Animal Reproduction (AR)
Animal Reproduction (AR)

Systematic review of hormonal strategies to improve fertility in rams

Estela Garza-Brenner; Fernando Sánchez-Dávila; Keyla Mauleón-Tolentino; Cecilia Carmela Zapata-Campos; Carlos Luna-Palomera; Javier Hernandez-Melendez; Marisol Gonzalez-Delgado; José Fernando Vázquez-Armijo

Downloads: 1
Views: 132


Reviewing the current state of knowledge on reproductive performance and productive traits in rams has many advantages. First, the compilation of this information will serve as a literature resource for scientists conducting research around the world and will contribute to the understanding of the data collected and interpreted by researchers on the different hormonal strategies used to improve reproductive performance in rams. Second, it will allow scientists to identify current knowledge gaps and set future research priorities in ram reproduction. Rams play an important role in the global flock economy, but their reproductive analysis has been limited in the use of hormonal technologies to increase the productivity of sheep flocks. In this review, we cite the most important works on six hormones that, in one way or another, modify the hypothalamus-pituitary-gonadal axis, at different doses, in and out of the reproductive season, breeds, application methods, among other factors. The overall aim is to increase the reproductive efficiency of rams in different scenarios and, in some cases, of other species due to the lack of limited information on rams.


rams, kisspeptin, eCG, PGF2α, GnRH


Abbas M, Khan MIUR, Hameed N, Rehman A, Mohsin I, Bilal M, Shahzad M. Melatonin along with eCG improves fresh semen quality and plasma concentrations of melatonin and testosterone during non-breeding season in Beetal bucks. Small Rumin Res. 2021;205:106569.

Abdel-Ghani MA, Mahmoud GB. Effect of kisspeptin injection on reproductive performance of Ossimi rams in subtropics. Small Rumin Res. 2019;179:43-7.

Abd-Elhafeez HH, Hassan AHS, Hussein MT. Melatonin administration provokes the activity of dendritic reticular cells in the seminal vesicle of Soay ram during the non-breeding season. Sci Rep. 2021;11(1):872. PMid:33441634.

Abecia JA, Araya J, Chemineau P, Palacios C, Keller M, Delgadillo JA. Photoperiod-melatonin-induced, sexually-activated rams increase pregnancy rate and number of lambs per ewe in a ram effect. Large Anim Rev. 2018;24:31-5.

Abecia JA, Mura MC, Carvajal-Serna M, Pulinas L, Macías A, Casao A, Pérez-Pe R, Carcangiu V. Polymorphisms of the Melatonin Receptor 1A (MTNR1A) gene influence the age at first mating in autumn-born ram-lambs and sexual activity of adult rams in spring. Theriogenology. 2020;157:42-7. PMid:32799126.

Abou-Khalil NS, Mahmoud GB. Reproductive, antioxidant and metabolic responses of Ossimi rams to kisspeptin. Theriogenology. 2020;142:414-20. PMid:31711707.

Abril-Sánchez S, Freitas-de-Melo A, Giriboni J, Santiago-Moreno J, Ungerfeld R. Sperm collection by electroejaculation in small ruminants: A review on welfare problems and alternative techniques. Anim Reprod Sci. 2019;205:1-9. PMid:30962039.

Adams TE. Using gonadotropin-releasing hormone (GnRH) and GnRH analogs to modulate testis function and enhance the productivity of domestic animals. Anim Reprod Sci. 2005;88(1-2):127-39. PMid:15970407.

Aguirre V, Orihuela A, Vazquez R. Seasonal variations in sexual behavior, testosterone, testicular size and semen characteristics, as affected by social dominance, of tropical hair rams (Ovis aries). Anim Sci J. 2007;78(4):417-23.

Aguirre-Zapata C, Perez-Cervera Y, Salinas-Marìn R. El ácido siálico, coraza de los seres vivos. Ciencia UANL. 2023;26(119):28-35.

