{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T12:11:31Z","timestamp":1789992691532,"version":"4.0.1"},"reference-count":43,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2026,9,20]],"date-time":"2026-09-20T00:00:00Z","timestamp":1789862400000},"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>Limited information is available regarding the role of melatonin in regulating seasonal reproductive activity and oxidative stress in sheep under subtropical climatic conditions. Therefore, the present study evaluated the effect of melatonin administration on reproductive performance, hormonal profile, and antioxidant status in ewes during breeding and non-breeding seasons. A total of 48 clinically healthy multiparous ewes (2\u20135 years old) were equally divided into breeding and non-breeding season groups (n = 24 each). During each season, animals were allocated into four treatment groups: Group I (control; corn oil @ 1 mL\/animal, s\/c, n = 6), Group II (melatonin @ 10 mg\/animal, s\/c, n = 6), Group III (melatonin @ 20 mg\/animal, s\/c, n = 6), and Group IV (melatonin @ 40 mg\/animal, s\/c, n = 6). Melatonin administration significantly improved estrus response and conception rate during both seasons. During the breeding season, estrus response was observed in 33.33%, 100%, 100%, and 66.67% of animals in Groups I, II, III, and IV, respectively, whereas during the non-breeding season, estrus response was 0%, 83.33%, 100%, and 33.33%, respectively. Similarly, conception rates during the breeding season were 50%, 100%, 100%, and 66.67%, respectively, while corresponding values during the non-breeding season were 0%, 80%, 100%, and 50%. Serum estrogen concentration increased significantly (p &lt; 0.05) in Groups II and III, particularly on day 7 during the breeding season and on day 14 during the non-breeding season. Progesterone concentration increased significantly (p &lt; 0.05) on day 30 following 10 and 20 mg melatonin treatment during both seasons. Antioxidant enzyme activities, including glutathione peroxidase, superoxide dismutase, and catalase, were significantly enhanced following melatonin treatment. In conclusion, subcutaneous administration of melatonin improved reproductive performance, hormonal profile, and antioxidant status in sheep under subtropical conditions, with 20 mg melatonin\/animal producing the most favorable responses, particularly during the non-breeding season.<\/jats:p>","DOI":"10.3390\/ani16182954","type":"journal-article","created":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T11:05:53Z","timestamp":1789988753000},"page":"2954","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Effect of Melatonin Supplementation on Reproductive Performance, Hormonal Profile and Antioxidant Status in Sheep Under Subtropical Conditions"],"prefix":"10.3390","volume":"16","author":[{"given":"Chandan","family":"Singh","sequence":"first","affiliation":[{"name":"Department of Veterinary Gynaecology and Obstetrics, College of Veterinary Science and Animal Husbandry, Rewa 486001, Madhya Pradesh, India"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"methodology","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"}]},{"given":"J. S.","family":"Rajoriya","sequence":"additional","affiliation":[{"name":"Department of Veterinary Gynaecology and Obstetrics, College of Veterinary Science and Animal Husbandry, Rewa 486001, Madhya Pradesh, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9092-9048","authenticated-orcid":false,"given":"A. K.","family":"Singh","sequence":"additional","affiliation":[{"name":"Department of Veterinary Physiology and Biochemistry, College of Veterinary Science and Animal Husbandry, Rewa 486001, Madhya Pradesh, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"B. K.","family":"Ojha","sequence":"additional","affiliation":[{"name":"Department of Veterinary Gynaecology and Obstetrics, College of Veterinary Science and Animal Husbandry, Rewa 486001, Madhya Pradesh, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Deepak","family":"Ningwal","sequence":"additional","affiliation":[{"name":"Department of Veterinary Gynaecology and Obstetrics, College of Veterinary Science and Animal Husbandry, Rewa 486001, Madhya Pradesh, India"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"resources","vocabulary":"credit"}]},{"given":"Madhuri","family":"Dhurvey","sequence":"additional","affiliation":[{"name":"Department of Veterinary Gynaecology and Obstetrics, College of Veterinary Science and Animal Husbandry, Rewa 486001, Madhya Pradesh, India"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"investigation","vocabulary":"credit"}]},{"given":"Atul Kumar","family":"Verma","sequence":"additional","affiliation":[{"name":"Department of Veterinary Gynaecology and Obstetrics, College