{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,5]],"date-time":"2026-10-05T19:15:59Z","timestamp":1791227759930,"version":"4.1.0"},"reference-count":68,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2025,4,5]],"date-time":"2025-04-05T00:00:00Z","timestamp":1743811200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Veterinary Sciences"],"abstract":"<jats:p>The aim of this investigation was to measure the natural nocturnal plasma melatonin concentration in gestating and fresh ewes. Studies in humans showed that maternal melatonin had a significant increase as pregnancy progressed and then decreased after birth. Two studies conducted in sheep so far, considering the entire gestation, have led to conflicting results. The breed of 16 pregnant ewes selected for the research was the Tsigai. Blood samples were taken into EDTA vacutainers predetermined times a night at different stages of their gestation. The RIA method was used to determine the melatonin concentrations. For estimation of its variations during gestation, population genetic statistics was applied. It was found that the average plasma melatonin concentration of 134 pg mL\u22121 is characteristic for the investigated period, and that it rises between the autumnal equinox and the winter solstice. Secondly, it was revealed that the average melatonin concentration adjusted for midnight is 162.4 pg mL\u22121, and its moderate variation is characteristic for the night. The investigation showed that there is no connection between the plasma melatonin concentration of the ewes and their gestational age in the Tsigai breed in Middle Europe. Our result is consistent with the results of single studies in sheep and donkey, in contrast to human observations. With regard to the nocturnal plasma melatonin, the concentration is reduced at the same level (30 pg mL\u22121) in ewes and lambs during the early postpartum period without nightly fluctuation. The expelled placenta, the constant vigilance between the mother and her lamb, and the opposition between melatonin and prolactin may provide a plausible explanation for this.<\/jats:p>","DOI":"10.3390\/vetsci12040336","type":"journal-article","created":{"date-parts":[[2025,4,23]],"date-time":"2025-04-23T20:43:17Z","timestamp":1745440997000},"page":"336","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Determination of Natural Blood Plasma Melatonin Concentration of Tsigai Ewes Characteristic for Gestation and Early Postpartum Period Between Autumnal Equinox and Winter Solstice"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3805-507X","authenticated-orcid":false,"given":"Andr\u00e1s","family":"G\u00e1sp\u00e1rdy","sequence":"first","affiliation":[{"name":"Institute for Animal Breeding, Nutrition and Laboratory Animal Science, University of Veterinary Medicine Budapest, 1078 Budapest, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"L\u00e1szl\u00f3","family":"Guly\u00e1s","sequence":"additional","affiliation":[{"name":"Department of Animal Sciences, Faculty of Agriculture and Food Sciences, Sz\u00e9chenyi Istv\u00e1n University, 9200 Mosonmagyar\u00f3v\u00e1r, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ida","family":"Polland","sequence":"additional","affiliation":[{"name":"Veterin\u00e6r Ida Marie Polland AS, 3330 Skotselv, Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Al\u00e1n","family":"Alp\u00e1r","sequence":"additional","affiliation":[{"name":"Department of Anatomy, Histology and Embryology, Semmelweis University, 1094 Budapest, Hungary"},{"name":"SE NAP Research Group of Experimental Neuroanatomy and Developmental Biology, Semmelweis University, 1094 Budapest, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6907-6626","authenticated-orcid":false,"given":"S\u00e1ndor Gy\u00f6rgy","family":"Fekete","sequence":"additional","affiliation":[{"name":"Institute for Animal Breeding, Nutrition and Laboratory Animal Science, University of Veterinary Medicine Budapest, 1078 Budapest, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Levente","family":"Harmat","sequence":"additional","affiliation":[{"name":"Experimental Farm, University of Veterinary Medicine Budapest, 2225 \u00dcll\u0151, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,4,5]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2587","DOI":"10.1021\/ja01543a060","article-title":"Isolation of melatonin, the pineal gland factor that lightens melanocytes1","volume":"80","author":"Lerner","year":"1958","journal-title":"J. Am. Chem. Soc."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1016\/0301-6226(81)90030-0","article-title":"Natural factors affecting puberty and reproductive performance in ewe lambs: A review","volume":"8","year":"1981","journal-title":"Livest. Prod. Sci."