Aibazov M, Trukhachev V, Selionova M, Malorodov V. Seasonal changes in testis size, testosterone levels and sperm production quality in meat rams. Reprod Domest Anim. 2022;57(10):1125-35. PMid:35701877.

Akar M, Çevik M, Kocaman A. Effects of melatonin administration on testicular volume, testicular hemodynamics, semen parameters, and antioxidant status during the non-breeding season in bafra rams. Social Sci Res Network. 2023;1-10.

Aké-Villanueva JR, Aké-López JR, Magaña-Monforte JG, Segura-Correa JC. Reproductive behavior in hair sheep rams under tropical conditions. Trop Anim Health Prod. 2019;51(6):1627-35. PMid:30806954.

Al-Ameri MH, Anwer T, Eldin TAA. The effect of hormonal treatment with kisspeptin, GnRH and hCG on semen characteristics in buck Cyprus goats during non-breeding season as compared with breeding season. Al-Anbar J Vet Sci. 2019;12(1):74-88.

Almeida OFX, Lincoln GA. Reproductive photorefractoriness in rams and accompanying changes in the patterns of melatonin and prolactin secretion. Biol Reprod. 1984;30(1):143-58. PMid:6696961.

Amodei R, Jonker SS, Whitler W, Estill CT, Roselli CE. The GnRH antagonist degarelix suppresses gonadotropin secretion and pituitary sensitivity in midgestation sheep fetuses. Endocrinology. 2022;163(2):bqab262.

Anjum S, Anuradha A, Krishna A. A possible direct action of oxytocin on spermatogenesis and steroidogenesis in pre‐pubertal mouse. Andrologia. 2018;50(4):e12958. PMid:29363158.

Argiolas A, Melis MR. The role of oxytocin and the paraventricular nucleus in the sexual behaviour of male mammals. Physiol Behav. 2004;83(2):309-17. PMid:15488547.

Arroyo J, Sánchez-Hernández NJ, Ávila-Serrano NY, Camacho-Escobar MA, Rodríguez-De-La-Torre MM. Reproductive seasonality in creole hair sheep in the tropic. Trop Anim Health Prod. 2016;48(1):219-22. PMid:26477030.

Asadi N, Bahmani M, Kheradmand A, Rafieian-Kopaei M. The impact of oxidative stress on testicular function and the role of antioxidants in improving it: a review. J Clin Diagn Res. 2017;11(5):IE01-05. PMid:28658802.

Assad NI, Pandey AK, Sharma LM. Oxytocin, functions, uses and abuses: a brief review. Theriogenology Insight-an Internat. J Reprod All Anim. 2016;6(1):1-17.

Assani BVM, Ayssiwede SB, Kinnou MS. Evaluation of the effects of melatonin implants on testicular and spermatic parameters of rams raised in station in the niayes zone in senegal. Anim Vet Sci. 2023;11(3):55-63.

Assinder SJ, Carey M, Parkinson T, Nicholson HD. Oxytocin and vasopressin expression in the ovine testis and epididymis: changes with the onset of spermatogenesis. Biol Reprod. 2000;63(2):448-56. PMid:10906049.

Avdi M, Banos G, Stefos K, Chemineau P. Seasonal variation in testicular volume and sexual behavior of Chios and Serres rams. Theriogenology. 2004;62(1-2):275-82. PMid:15159120.

Bahadi MA, Al-Badwi MA, Samara EM, Abdoun KA, Alhidary IA, Al-Haidary AA. Group-training of rams at puberty for artificial vagina-mediated semen collection and its influence on semen quality and sexual behavior. Anim Reprod. 2023;20(1):e20220051. PMid:37101423.

Beltramo M, Decourt C. Towards New Strategies to Manage Livestock Reproduction Using Kisspeptin Analogs. Theriogenology. 2018;112:2-10. PMid:28916209.

Beracochea F, Manes J, Viera MN, Santiago-Moreno J, Ungerfeld R. administration of equine chorionic gonadotrophin (ecg) to rams to improve the reproductive performance during the non-breeding season. Livest Sci. 2020;240:104125.