of Veterinary and Animal Science, Sardar Vallabhbhai Patel University of Agriculture & Technology, Modipuram, Meerut 250110, Uttar Pradesh, India"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-original-draft","vocabulary":"credit"}]},{"given":"S. S.","family":"Tomar","sequence":"additional","affiliation":[{"name":"Department of Animal Genetics and Breeding, Nanaji Deshmukh Veterinary Science University, Jabalpur 482004, Madhya Pradesh, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Amit Kumar","family":"Jha","sequence":"additional","affiliation":[{"name":"Department of Animal Genetics and Breeding, College of Veterinary Science and Animal Husbandry, Rewa 486001, Madhya Pradesh, India"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"formal-analysis","vocabulary":"credit"}]},{"given":"S. S.","family":"Peepar","sequence":"additional","affiliation":[{"name":"ICAR-Indian Veterinary Research Institute, Bareilly 243122, Uttar Pradesh, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mahak","family":"Singh","sequence":"additional","affiliation":[{"name":"Animal Reproduction Laboratory, ICAR-Nagaland Centre, Medziphema 797106, Nagaland, India"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5464-1151","authenticated-orcid":false,"given":"Megha","family":"Pande","sequence":"additional","affiliation":[{"name":"Animal Physiology and Biochemistry Division, ICAR-Central Sheep and Wool Research Institute, Avikanagar 304501, Rajasthan, India"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7783-3559","authenticated-orcid":false,"given":"Rohit","family":"Gupta","sequence":"additional","affiliation":[{"name":"ICAR-Central Institute for Research on Buffalo, Sub Campus, Nabha 147201, Patiala, India"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"data-curation","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,20]]},"reference":[{"key":"ref_1","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_2","first-page":"48","article-title":"Evaluation of the efficiency of estrus synchronization protocols combined with natural service and ultrasonography on ewe reproductive performance during non-breeding season","volume":"25","author":"Kumar","year":"2024","journal-title":"Iran. J. Vet. Res."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"2136","DOI":"10.1016\/j.theriogenology.2004.08.015","article-title":"Ovarian follicular development and oocyte quality in anestrous ewes treated with melatonin, a controlled internal drug release (CIDR) device and follicle stimulating hormone","volume":"63","author":"Luther","year":"2005","journal-title":"Theriogenology"},{"key":"ref_4","first-page":"111","article-title":"The effect of melatonin implants on breeding activity and litter size in commercial sheep flocks in the UK","volume":"50","author":"Haresign","year":"1990","journal-title":"Anim. Prod."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"165","DOI":"10.1016\/S0378-4320(02)00117-3","article-title":"The effect of melatonin implants on the response to the male effect and on the subsequent cyclicity of Rasa Aragonesa ewes implanted in April","volume":"72","author":"Zuniga","year":"2002","journal-title":"Anim. Reprod. Sci."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"431","DOI":"10.1016\/S0361-9230(97)00223-2","article-title":"Control of the circannual rhythm of reproduction by melatonin in the ewe","volume":"44","author":"Malpaux","year":"1997","journal-title":"Brain Res. Bull."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"356","DOI":"10.1016\/j.theriogenology.2005.05.038","article-title":"The effect of melatonin implants during the seasonal anestrus on embryo production after superovulation in aged high-prolificacy Rasa Aragonesa ewes","volume":"65","author":"Forcada","year":"2006","journal-title":"Theriogenology"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"10","DOI":"10.1016\/j.smallrumres.2005.12.018","article-title":"The effect of melatonin on the reproductive performance of three sheep breeds in Spain","volume":"69","author":"Abecia","year":"2007","journal-title":"Small Rumin. Res."},{"key":"ref_9","unstructured":"Olcese, J. (2000). Melatonin modulation of prolactin and gonadotrophin secretion: Systems ancient and modern. Melatonin After Four Decades\u2014An Assessment of Its Potential, Kluwer Academic Publishers."},{"key":"ref_10","first-page":"57","article-title":"Melatonin: A potent, endogenous hydroxyl radical scavenger","volume":"1","author":"Tan","year":"2000","journal-title":"Endocr. J."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"253","DOI":"10.1111\/jpi.12360","article-title":"Melatonin as an antioxidant: Under promises but over delivers","volume":"61","author":"Reiter","year":"2016","journal-title":"J. Pineal Res."