{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,3]],"date-time":"2025-11-03T23:03:59Z","timestamp":1762211039723,"version":"build-2065373602"},"reference-count":63,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2023,5,22]],"date-time":"2023-05-22T00:00:00Z","timestamp":1684713600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Animals"],"abstract":"<jats:p>The present experiment aimed at determining whether the timing of the maternal recognition of pregnancy (MRP) was specific to individual mares by determining when luteostasis, a failure to return to oestrus, reliably occurred in individuals following embryo reduction. Singleton (n = 150) and synchronous twin pregnancies (n = 9) were reduced in 10 individuals (5\u201329 reductions\/mare) at pre-determined time points within days 10 (n = 20), 11 (n = 65), 12 (n = 47), 13 (n = 12) or 14 (n = 15) of pregnancy. Prior to embryo reduction, the vesicle diameter was measured in 71% (106\/150) of the singleton pregnancies. The interovulatory interval (IOI) was recorded on 78 occasions in seven of the mares in either non-pregnant cycles (n = 37) or those in which luteolysis followed embryo reduction (n = 41). The earliest time post-ovulation at which the embryo reduction resulted in luteostasis in an individual was 252 h (mid-Day 10). Consistency in luteostasis following embryo reduction showed individual variation between mares (272\u2013344 h). Binary logistic regression analysis showed an individual mare effect (p &lt; 0.001) and an effect of the interval post-ovulation at which embryo reduction was undertaken (p &lt; 0.001). However, there was no significant effect of vesicle diameter at the time of embryo reduction (p = 0.099), nor a singleton or twin pregnancy (p = 0.993), on the dependent of luteolysis or luteostasis. The median IOI between individual mares varied significantly (p &lt; 0.05) but was not correlated to the timing of MRP. The timing of MRP varied between the mares but was repeatable in each individual. The factors and mechanisms underlying the individuality in the timing of MRP were not determined and warrant further study.<\/jats:p>","DOI":"10.3390\/ani13101718","type":"journal-article","created":{"date-parts":[[2023,5,23]],"date-time":"2023-05-23T01:36:48Z","timestamp":1684805808000},"page":"1718","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["The Timing of the Maternal Recognition of Pregnancy Is Specific to Individual Mares"],"prefix":"10.3390","volume":"13","author":[{"given":"John R.","family":"Newcombe","sequence":"first","affiliation":[{"name":"Warren House Farm, Equine Fertility Clinic, Brownhills WS8 6LU, West Midlands, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6939-017X","authenticated-orcid":false,"given":"Juan","family":"Cuervo-Arango","sequence":"additional","affiliation":[{"name":"Departamento de Medicina y Cirug\u00eda Animal, Facultad de Veterinaria, Universidad Cardenal Herrera-CEU, CEU Universities, 46115 Alfara del Patriarca, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2903-9219","authenticated-orcid":false,"given":"Sandra","family":"Wilsher","sequence":"additional","affiliation":[{"name":"Sharjah Equine Hospital, Sharjah 61313, United Arab Emirates"},{"name":"The Paul Mellon Laboratory of Equine Reproduction, \u201cBrunswick\u201d, Newmarket CB8 9BJ, Suffolk, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,5,22]]},"reference":[{"key":"ref_1","unstructured":"Wolstenholme, E.W., and O\u2019Connor, M. (1969). Foetal Autonomy, Ciba Foundation Symposium, J&A Churchill Ltd."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1186\/2049-1891-4-23","article-title":"Pregnancy recognition signalling mechanisms in ruminants and pigs","volume":"4","author":"Bazer","year":"2013","journal-title":"J. Anim. Sci. Biotech."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"251","DOI":"10.1016\/0090-6980(76)90148-9","article-title":"Concentration of prostaglandins F in the uterine venous plasma of anaesthetized mares during the oestrous cycle and early pregnancy","volume":"11","author":"Douglas","year":"1976","journal-title":"Prostaglandins"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1016\/0090-6980(78)90194-6","article-title":"Uterine luminal prostaglandin F in cycling mares","volume":"16","author":"Zavy","year":"1978","journal-title":"Prostaglandins"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"581","DOI":"10.1095\/biolreprod25.3.581","article-title":"Prostaglandin F2alpha in the equine endometrium: Steroid modulation and production capacities during the estrous cycle and early pregnancy","volume":"25","author":"Vernon","year":"1981","journal-title":"Biol. Reprod."