Beracochea F, Viera MN, Acevedo L, Santiago-Moreno J, Ungerfeld R. Equine Chorionic Gonadotropin (eCG) Improves bucks’ semen quality during the non breeding season. Reprod Domest Anim. 2018;53(5):1096-102. PMid:29885006.

Berndtson WE, Igboeli G. Spermatogenesis, sperm output and seminal quality of Holstein bulls electroejaculated after administration of oxytocin. J Reprod Fertil. 1988;82(2):467-75. PMid:3361481.

Bó GA, Menchaca A. Prohibition of hormones in animal reproduction: what to expect and what to do? Anim Reprod. 2023;20(2):e20230067. PMid:37720723.

Borg KE, Esbenshade KL, Johnson BH, Lunstra DD, Ford JJ. Effects of sexual experience, season, and mating stimuli on endocrine concentrations in the adult ram. Horm Behav. 1992;26(1):87-109. PMid:1563732.

Bozkurt T, Turk G, Gur S. Effects of exogenous oxytocin on serologic and seminal steroids and semen characteristics in rams. Turk J Vet Anim Sci. 2007;31(5):303-9.

Bronson FH. Climate change and seasonal reproduction in mammals. Philos Trans R Soc Lond B Biol Sci. 2009;364(1534):3331-40. PMid:19833645.

Calderón-Leyva G, Meza-Herrera CA, Rodriguez-Martinez R, Angel-García O, Rivas-Muñoz R, Delgado-Bermejo JV, Véliz-Deras FG. Effect of glutamate and/or testosterone administration on appetitive and consummatory sexual behaviors in pubertal rams and their influence on the reproductive performance of nulliparous anovulatory ewes. J Vet Behav. 2019;30:96-102.

Capitan SS, Antiporda GS, Momongan VG. Reaction Time, semen output and semen quality of buffalo bulls aster pre-collection injection of prostaglandin F2 Alpha (PGF2 Alpha). Asian-Australas J Anim Sci. 1990;3(4):343-6.

Cárdenas‐Gallegos MA, Aké‐López JR, Centurión‐Castro F, Magaña‐Monforte JG. The breed and season effects on scrotal circumference and semen characteristics of hair sheep rams under tropical conditions. Reprod Domest Anim. 2012;47(6):e92-4. PMid:22372836.

Cardona Tobar KM, López Álvarez DC, Álvarez Franco LÁ. Estudios de asociación genómica en ovinos de América Latina. Revisión. Rev Mex Cienc Pecu. 2020;11(3):859-83.

Cardoso FM, Queiroz GF. Duration of the cycle of the seminiferous epithelium and daily sperm production of brazilian hairy rams. Anim Reprod Sci. 1988;17(1-2):77-84.

Casao A, Cebrián I, Asumpção ME, Pérez-Pé R, Abecia JA, Forcada F, Cebrián-Pérez JA, Muiño-Blanco TO. Seasonal variations of melatonin in ram seminal plasma are correlated to those of testosterone and antioxidant enzymes. Reprod Biol Endocrinol. 2010a;8(1):59. PMid:20540737.

Casao A, Mendoza N, Pérez‐Pé R, Grasa P, Abecia JA, Forcada F, Muino‐Blanco T. Melatonin prevents capacitation and apoptotic‐like changes of ram spermatozoa and increases fertility rate. J Pineal Res. 2010b;48(1):39-46. PMid:19919602.

Çiğdem ÇS, Tekin K, ÇIL B, Akcay E. The effects of oxytocin and PGF2α injections on semen quality and libido in buck. Kafkas Univ Vet Fak Derg. 2019;25(5):645-50.

Clemente N, Orihuela A, Flores-Pérez I, Aguirre V, Ortiz A, Solano J, Valencia J. Reproductive activity of Suffolk ewes in seasonal anestrus after being exposed to Saint Croix or Suffolk rams. J Appl Anim Res. 2012;40(3):203-7.

Courot M, Ortavant R. Endocrine control of spermatogenesis in the ram. J Reprod Fertil Suppl. 1981;30:47-60. PMid:6820054.