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"335","DOI":"10.1016\/j.pneurobio.2008.04.001","article-title":"Physiological effects of melatonin: Role of melatonin receptors and signal transduction pathways","volume":"85","author":"Trakht","year":"2008","journal-title":"Prog. Neurobiol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"190","DOI":"10.1016\/j.physbeh.2006.09.010","article-title":"Circadian control of the sleep\u2013wake cycle","volume":"90","author":"Beersma","year":"2007","journal-title":"Physiol. Behav."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Basini, G., and Grasselli, F. (2024). Role of Melatonin in Ovarian Function. Animals, 14.","DOI":"10.3390\/ani14040644"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"175","DOI":"10.1016\/S1087-0792(98)90020-X","article-title":"Basic aspects of melatonin action","volume":"2","author":"Cardinali","year":"1998","journal-title":"Sleep Med. Rev."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Zhao, D., Yu, Y., Shen, Y., Liu, Q., Zhao, Z., Sharma, R., and Reiter, R.J. (2019). Melatonin Synthesis and Function: Evolutionary History in Animals and Plants. Front. Endocrinol., 10.","DOI":"10.3389\/fendo.2019.00249"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"259","DOI":"10.1016\/j.anireprosci.2011.02.024","article-title":"Reproductive cycles in sheep","volume":"124","author":"Bartlewski","year":"2011","journal-title":"Anim. Reprod. Sci."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"586","DOI":"10.1080\/09291016.2018.1548112","article-title":"Physiology of reproductive seasonality in sheep\u2014An update","volume":"51","author":"Aarif","year":"2020","journal-title":"Biol. Rhythm Res."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Watson, R.R. (2011). Melatonin for the Control of Reproduction in Small Ruminants. Melatonin in the Promotion of Health, Taylor & Francis. [2nd ed.].","DOI":"10.1201\/b11101-26"},{"key":"ref_11","first-page":"331","article-title":"Physiology of Seasonal Breeding: A Review","volume":"7","author":"Vasantha","year":"2016","journal-title":"J. Vet. Sci. Technol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"155","DOI":"10.1016\/S0921-4488(03)00038-5","article-title":"Seasonality of reproduction in sheep","volume":"48","author":"Rosa","year":"2003","journal-title":"Small Rumin. Res."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"925","DOI":"10.1016\/j.theriogenology.2014.07.011","article-title":"Essential actions of melatonin in protecting the ovary from oxidative damage","volume":"82","author":"Cruz","year":"2014","journal-title":"Theriogenology"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"113620","DOI":"10.1016\/j.ygcen.2020.113620","article-title":"Central and peripheral actions of melatonin on reproduction in seasonal and continuous breeding mammals","volume":"300","author":"Reiter","year":"2021","journal-title":"Gen. Comp. Endocrinol."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Gonz\u00e1lez-Arto, M., Aguilar, D., Gaspar-Torrubia, E., Gallego, M., Carvajal-Serna, M., Herrera-Marcos, L.V., Serrano-Blesa, E., Hamilton, T.R.d.S., P\u00e9rez-P\u00e9, R., and Mui\u00f1o-Blanco, T. (2017). Melatonin MT1 and MT2 Receptors in the Ram Reproductive Tract. Int. J. Mol. Sci., 18.","DOI":"10.3390\/ijms18030662"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"563","DOI":"10.1071\/RD22194","article-title":"The melatonin system is expressed in the ovine uterus: Effect of the day of the oestrous cycle and undernutrition","volume":"35","author":"Sosa","year":"2023","journal-title":"Reprod. Fert. Dev."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"e240172","DOI":"10.1530\/REP-24-0172","article-title":"Exogenous melatonin ameliorates embryo\u2013maternal cross-talk in early pregnancy in sheep","volume":"168","author":"Viola","year":"2024","journal-title":"Reproduction"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"730","DOI":"10.5424\/sjar\/20110903-348-10","article-title":"Meta-analysis of the efficacy of melatonin implants for improving reproductive performance in sheep","volume":"9","author":"Palacin","year":"2011","journal-title":"Span. J. Agric. Res."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"16","DOI":"10.2298\/VETGL220308007K","article-title":"Various approaches to influence melatonin level in sheep reproduction","volume":"77","author":"Becskei","year":"2023","journal-title":"Vet. Glas."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"489","DOI":"10.1017\/S0003356100013064","article-title":"Effect of constant-release melatonin implants on the onset of oestrous activity and on reproductive performance in the ewe","volume":"52","author":"Durotoye","year":"1991","journal-title":"Anim. Sci."