},{"key":"ref_6","first-page":"335","article-title":"Effect of pregnancy and collection technique on prostaglandin F in the uterine lumen of pony mares","volume":"32","author":"Berglund","year":"1982","journal-title":"J. Reprod. Fert. Suppl."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"261","DOI":"10.1530\/rep.0.1230261","article-title":"Prostaglandin E(2) and F(2 alpha) production by equine conceptuses and concentrations in conceptus fluids and uterine flushings recovered from early pregnant and dioestrous mares","volume":"123","author":"Stout","year":"2002","journal-title":"Reproduction"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"45","DOI":"10.1016\/j.theriogenology.2019.04.004","article-title":"Endogenous and exogenous effects of PGF2\u03b1 during luteolysis in mares","volume":"132","author":"Ginther","year":"2019","journal-title":"Theriogenology"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"10","DOI":"10.1016\/j.theriogenology.2021.02.004","article-title":"Concentrations of progesterone and a PGF2\u03b1 metabolite during the interovulatory interval compared to the corresponding days of pregnancy in the mare","volume":"165","author":"Castro","year":"2021","journal-title":"Theriogenology"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"46","DOI":"10.1111\/j.1439-0531.2012.02023.x","article-title":"Endometrial phospholipase A2 activity during the oestrous cycle and early pregnancy in mares","volume":"48","author":"Ababneh","year":"2013","journal-title":"Reprod. Domest. Anim."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1530\/jrf.0.1090137","article-title":"Relationship between endometrial oxytocin receptors and oxytocin-induced prostaglandin F2 alpha release during the oestrous cycle and early pregnancy in pony mares","volume":"109","author":"Sharp","year":"1997","journal-title":"J. Reprod. Fertil."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"173","DOI":"10.1530\/jrf.0.1130173","article-title":"Endometrial oxytocin receptor and uterine prostaglandin secretion in mares during the oestrous cycle and early pregnancy","volume":"113","author":"Starbuck","year":"1998","journal-title":"J. Reprod. Fertil."},{"key":"ref_13","first-page":"107064","article-title":"Endometrial and luteal gene expression of putative gene regulators of equine maternal recognition of pregnancy","volume":"245","author":"Bramer","year":"2002","journal-title":"Anim. Reprod. Sci."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"102","DOI":"10.1095\/biolreprod.109.081612","article-title":"Transcriptional profiling of equine endometrium during the time of maternal recognition of pregnancy","volume":"83","author":"Klein","year":"2010","journal-title":"Biol. Reprod."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"834","DOI":"10.1071\/RD13381","article-title":"Effect of pregnancy on endometrial expression of luteolytic pathway components in the mare","volume":"27","author":"Stout","year":"2015","journal-title":"Reprod. Fertil. Dev."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"909","DOI":"10.1016\/S0093-691X(02)01362-6","article-title":"A light microscopic and ultrastructural study on the presence and location of oxytocin in the equine endometrium","volume":"60","author":"Bae","year":"2003","journal-title":"Theriogenology"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"183","DOI":"10.1016\/S0739-7240(99)00008-9","article-title":"Oxytocin-neurophysin I mRNA abundance in equine uterine endometrium","volume":"16","author":"Adams","year":"1999","journal-title":"Domest. Anim. Endocrinol."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"4616","DOI":"10.1038\/s41598-023-31540-9","article-title":"Characterization of serum and tissue oxytocinase and tissue oxytocin in the pregnant and non-pregnant mare","volume":"13","author":"Dong","year":"2023","journal-title":"Sci. Rep."