Cruz-Espinoza F, Gallegos-Sánchez J, Mendieta-Galán TA, Márquez-Hernández CI, Salazar-Ortiz J. Reproductive management of the ram (Ovis orientalis aries). Agro Product. 2021;5(V):1-8.

Da EB, Faten G, Shaker MH. The effect of oxytocin, prostaglandin F2α or GnRH injection on fresh and frozen-thawed semen characteristics of rams. Assiut Vet Med J. 2013;59:214-29.

Daham AF. Effect of PGF2α injection on semen characters of local bucks. Al-Qadisiyah J Vet Med Sci. 2012;11(3):1.

Dalmazzo A, Losano JD, Angrimani DS, Pereira IV, Goissis MD, Francischini MC, Nichi M. Immunolocalisation and expression of oxytocin receptors and sex hormone-binding globulin in the testis and epididymis of dogs: correlation with sperm function. Reprod Fertil Dev. 2019;31(9):1434-43. PMid:31046900.

Daniel JA, Foradori CD, Whitlock BK, Sartin JL. Reproduction and beyond, Kisspeptin in Ruminants. J Anim Sci Biotechnol. 2015;6(1):23. PMid:26110054.

De Rensis F, López-Gatius F. Use of equine chorionic gonadotropin to control reproduction of the dairy cow: a review. Reprod Domest Anim. 2014;49(2):177-82. PMid:24456154.

Ebling FJ, Lincoln GA, Wollnik F, Anderson N. Effects of constant darkness and constant light on circadian organization and reproductive responses in the ram. J Biol Rhythms. 1988;3(4):365-84. PMid:2979646.

Echeverría J. Endocrinología reproductiva: prostaglandina F2a en vacas. Revisión bibliográfica. REDVET Rev Electrón Vet. 2006;7:1-12.

El-Shalofy AS, Hedia MG. Effects of buserelin administration on testicular blood flow and plasma concentrations of testosterone and estradiol-17β in rams. Domest Anim Endocrinol. 2021a;77:106646. PMid:34175682.

El‐Shalofy AS, Hedia MG. Exogenous oxytocin administration improves the testicular blood flow in rams. Andrologia. 2021b;53(10):e14193. PMid:34309888.

El-Sherry TM, Abdel‐Ghani MA, Mahmoud GB, Ezzat AA. Kisspeptin injection improved the semen characteristics and sperm rheotaxis in ossimi ram. Reprod Domest Anim. 2020;55(2):240-7. PMid:31880370.

Espírito Santo CG, Balaro MFA, Santos JDR, Correia LFL, de Souza CV, Taira AR, Tilbrook A. Semen quality, testosterone values, and testicular and accessory gland parameters in rams receiving sustained stimulation with low doses of buserelin. Anim Prod Sci. 2022;62(2):152-62.

Estienne MJ, Harper AF, Knight JW, Barb CR, Rampacek GB. Sexual behavior after treatment with prostaglandin-F2α in boars with suppressed concentrations of gonadal steroids. Appl Anim Behav Sci. 2004;89(1-2):53-7.

Estienne MJ. A Review of the effects of prostaglandins on sexual behavior in boars. Appl Anim Behav Sci. 2014;154:1-7.

Ezzat AA, Saito H, Sawada T, Yaegashi T, Goto Y, Nakajima Y, Jin J, Yamashita TK, Sawai Hashizume T. The role of sexual steroid hormones in the direct stimulation by Kisspeptin-10 of the secretion of luteinizing hormone, follicle-stimulating hormone and prolactin from bovine anterior pituitary cells. Anim Reprod Sci. 2010;121(3-4):267-72. PMid:20594780.

FAO. [homepage on the Internet]. Datos sobre alimentación y agricultura; Roma: FAOSTAT; 2023 [cited 2023 Jan 16]. Available from:

Fierro S, Gil J, Viñoles C, Olivera-Muzante J. The use of prostaglandins in controlling estrous cycle of the ewe: a review. Theriogenology. 2013;79(3):399-408. PMid:23219520.