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"399","DOI":"10.1017\/S1751731107001383","article-title":"Effect of exogenous melatonin on the ovary, the embryo and the establishment of pregnancy in sheep","volume":"2","author":"Abecia","year":"2008","journal-title":"Animal"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"124","DOI":"10.1016\/j.anireprosci.2007.10.012","article-title":"Melatonin-improved reproductive performance in sheep bred out of season","volume":"109","author":"DeNicolo","year":"2008","journal-title":"Anim. Reprod. Sci."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Bouroutzika, E., Ciliberti, M.G., Caroprese, M., Theodosiadou, E., Papadopoulos, S., Makri, S., Skaperda, Z.-V., Kotsadam, G., Michailidis, M.-L., and Valiakos, G. (2021). Association of Melatonin Administration in Pregnant Ewes with Growth, Redox Status and Immunity of Their Offspring. Animals, 11.","DOI":"10.3390\/ani11113161"},{"key":"ref_24","first-page":"233","article-title":"Serum melatonin during human pregnancy","volume":"124","year":"1991","journal-title":"Acta Endocrinol."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Ejaz, H., Figaro, J.K., Woolner, A.M.F., Thottakam, B.M.V., and Galley, H.F. (2021). Maternal Serum Melatonin Increases During Pregnancy and Falls Immediately After Delivery Implicating the Placenta as a Major Source of Melatonin. Front. Endocrinol., 11.","DOI":"10.3389\/fendo.2020.623038"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1051\/rnd:19970111","article-title":"The characteristics of the melatonin secretory rhythm are not modified by the stage of pregnancy in ewes","volume":"37","author":"Zarazaga","year":"1997","journal-title":"Reprod. Nutr. Dev."},{"key":"ref_27","unstructured":"Bod\u00f3, I. (2001). The Tsigai or in Hungarian Berke Sheep. Living Heritage\u2014Old Historical Hungarian Livestock, Agroinform Kiad\u00f3. [1st ed.]."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Cunningham, K., Van Burgel, A., Kelman, K.R., Macleay, C.M., Paganoni, B.L., and Thompson, A.N. (2022). Interactions between Ewes and Rams during Mating Can Be Used to Predict Lambing Dates Accurately, but Not Sire. Animals, 12.","DOI":"10.3390\/ani12131707"},{"key":"ref_29","unstructured":"(2024, June 04). Pedigree Viewer. Version 6.5f. Available online: http:\/\/bkinghor@une.edu.au."},{"key":"ref_30","unstructured":"TIBCO Software Inc. (2025, April 02). Data Science Workbench. Statistica Version 14. Available online: http:\/\/tibco.com."},{"key":"ref_31","unstructured":"Szikszai, I. (2024). (Tsigai Seedstock Breeder, Csan\u00e1dpalota, Csongr\u00e1d-Csan\u00e1d County, Hungary), Personal communication."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2276","DOI":"10.1210\/endo-113-6-2276","article-title":"Pineal Melatonin Secretion Drives the Reproductive Response to Daylength in the Ewe","volume":"113","author":"Bittman","year":"1983","journal-title":"Endocrinology"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"908","DOI":"10.1080\/09291016.2013.781317","article-title":"Daily rhythm of blood melatonin concentrations in sheep of different ages","volume":"44","author":"Carcangiu","year":"2013","journal-title":"Biol. Rhythm Res."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"159","DOI":"10.1016\/0378-4320(93)90113-6","article-title":"Melatonin and seasonality in the sheep","volume":"33","author":"Williams","year":"1993","journal-title":"Anim. Reprod. Sci."},{"key":"ref_35","first-page":"E607","article-title":"The large variability in melatonin blood levels in ewes is under strong genetic influence","volume":"274","author":"Zarazaga","year":"1998","journal-title":"Am. J. Physiol."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"101","DOI":"10.1111\/j.1600-079X.2006.00333.x","article-title":"Annual pattern of plasma melatonin and progesterone concentrations in hair and wool ewe lambs kept under natural photoperiod at lower latitudes in the southern hemisphere","volume":"41","author":"Coelho","year":"2006","journal-title":"J. Pineal Res."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"482","DOI":"10.1210\/endo-98-2-482","article-title":"Radioimmunoassay of Serum Concentrations of Melatonin in Sheep Exposed to Different Lighting Regimens","volume":"98","author":"Rollag","year":"1976","journal-title":"Endocrinology"},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Harmat, L., Nagy, J., Somosk\u0151i, B., Alp\u00e1r, A., Fekete, S.G., and G\u00e1sp\u00e1rdy, A. (2024). Determination of Rhythmicity and Gestational Stage-Related Distribution of Blood Plasma Melatonin Concentrations in Donkey Mares. Vet. Sci., 11.","DOI":"10.20944\/preprints202406.0425.v1"},{"key":"ref_39","first-page":"3348","article-title":"The effects of leptin on plasma concentrations of prolactin, growth hormone, and melatonin vary depending on the stage of pregnancy in sheep","volume":"96","author":"Szczesna","year":"2018","journal-title":"J. Anim. Sci."