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"437","DOI":"10.1530\/jrf.0.0930437","article-title":"Measurement of oxytocin concentrations in plasma and ovarian extracts during the oestrous cycle of mares","volume":"93","author":"Stevenson","year":"1991","journal-title":"J. Reprod. Fertil."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"133","DOI":"10.1016\/0739-7240(94)00015-S","article-title":"Oxytocin in mares: Lack of evidence for oxytocin production by or action on preovulatory follicles","volume":"12","author":"Stock","year":"1995","journal-title":"Domest. Anim. Endocrinol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"831","DOI":"10.1530\/jrf.0.0760831","article-title":"Ovarian oxytocin and the maternal recognition of pregnancy","volume":"76","author":"Flint","year":"1986","journal-title":"J. Reprod. Fertil."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"88","DOI":"10.1111\/j.2042-3292.2000.tb01771.x","article-title":"Embryonic loss and abnormalities of early pregnancy","volume":"12","author":"Newcombe","year":"2000","journal-title":"Equine Vet. Educ."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"214","DOI":"10.21836\/PEM20040301","article-title":"The relationship between the number, diameter, and survival of early embryonic vesicles","volume":"20","author":"Newcombe","year":"2004","journal-title":"Pferdeheilkunde"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"575","DOI":"10.1530\/REP-09-0306","article-title":"Successful transfer of day 10 horse embryos: Influence of donor-recipient asynchrony on embryo development","volume":"139","author":"Wilsher","year":"2010","journal-title":"Reproduction"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"391","DOI":"10.1095\/biolreprod.103.020800","article-title":"Expression of key prostaglandin synthases in equine endometrium during late diestrus and early pregnancy","volume":"70","author":"Boerboom","year":"2004","journal-title":"Biol. Reprod."},{"key":"ref_26","first-page":"101","article-title":"The continuum of events leading to maternal recognition of pregnancy in mares","volume":"37","author":"Sharp","year":"1989","journal-title":"J. Reprod. Fertil. Suppl."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"107002","DOI":"10.1016\/j.anireprosci.2022.107002","article-title":"The effect of embryo reduction and transfer on luteostasis in the mare","volume":"242","author":"Wilsher","year":"2022","journal-title":"Anim. Reprod. Sci."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"103989","DOI":"10.1016\/j.jevs.2022.103989","article-title":"Transfer of Day 11 ruptured embryos can prevent luteolysis in recipient mares","volume":"113","author":"Wilsher","year":"2022","journal-title":"J. Equine Vet. Sci."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"103977","DOI":"10.1016\/j.jevs.2022.103977","article-title":"The timing of the maternal recognition of pregnancy signal is specific to individual mares","volume":"113","author":"Newcombe","year":"2022","journal-title":"J. Equine Vet. Sci."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"165","DOI":"10.1007\/978-3-319-15856-3_9","article-title":"Pregnancy recognition and implantation of the conceptus in the mare","volume":"Volume 216","author":"Geisert","year":"2015","journal-title":"Regulation of Implantation and Establishment of Pregnancy in Mammals: Tribute to 45 Year Anniversary of Roger V. Short\u2019s \u201cMaternal Recognition of Pregnancy\u201d. Advances in Anatomy, Embryology and Cell Biology"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"583","DOI":"10.1530\/REP-08-0328","article-title":"Uterine influences on embryogenesis and early placentation in the horse revealed by transfer of day-10 embryos to day-3 recipient mares","volume":"137","author":"Wilsher","year":"2009","journal-title":"Reproduction"},{"key":"ref_32","unstructured":"Ginther, O.J. (1979). Reproductive Biology of the Mare: Basic and Applied Aspects, University of Wisconsin. [1st ed.]."},{"key":"ref_33","first-page":"161","article-title":"The oestrous cycle of the mare","volume":"23","author":"Hughes","year":"1975","journal-title":"J. Reprod. Fertil. Suppl."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"415","DOI":"10.1111\/j.1751-0813.1977.tb05488.x","article-title":"The oestrous cycle of the mare and its uterine control","volume":"53","author":"Hughes","year":"1977","journal-title":"Aust. Vet. J."