Fitzgerald JA, Stellflug JN. Effects of melatonin on seasonal changes in reproduction of rams. J Anim Sci. 1991;69(1):264-75. PMid:2005022.

Fjellström D, Kihlstrom JE, Melin P. The effect of synthetic Oxytocin upon seminal characteristics and sexual behaviour in male rabbits. J Reprod Fertil. 1968;17(1):207-9. PMid:5697442.

Foster DL, Jackson LM, Padmanabhan V. Programming of GnRH feedback controls timing puberty and adult reproductive activity. Mol Cell Endocrinol. 2006;254-255:109-19. PMid:16723182.

Frungieri MB, Gonzalez-Calvar SI, Matzkin ME, Mayerhofer A, Calandra RS. Sources and functions of prostaglandins in the testis: evidence for their relevance in male (in) fertility. Anim Reprod. 2018;4(3):63-9.

Gimeno-Martos S, Casao A, Yeste M, Cebrián-Pérez JA, Muiño-Blanco T, Pérez-Pé R. Melatonin reduces CAMP-Stimulated capacitation of ram spermatozoa. Reprod Fertil Dev. 2019;31(2):420-31. PMid:30209004.

Giriboni J, Gökdal Ö, Eren V, Yaralı E, Santiago-Moreno J, Ungerfeld R. Daily administration of a gnrh analogue enhances sperm quality in bucks during the non-breeding season. Anim Reprod Sci. 2019;200:43-50. PMid:30473147.

Godfrey RW, Collins JR, Gray ML. Evaluation of sexual behavior of hair sheep rams in a tropical environment. J Anim Sci. 1998;76(3):714-7. PMid:9535328.

González-Arto M, Aguilar D, Gaspar-Torrubia E, Gallego M, Carvajal-Serna M, Herrera-Marcos L, Serrano-Blesa E, Hamilton T, Pérez-Pé R, Muiño-Blanco T, Cebrián-Pérez J, Casao A. Melatonin MT1 and MT2 receptors in the ram reproductive tract. Int J Mol Sci. 2017;18(3):662. PMid:28335493.

Gonzalez-Arto M, Hamilton TRS, Gallego M, Gaspar-Torrubia E, Aguilar D, Serrano-Blesa E, Abecia JA, Pérez-Pé R, Muiño-Blanco T, Cebrián-Pérez JA, Casao A. Evidence of melatonin synthesis in the ram reproductive tract. Andrology. 2016;4(1):163-71. PMid:26742835.

Grösch S, Niederberger E, Geisslinger G. Investigational drugs targeting the prostaglandin e2 signaling pathway for the treatment of inflammatory pain. Expert Opin Investig Drugs. 2017;26(1):51-61. PMid:27841017.

Guerrero JM, Carrillo-Vico A, Lardone PJ. La melatonina. Inv Cien. 2007;373:30-8.

Gündoğan M, Baki D, Yeni D. Reproductive seasonality in sheep. Acta Agric Scand A Anim Sci. 2003;53(4):175-9.

Hanif M, Williams HL. The effects of melatonin and light treatment on the reproductive performance of yearling Suffolk rams. Br Vet J. 1991;147(1):49-56. PMid:2018917.

Harman H, Serpek B. The effect of zinc supplementation on plasma melatonin and kisspeptin levels in rams. Livest Stud. 2022;62(1):31-6.

Harris G, Nicholson H. Characterisation of the biological effects of neurohypophysial peptides on seminiferous tubules. J Endocrinol. 1998;156(1):35-42. PMid:9496231.

Hashem NM, El-Hawy AS, El-Bassiony MF, El-Hamid ISA, Gonzalez-Bulnes A, Martinez-Ros P. Use of GnRH-encapsulated chitosan nanoparticles as an alternative to eCG for Induction of estrus and ovulation during non-breeding season in sheep. Biology (Basel). 2023;12(3):351. PMid:36979043.