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"465","DOI":"10.1113\/jphysiol.1991.sp018803","article-title":"Effects of different lighting regimes on daily hormonal and behavioral rhythms in the pregnant ewe and sheep fetus","volume":"442","author":"McMillen","year":"1991","journal-title":"J. Physiol."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"284","DOI":"10.1210\/endo-123-1-284","article-title":"Diurnal rhythms in plasma melatonin concentrations in the fetal sheep and pregnant ewe during late gestation","volume":"123","author":"Zemdegs","year":"1988","journal-title":"Endocrinology"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"2651","DOI":"10.3168\/jds.2021-20691","article-title":"Effect of circadian system disruption on the concentration and daily oscillations of cortisol, progesterone, melatonin, serotonin, growth hormone, and core body temperature in periparturient dairy cattle","volume":"105","author":"Hoang","year":"2022","journal-title":"J. Dairy Sci."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"559","DOI":"10.1016\/0022-4731(77)90262-X","article-title":"On the presence of melatonin in the pineal glands and plasma of foetal sheep","volume":"8","author":"Kennaway","year":"1977","journal-title":"J. Steroid Biochem."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1016\/j.anireprosci.2014.11.022","article-title":"Effect of melatonin or maternal nutrient restriction on vascularity and cell proliferation in the ovine placenta","volume":"153","author":"Eifert","year":"2015","journal-title":"Anim. Reprod. Sci."},{"key":"ref_45","doi-asserted-by":"crossref","unstructured":"McCarthy, R., Jungheim, E.S., Fay, J.C., Bates, K., Herzog, E.D., and England, S.K. (2019). Riding the Rhythm of Melatonin Through Pregnancy to Deliver on Time. Front. Endocrinol., 10.","DOI":"10.3389\/fendo.2019.00616"},{"key":"ref_46","unstructured":"Huchton, J.D. (1984). Melatonin Levels in Ewes and Lambs Under Suckled and Non-Suckled Regimens During the First Eight Weeks Postpartum. [Ph.D. Thesis, Texas A&M University]."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"2895","DOI":"10.1210\/en.2017-00254","article-title":"Deciphering the Function of the Blunt Circadian Rhythm of Melatonin in the Newborn Lamb: Impact on Adrenal and Heart","volume":"158","author":"Valenzuela","year":"2017","journal-title":"Endocrinology"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"97","DOI":"10.1677\/joe.0.1250097","article-title":"Emergence of the diurnal rhythm in plasma melatonin concentrations in newborn lambs delivered to intact or pinealectomized ewes","volume":"125","author":"Nowak","year":"1990","journal-title":"J. Endocrinol."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"362","DOI":"10.1016\/j.physbeh.2018.06.001","article-title":"Circadian rhythms of melatonin and behaviour in juvenile sheep in field conditions: Effects of photoperiod, environment and weaning","volume":"194","author":"Wyse","year":"2018","journal-title":"Physiol. Behav."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"301","DOI":"10.1677\/joe.0.0790301","article-title":"The importance of prolactin for lactation in the ewe","volume":"79","author":"Hooley","year":"1978","journal-title":"J. Endocrinol."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"182","DOI":"10.1016\/j.smallrumres.2012.10.006","article-title":"Short-day and melatonin effects on milking parameters, prolactin profiles and growth-hormone secretion in lactating sheep","volume":"109","author":"Molik","year":"2013","journal-title":"Small Rumin. Res."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"83","DOI":"10.1677\/JOE-07-0640","article-title":"Identification of salsolinol in the mediobasal hypothalamus of lactating ewes and its relation to suckling-induced prolactin and GH release","volume":"198","author":"Misztal","year":"2008","journal-title":"J. Endocrinol."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"207","DOI":"10.1893\/0005-3155-85.4.207","article-title":"Circadian rhythms of ewes suckling singletons versus twins during the second week of lactation","volume":"85","author":"Schmitt","year":"2014","journal-title":"Bios"},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"1426","DOI":"10.1016\/j.psyneuen.2012.12.011","article-title":"Rapid effects of melatonin on hormonal and behavioral stressful responses in ewes","volume":"38","author":"Guesdon","year":"2013","journal-title":"Psychoneuroendocrinology"},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1210\/endo.130.1.1309321","article-title":"Suckling is a persistent stimulus to the adrenocortical system of the rat","volume":"130","author":"Walker","year":"1992","journal-title":"Endocrinology"},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"bnaa002","DOI":"10.1210\/endrev\/bnaa002","article-title":"Dynamics of ACTH and Cortisol Secretion and Implications for Disease","volume":"41","author":"Lightman","year":"2020","journal-title":"Endocr. Rev."