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"883","DOI":"10.1016\/S0093-691X(03)00279-6","article-title":"Bodyweight of mares and foals, estrous cycles and plasma glucose concentration in lactating and non-lactating Lipizzaner mares","volume":"61","author":"Heidler","year":"2004","journal-title":"Theriogenology"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"1272","DOI":"10.1016\/j.theriogenology.2015.01.010","article-title":"The effect of the interval from PGF treatment to ovulation on embryo recovery and pregnancy rate in the mare","volume":"83","author":"Aguilar","year":"2015","journal-title":"Theriogenology"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1506","DOI":"10.1016\/j.theriogenology.2016.05.009","article-title":"The period of the follicular phase during which the uterus of mares shows estrus-like echotexture influences the subsequent pregnancy rate","volume":"86","author":"Newcombe","year":"2016","journal-title":"Theriogenology"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"386","DOI":"10.1111\/evj.12739","article-title":"Likelihood of pregnancy after embryo transfer is reduced in recipient mares with a short preceding oestrus","volume":"50","author":"Claes","year":"2018","journal-title":"Equine Vet. J."},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Grabowska, A., and Kozdrowski, R. (2022). Relationship between estrus endometrial edema and progesterone production in pregnant mares two weeks after ovulation. BMC Vet. Res., 18.","DOI":"10.1186\/s12917-022-03512-0"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"96","DOI":"10.1016\/j.theriogenology.2019.03.025","article-title":"Effect of the duration of estradiol priming prior to progesterone administration on endometrial gene expression in anestrous mares","volume":"131","author":"Silva","year":"2019","journal-title":"Theriogenology"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"200","DOI":"10.1292\/jvms1922.12.200","article-title":"A study of reproduction in the mare. II. The oestrous duration and oestrous cycle","volume":"12","author":"Satoh","year":"1933","journal-title":"J. Jpn. Soc. Vet. Sci."},{"key":"ref_42","first-page":"1935","article-title":"Characteristics of estrus, diestrus and ovulation in mares and effects of season and nursing","volume":"33","author":"Ginther","year":"1972","journal-title":"Am. J. Vet. Res."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"263","DOI":"10.1152\/physrev.1999.79.2.263","article-title":"Luteolysis: A neuroendocrine mediated event","volume":"79","author":"McCracken","year":"1999","journal-title":"Physiol. Rev."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"49","DOI":"10.1186\/1477-7827-2-49","article-title":"Conceptus signals for establishment and maintenance of pregnancy","volume":"2","author":"Spencer","year":"2004","journal-title":"Reprod. Biol. Endocrin."},{"key":"ref_45","first-page":"267","article-title":"Soluble oestrogen and progesterone receptors in the endometrium of the mare","volume":"44","author":"Tomanelli","year":"1991","journal-title":"J. Reprod. Fertil. Suppl."},{"key":"ref_46","first-page":"197","article-title":"Progesterone and estrogen receptor distribution in the endometrium of mares","volume":"32","author":"Watson","year":"1992","journal-title":"Theriogenology"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1530\/jrf.0.1170135","article-title":"Changes in equine endometrial oestrogen receptor \u03b1 and progesterone receptor mRNAs during the oestrous cycle, early pregnancy and after treatment with exogenous steroids","volume":"117","author":"McDowell","year":"1999","journal-title":"J. Reprod. Fertil."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"228","DOI":"10.2746\/042516400776563554","article-title":"Cyclic endometrial steroid hormone receptor expression and proliferation intensity in the mare","volume":"32","author":"Aupperle","year":"2000","journal-title":"Equine Vet. J."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"241","DOI":"10.1530\/rep.1.00596","article-title":"Temporal and spatial associations of oestrogen receptor alpha and progesterone receptor in the endometrium of cyclic and early pregnant mares","volume":"130","author":"Hartt","year":"2005","journal-title":"Reproduction"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"185","DOI":"10.1016\/j.theriogenology.2017.11.037","article-title":"Endometrial expression of estrogen and progesterone receptors in non-cyclic mares treated only with long-acting progesterone","volume":"108","author":"Maciel","year":"2018","journal-title":"Theriogenology"},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"139","DOI":"10.2527\/jas1967.261139x","article-title":"Effect of exogenous progesterone on cycle length","volume":"26","author":"Woody","year":"1967","journal-title":"J. Anim. Sci."