Hashem NM, Gonzalez-Bulnes A. Nanotechnology and Reproductive management of farm animals: challenges and advances. Animals (Basel). 2021;11(7):1932. PMid:34209536.

Hawken PAR, Martin GB. Sociosexual stimuli and gonadotropin-releasing hormone/luteinizing hormone secretion in sheep and goats. Domest Anim Endocrinol. 2012;43(2):85-94. PMid:22533940.

Hedia MG, El-Belely MS, Ismail ST, El-Maaty AMA. Seasonal changes in testicular ultrasonogram pixel-intensity and their association with semen characteristics in rams. Asian Pac J Reprod. 2020;9(1):49-54.

Hedia MG, El-Shalofy AS. Oxytocin improves testicular blood flow without enhancing the steroidogenic activity in Baladi goats. Asian Pac J Reprod. 2022;11(5):223.

Hitesh HS, Kansal G. Application of GnRH modulators in controlling reproductive cycle in farm animals: a review. Pharm J. 2022;7:4288-301.

Ibrahim MA. Influence of Oxytocin and Prostaglandin on semen characteristics and process of ejaculation in buffalo bulls. Acta Vet Hung. 1988;36(1-2):3-10. PMid:3202047.

Inaba T, Nakayama Y, Tani H, Tamada H, Kawate N, Sawada T. Oxytocin gene expression and action in goat testis. Theriogenology. 1999;52(3):425-34. PMid:10734377.

Jiang DL, Xu YL, Pan JQ, Fan D, Shen X, Li WY, Ou-Yang HJ, Xu DN, Tian YB, Huang YM. Effects of melatonin on testicular function in adult male mice under different photoperiods. Anim Reprod. 2022;19(3):e20220038. PMid:36189166.

Jung Y, Yoon M. Oxytocin receptor expression in stallion testes and epididymides. Domest Anim Endocrinol. 2021;74:106562. PMid:33038836.

Kawakami E, Masaoka Y, Hirano T, Hori T, Tsutsui T. Changes in plasma testosterone levels and semen quality after 3 injections of a GnRH analogue in 3 dogs with spermatogenic dysfunction. J Vet Med Sci. 2005;67(12):1249-52. PMid:16397384.

Kleemann DO, Kelly JM, Arney LJ, Len J, Tilbrook AJ, Walker SK. Sexual behaviour, semen quality and fertility of young Border Leicester rams administered melatonin during spring. Anim Reprod Sci. 2021;231:106804. PMid:34271495.

Kleemann DO, Kelly JM, Arney LJ, Tilbrook AJ, Walker SK. Melatonin dose: testicular and testosterone response in Border Leicester rams during spring. Livest Sci. 2022;260:104928.

Knickerbocker JJ, Sawyer HR, Amann RP, Tekpetey FR, Niswender GD. Evidence for the presence of oxytocin in the ovine epididymis. Biol Reprod. 1988;39(2):391-7. PMid:3179387.

Kokolis N, Theodosiadou E, Tsantarliotou M, Rekkas C, Goulas P, Smokovitis A. The effect of melatonin implants on blood testosterone and acrosin activity in spermatozoa of the ram. Andrologia. 2000;32(2):107-14. PMid:10755193.

Kumar T, Kumar P, Saini N, Bhalothia SK, Prakash C, Mahla AS, Kumar A. Shielding effect of melatonin improves seminal quality and oxidative stress indices during chilled storage of ram semen. Trop Anim Health Prod. 2022;54(3):197. PMid:35662381.

Leyva-Corona JC, Angulo-Valenzuela NI, Laborin-Escalante BM, Gastelum-Delgado MA, Silva-Ávila NJ, Luna-Nevárez P, Aragón-López CE, Sánchez-Castro MA, Morales-Pablos MI. Reproductive performance of hair ewes and rams implanted with Melatonin previous to the anestrus season in Northwest Mexico. Trop Anim Health Prod. 2023;55(3):174. PMid: 37099050.

Li C, Zhou X. Melatonin and male reproduction. Clin Chim Acta. 2015;446:175-80. PMid:25916694.