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1186\/1757-2215-5-5","article-title":"The role of melatonin as an antioxidant in the follicle","volume":"5","author":"Tamura","year":"2012","journal-title":"J. Ovarian Res."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"173","DOI":"10.1016\/j.anireprosci.2012.01.011","article-title":"Hormonal control of reproduction in small ruminants","volume":"130","author":"Abecia","year":"2012","journal-title":"Anim. Reprod. Sci."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Duan, Z., Liu, M., Li, J., Liu, K., Qi, Q., Yu, Z., Samoo, H.A., Wang, C., and Hou, J. (2025). Melatonin implantation improves the reproductive performance of estrus-synchronized ewes during seasonal anestrus and enhances the antioxidant and steroidogenic capacities of granulosa and luteal cells. Antioxidants, 14.","DOI":"10.3390\/antiox14070895"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"e6750","DOI":"10.7717\/peerj.6750","article-title":"Melatonin improves the efficiency of super-ovulation and timed artificial insemination in sheep","volume":"7","author":"Song","year":"2019","journal-title":"PeerJ"},{"key":"ref_16","first-page":"184","article-title":"Micro titer plate assay for superoxide dismutase using MTT reduction by superoxide","volume":"35","author":"Madesh","year":"1998","journal-title":"Indian J. Biochem. Biophys."},{"key":"ref_17","first-page":"16","article-title":"A method of determining catalase activity","volume":"1","author":"Korolyuk","year":"1988","journal-title":"Lab. Delo"},{"key":"ref_18","unstructured":"Gonz\u00e1lez-Bulnes, A., Menchaca, A., Martin, G.B., and Mart\u00ednez-Ros, P. (2020). Seventy years of progestagen treatments for management of sheep reproduction: Looking to the future. Animals, 10."},{"key":"ref_19","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_20","doi-asserted-by":"crossref","first-page":"67","DOI":"10.1016\/j.theriogenology.2019.12.006","article-title":"Melatonin improves development, mitochondrial function and promotes the meiotic resumption of sheep oocytes from in vitro grown secondary follicles","volume":"144","author":"Barros","year":"2020","journal-title":"Theriogenology"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"e70061","DOI":"10.1111\/rda.70061","article-title":"Melatonin improves the development ability of sheep embryos by reducing ROS during IVEP","volume":"60","author":"Zhang","year":"2025","journal-title":"Reprod. Domest. Anim."},{"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","first-page":"170","DOI":"10.1016\/j.smallrumres.2019.03.019","article-title":"Alleviation of reproductive seasonality in Barki ewes using CIDR-eCG with or without melatonin","volume":"174","author":"Ramadan","year":"2019","journal-title":"Small Rumin. Res."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"246","DOI":"10.1007\/s11259-026-11188-2","article-title":"Effect of estrus synchronization\/induction in OuledDjellal ewes using combinations of melatonin, GnRH, and prostaglandin F2\u03b1 on fertility parameters","volume":"50","author":"Mehallaine","year":"2026","journal-title":"Vet. Res. Commun."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"223","DOI":"10.1016\/j.jare.2024.04.025","article-title":"Exploring melatonin\u2019s multifaceted role in female reproductive health: From follicular development to lactation and its therapeutic potential in obstetric syndromes","volume":"70","author":"Li","year":"2025","journal-title":"J. Adv. Res."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1341","DOI":"10.1038\/s12276-020-00491-w","article-title":"Melatonin stimulates aromatase expression and estradiol production in human granulosa-lutein cells: Relevance for high serum estradiol levels in patients with ovarian hyperstimulation syndrome","volume":"52","author":"Cheng","year":"2020","journal-title":"Exp. Mol. Med."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"108534","DOI":"10.1016\/j.reprotox.2024.108534","article-title":"Melatonin-mediated actions and circadian functions that improve implantation, fetal health and pregnancy outcome","volume":"124","author":"Reiter","year":"2024","journal-title":"Reprod. Toxicol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"e250084","DOI":"10.1530\/RAF-25-0084","article-title":"Melatonin mitigates autophagy: Unlocking conditional resilience in sheep trophoblast cells exposed to a hypoxic environment","volume":"6","author":"Viola","year":"2025","journal-title":"Reprod. Fertil."