHC heterozygotes, and most unrelated horses (98%) were heterozygous for rare microsatellite-defined haplotypes found less than three times in the sampled horses. This is evidence for a very high level of MHC haplotype variation in the Persian Asil Arabian horse.
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Affiliation(s)
- R Sadeghi
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
- Department of Animal Science, University of Tehran, Karaj, 4111, Iran
| | | | | | - D C Miller
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
| | - Douglas F Antczak
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA.
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11
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Quality of seminal fluids varies with type of stimulus at ejaculation. Sci Rep 2017; 7:44339. [PMID: 28287188 PMCID: PMC5347088 DOI: 10.1038/srep44339] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 02/07/2017] [Indexed: 02/06/2023] Open
Abstract
The theory of ejaculate economics was mainly built around different sperm competition scenarios but also predicts that investments into ejaculates depend on female fecundity. Previous tests of this prediction focused on invertebrates and lower vertebrate, and on species with high female reproductive potential. It remains unclear whether the prediction also holds for polygynous mammals with low female reproductive potential (due to low litter size and long inter-birth intervals). We used horses (Equus caballus) to experimentally test whether semen characteristics are adjusted to the oestrous cycle of the mare a stallion is exposed to during few moments before ejaculation. We analysed 122 weekly semen samples collected from 16 stallions during exposure to either an oestrous or a dioestrous mare. Semen volume and the rate of motile sperm were higher when stallions were exposed to an oestrous than to a diestrous mare, while total sperm counts and sperm velocity remained unchanged. Sperm collected after exposure to an oestrous mare also showed reduced oxidative degeneration of cell membranes over a period of 48 hours. We conclude that stallions invest more into their seminal fluids when the chance of fertilization is elevated, and that this adjustment of ejaculate quality can happen very quickly.
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