Lincoln GA, Almeida OF, Arendt J. Role of melatonin and circadian rhythms in seasonal reproduction in rams. J Reprod Fertil Suppl. 1981;30:23-31. PMid:6962843.

Lincoln GA, Maeda KI. Reproductive effects of placing micro-implants of melatonin in the mediobasal hypothalamus and preoptic area in rams. J Endocrinol. 1992;132(2):201-15. PMid:1541920.

Luna-Palomera C, Macías-Cruz U, Sánchez-Dávila F, Peralta-Torres JA, Ojeda-Robertos NF. Características seminales y niveles de testosterona en carneros pelibuey tratados con oxitocina exógena. Arch Zootec. 2021;70(271):312-7.

Luna-Palomera C, Macías-Cruz U, Sánchez-Dávila F. Superovulatory response and embryo quality in Katahdin ewes treated with FSH or FSH plus eCG during non-breeding season. Trop Anim Health Prod. 2019;51(5):1283-8. PMid:30652251.

Ma J, Yang H, Liu L, Wan Y, Wang F. Melatonin alleviated oxidative stress induced by energy restriction on sheep leydig cells through Sirt1/Sod2 Pathway. Theriogenology. 2021;173:83-92. PMid:34352672.

Macías-Cruz U, Álvarez-Valenzuela FD, Correa-Calderón A, Molina-Ramírez L, González-Reyna A, Soto-Navarro S, Avendaño-Reyes L. Pelibuey ewe productivity and subsequent pre-weaning lamb performance using hair-sheep breeds under a confinement system. J Appl Anim Res. 2009;36(2):255-60.

Macías-Cruz U, Correa-Calderón A, Mellado M, Meza-Herrera CA, Aréchiga CF, Avendaño-Reyes L. Thermoregulatory response to outdoor heat stress of hair sheep females at different physiological state. Int J Biometeorol. 2018a;62(12):2151-60. PMid:30244321.

Macías-Cruz U, Gastélum MA, Avendaño-Reyes L, Correa-Calderón A, Mellado M, Chay-Canul A, Arechiga CF. Variaciones en las respuestas termorreguladoras de ovejas de pelo durante los meses de verano en un clima desértico. Rev Mex Cienc Pecu. 2018b;9(4):739-53.

Macías-Cruz U, Gastélum MA, Avendaño-Reyes L, Correa-Calderón A, Mellado M, Chay-Canul A, Arechiga CF. Variations in the thermoregulatory responses of hair ewes during the summer months in a desert climate. Rev Mex Cienc Pecu. 2018c;9:738-53.

Mamontova TV, Selionova MI, Aibazov AM. Sexual activity and sperm production of charolais and Ile-De-France rams in different seasons of the year. Sh Biol. 2021;56(4):4.

Maatoq ZQ, Fahid TA, Abd Al Bari A. Evaluation the sperms of bucks by Sperm Quality Analyzer after injection by Prostaglandin F2α. Bas J Vet Res. 2015;14(2):199-206.

Masoumi R, Towhidi A, Javaremi AN, Nabizadeh H, Zhandi M. Influence of PGF_ {2\alpha} on semen quality and libido in Holstein bulls. Turk J Vet Anim Sci. 2011;35(1):1-6.

Matsuoka T, Imai H, Asakuma S, Kohno H, Fukui Y. Changes of fructose concentrations in seminal plasma and glucose and testosterone concentrations in blood plasma in rams over the course of a year. J Reprod Dev. 2006;52(6):805-10. PMid:16988491.

Meccariello R, Fasano S, Pierantoni R. Kisspeptins, new local modulators of male reproduction: a comparative overview. Gen Comp Endocrinol. 2020;299:113618. PMid:32950583.

Medrano A, Contreras CFBS, Herrera FMS, Alcantar-Rodriguez AMS. Melatonin as an Antioxidant Preserving Sperm from Domestic Animals. Asian Pac J Reprod. 2017;6(6):241.