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"333","DOI":"10.1016\/j.tox.2006.09.018","article-title":"Melatonin has dose-dependent effects on folliculogenesis, oocyte maturation capacity and steroidogenesis","volume":"228","author":"Adriaens","year":"2006","journal-title":"Toxicology"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1058","DOI":"10.1016\/j.theriogenology.2014.01.032","article-title":"Dose-dependent effect of melatonin on postwarming development of vitrified ovine embryos","volume":"81","author":"Succu","year":"2014","journal-title":"Theriogenology"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"e12514","DOI":"10.1111\/jpi.12514","article-title":"Melatonin and its metabolites vs oxidative stress: From individual actions to collective protection","volume":"65","author":"Galano","year":"2018","journal-title":"J. Pineal Res."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"122693","DOI":"10.1016\/j.lfs.2024.122693","article-title":"Melatonin regulates the antioxidant capacity of sheep granulosa cells through a novel uORF-Nrf2aa mediated Nrf2\/KEAP1 pathway","volume":"349","author":"Ma","year":"2024","journal-title":"Life Sci."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Ko\u0142odziejska, R., Wo\u017aniak, A., Bilski, R., Weso\u0142owski, R., Kupczyk, D., Porzych, M., Wr\u00f3blewska, W., and Pawluk, H. (2025). Melatonin-A powerful antioxidant in neurodegenerative diseases. Antioxidants, 14.","DOI":"10.3390\/antiox14070819"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Gharanjik, S., Ebrahimi, A., Somee, L.R., Chaghakaboodi, Z., and Alipour, H. (2025). Systemic role of melatonin in enhancing temperature stress tolerance in fenugreek: Coordination of antioxidant defense, hormonal regulation, energy status, sulfur metabolism, and diosgenin pathway genes. BMC Plant Biol., 25.","DOI":"10.1186\/s12870-025-07224-z"},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Mehaisen, G.M.K., Saeed, A.M., Gad, A., Abass, A.O., Arafa, M., and El-Sayed, A. (2015). Antioxidant capacity of melatonin on preimplantation development of fresh and vitrified rabbit embryos: Morphological and molecular aspects. PLoS ONE, 10.","DOI":"10.1371\/journal.pone.0139814"},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Bouroutzika, E., Kouretas, D., Papadopoulos, S., Veskoukis, A.S., Theodosiadou, E., Makri, S., Paliouras, C., Michailidis, M.L., Caroprese, M., and Valasi, I. (2020). Effects of melatonin administration to pregnant ewes under heat-stress conditions, in redox status and reproductive outcome. Antioxidants, 9.","DOI":"10.3390\/antiox9030266"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"139","DOI":"10.1016\/j.jneuroim.2005.05.002","article-title":"Anti-inflammatory actions of melatonin and its metabolites, N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK) and N1-acetyl-5-methoxykynuramine (AMK), in macrophages","volume":"165","author":"Mayo","year":"2005","journal-title":"J. Neuroimmunol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"e12703","DOI":"10.1111\/jpi.12703","article-title":"The melatonin metabolite N1-acetyl-5-methoxykynuramine facilitates long-term object memory in young and aging mice","volume":"70","author":"Iwashita","year":"2021","journal-title":"J. Pineal Res."},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Zhou, L.T., Gokyer, D., Madkins, K., Beestrum, M., Horton, D.E., Duncan, F.E., and Babayev, E. (2024). The effects of heat stress on the ovary, follicles and oocytes: A systematic review. bioRxiv.","DOI":"10.1101\/2024.12.04.626831"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"26","DOI":"10.1186\/s40104-020-00537-z","article-title":"Review of the impact of heat stress on reproductive performance of sheep","volume":"12","author":"Kind","year":"2021","journal-title":"J. Anim. Sci. Biotechnol."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"17163","DOI":"10.1038\/s41598-025-01173-1","article-title":"Heat stress affects the functionality of the ovine cumulus-oocyte complex and subsequent in vitro embryo production","volume":"15","author":"Maside","year":"2025","journal-title":"Sci. Rep."},{"key":"ref_42","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_43","doi-asserted-by":"crossref","unstructured":"Ji, P., Liu, Y., Yan, L., Jia, Y., Zhao, M., Lv, D., Yao, Y., Ma, W., Yin, D., and Liu, F. (2023). Melatonin improves the vitrification of sheep morulae by modulating transcriptome. Front. Vet. Sci., 10.","DOI":"10.3389\/fvets.2023.1212047"}],"container-title":["Animals"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-2615\/16\/18\/2954\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T11:34:31Z","timestamp":1789990471000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-2615\/16\/18\/2954"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,20]]},"references-count":43,"journal-issue":{"issue":"18","published-online":{"date-parts":[[2026,9]]}},"alternative-id":["ani16182954"],"URL":"https:\/\/doi.org\/10.3390\/ani16182954","relation":{},"ISSN":["2076-2615"],"issn-type":[{"value":"2076-2615","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,20]]}}}