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"85","DOI":"10.1016\/0090-6980(88)90104-9","article-title":"Effect of exogenous progesterone on prostaglandin F2\u03b1 release and the interestrous interval in the bovine","volume":"36","author":"Garrett","year":"1988","journal-title":"Prostaglandins"},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1016\/0378-4320(94)01348-P","article-title":"Dose-response relationships of exogenous progesterone shortly after ovulation on estrous cycle length, blastocyst development and fertility in sheep","volume":"38","author":"Pope","year":"1995","journal-title":"Anim. Reprod. Sci."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"952","DOI":"10.1071\/RD10294","article-title":"Maternal recognition of pregnancy in the horse: A mystery still to be solved","volume":"23","author":"Klein","year":"2011","journal-title":"Reprod. Fertil. Dev."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"S212","DOI":"10.1016\/j.domaniend.2016.03.006","article-title":"Early pregnancy in the mare: Old concepts revisited","volume":"56","author":"Klein","year":"2016","journal-title":"Domest. Anim. Endocrinol."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"349","DOI":"10.1016\/j.theriogenology.2016.04.048","article-title":"Embryo-maternal communication during the first 4 weeks of equine pregnancy","volume":"86","author":"Stout","year":"2016","journal-title":"Theriogenology"},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"139","DOI":"10.1530\/REP-20-0437","article-title":"Maternal recognition of pregnancy in the mare: Does it exist and why do we care?","volume":"161","author":"Swegen","year":"2021","journal-title":"Reproduction"},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"874","DOI":"10.1095\/biolreprod.110.085233","article-title":"Microarray analysis of equine endometrium at Days 8 and 12 of pregnancy","volume":"83","author":"Merkl","year":"2010","journal-title":"Biol. Reprod."},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"236","DOI":"10.1016\/j.theriogenology.2018.11.018","article-title":"Early luteal phase progestin concentration influences endometrial function in pregnant mares","volume":"125","author":"Beyer","year":"2019","journal-title":"Theriogenology"},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"261","DOI":"10.1016\/j.anireprosci.2008.03.019","article-title":"The equine endometrosis: New insights into the pathogenesis","volume":"111","author":"Hoffmann","year":"2009","journal-title":"Anim. Reprod. Sci."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"603","DOI":"10.1016\/0093-691X(83)90180-2","article-title":"Mobility of the early equine conceptus","volume":"19","author":"Ginther","year":"1983","journal-title":"Theriogenology"},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"83","DOI":"10.1016\/0093-691X(84)90476-X","article-title":"Intrauterine movement of the early conceptus in barren and post-partum mares","volume":"22","author":"Ginther","year":"1984","journal-title":"Theriogenology"},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"401","DOI":"10.1016\/0093-691X(84)90460-6","article-title":"Characterisation of intrauterine mobility of the early equine conceptus","volume":"22","author":"Leith","year":"1984","journal-title":"Theriogenology"}],"container-title":["Animals"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-2615\/13\/10\/1718\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T19:40:12Z","timestamp":1760125212000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-2615\/13\/10\/1718"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,5,22]]},"references-count":63,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2023,5]]}},"alternative-id":["ani13101718"],"URL":"https:\/\/doi.org\/10.3390\/ani13101718","relation":{},"ISSN":["2076-2615"],"issn-type":[{"type":"electronic","value":"2076-2615"}],"subject":[],"published":{"date-parts":[[2023,5,22]]}}}