},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"E6466","DOI":"10.1073\/pnas.1703779114","article-title":"Dynamic responses of the adrenal steroidogenic regulatory network","volume":"114","author":"Spiga","year":"2017","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"1","DOI":"10.5187\/jast.2024.e105","article-title":"Melatonin effects on animal behavior: Circadian rhythm, stress response, and modulation of behavioral patterns","volume":"67","author":"Song","year":"2025","journal-title":"J. Anim. Sci. Technol."},{"key":"ref_59","first-page":"587","article-title":"Chronic melatonin treatment and the hypothalamo-pituitary-adrenal axis in the rat: Attenuation of the secretory response to stress and effects on hypothalamic neuropeptide content and release","volume":"89","author":"Konakchieva","year":"1997","journal-title":"Biol. Cell"},{"key":"ref_60","first-page":"77","article-title":"Melatonin, circadian dysregulation, and sleep in mental disorders","volume":"15","author":"Trakht","year":"2008","journal-title":"Prim. Psychiatry"},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"592","DOI":"10.1111\/cen.13548","article-title":"Pulsatility of glucocorticoid hormones in pregnancy: Changes with gestation and obesity","volume":"88","author":"Stirrat","year":"2018","journal-title":"Clin. Endocrinol."},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"e13012","DOI":"10.1111\/jne.13012","article-title":"Visualising oxytocin neurone activity in vivo: The key to unlocking central regulation of parturition and lactation","volume":"33","author":"Perkinson","year":"2021","journal-title":"J. Neuroendocrinol."},{"key":"ref_63","doi-asserted-by":"crossref","unstructured":"Bienboire-Frosini, C., Marcet-Rius, M., Orihuela, A., Dom\u00ednguez-Oliva, A., Mora-Medina, P., Olmos-Hern\u00e1ndez, A., Casas-Alvarado, A., and Mota-Rojas, D. (2023). Mother\u2013young bonding: Neurobiological aspects and maternal biochemical signaling in altricial domesticated mammals. Animals, 13.","DOI":"10.3390\/ani13030532"},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"361","DOI":"10.1016\/0031-9384(85)90309-9","article-title":"The Importance of olfactory bulb noradrenalin for maternal recognition in sheep","volume":"35","author":"Pissonnier","year":"1985","journal-title":"Physiol. Behav."},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"167","DOI":"10.1002\/dev.10130","article-title":"Maternal experience influences the establishment of visual\/auditory, but not olfactory recognition of the newborn lamb by ewes at parturition","volume":"43","author":"Keller","year":"2003","journal-title":"Dev. Psychobiol."},{"key":"ref_66","first-page":"2211","article-title":"PHYSIOLOGY AND ENDOCRINOLOGY SYMPOSIUM: Alterations in uteroplacental hemodynamics during melatonin supplementation in sheep and cattle","volume":"95","author":"Lemley","year":"2017","journal-title":"J. Anim. Sci."},{"key":"ref_67","doi-asserted-by":"crossref","first-page":"4017","DOI":"10.1113\/jphysiol.2008.154351","article-title":"Evidence of a role for melatonin in fetal sheep physiology: Direct actions of melatonin on fetal cerebral artery, brown adipose tissue and adrenal gland","volume":"586","author":"Valenzuela","year":"2008","journal-title":"J. Physiol."},{"key":"ref_68","doi-asserted-by":"crossref","unstructured":"Be\u00f1aldo, F.A., Llanos, A.J., Araya-Quijada, C., Rojas, A., Gonzalez-Candia, A., Herrera, E.A., Ebensperger, G., Cabello, G., Valenzuela, G.J., and Ser\u00f3n-Ferr\u00e9, M. (2019). Effects of Melatonin on the Defense to Acute Hypoxia in Newborn Lambs. Front. Endocrinol., 10.","DOI":"10.3389\/fendo.2019.00433"}],"container-title":["Veterinary Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2306-7381\/12\/4\/336\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T17:10:47Z","timestamp":1760029847000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2306-7381\/12\/4\/336"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,4,5]]},"references-count":68,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2025,4]]}},"alternative-id":["vetsci12040336"],"URL":"https:\/\/doi.org\/10.3390\/vetsci12040336","relation":{},"ISSN":["2306-7381"],"issn-type":[{"value":"2306-7381","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,4,5]]}}}