Min KS, Hiyama T, Seong HH, Hattori N, Tanaka S, Shiota K. Biological activities of tethered equine chorionic gonadotropin (eCG) and its deglycosylated mutants. J Reprod Dev. 2004;50(3):297-304. PMid:15226594.

Moenter SM, Evans NP. Gonadotropin‐releasing hormone (GnRH) measurements in pituitary portal blood: a history. J Neuroendocrinol. 2022;34(5):e13065. PMid:34918405.

Moradi M, Karimi I, Ahmadi S, Mohammed LJ. The necessity of antioxidant inclusion in caprine and ovine semen extenders: A systematic review complemented with computational insight. Reprod Domest Anim. 2020;55(9):1027-43. PMid:32597508.

Moraes JC, Mattevi MS, Ferreira JM. Chromosome studies in Brazilian rams. Vet Rec. 1980;107(21):489-90. PMid:7445349.

Moreira F, Hammon D. Lutalyse and cloprostenol: clearing up misconceptions. Pfizer Animal Health Technical Bulletin. 2012;(1):1-12.

Moura Fernandes DA, de Souza CV, Alvarez Balaro MF, Rodrigues Santos JD, Barbosa dos Santos VM, Campos Pereira da Costa MM, da Silva Carvalho AB, Rios Rodrigues AL, Ungerfeld R, Brandão FZ. Response of rams to electroejaculation following the administration of oxytocin and cloprostenol with or without GnRH. Theriogenology. 2021;173:32-6. PMid:34265698.

Murphy BD. Equine chorionic gonadotropin: an enigmatic but essential tool. Anim Reprod. 2018;9:223-30.

Narenji Sani R, Ghazvinian K, Shabani G, Ghae Mashk Gharavi J. Effects of oxytocin on semen quality of Zel Rams in nonbreeding season. J Vet Lab Res. 2014;6(2):111-6.

Nicholson HD, Parkinson TJ, Lapwood KR. Effects of Oxytocin and vasopressin on sperm transport from the cauda epididymis in sheep. J Reprod Fertil. 1999;117(2):299-305. PMid:10690197.

Nozdrachev AD, Kovalenko RI, Chernysheva MP, Semenova EP. The Effect of the intraventricular administration of oxytocin on the functional activity of the epiphysis, adrenals and gonads and on the behavior of rats. Fiziol Zh Im I M Sechenova. 1994;80(2):88-97. PMid:7522792.

Ofosu J, Qazi IH, Fang Y, Zhou G. Use of melatonin in sperm cryopreservation of farm animals: a brief review. Anim Reprod Sci. 2021;233:106850. PMid:34537566.

Olfati A, Moghaddam GH, Daghigh KH, Karami-Shabankareh H. Effects of prostaglandin F2α treatment on semen characteristics of crossbred rams in the non-breeding season. J Cell Anim Biol. 2013;7: 16-20.

Orihuela Trujillo A. La conducta sexual del carnero: revisión. Rev Mex Cienc Pecu. 2012;5(1):49-89.

Palacín I, Abecia JA, Forcada F, Casao A, Cebrián JÁ, Muiño T, Pontes JM. Effects of exogenous melatonin treatment on out-of-season ram fertility. Ital J Anim Sci. 2008;7(2):199-206.

Palmer CW, Amundson SD, Brito LFC, Waldner CL, Barth AD. Use of oxytocin and cloprostenol to facilitate semen collection by electroejaculation or transrectal massage in bulls. Anim Reprod Sci. 2004;80(3-4):213-23.

Pérez RV, Macías-Cruz U, Reyes LA, Correa-Calderón A, Rivera ALL. Impacto del estrés por calor en la producción de ovinos de pelo. Revisión. Rev Mex Cienc Pecu. 2020;11(1):205-22.

Perkins A, Fitzgerald JA. The behavioral component of the ram effect: the influence of ram sexual behavior on the induction of estrus in anovulatory ewes. J Anim Sci. 1994;72(1):51-5. PMid:8138503.

Perkins A, Roselli CE. The ram as a model for behavioral neuroendocrinology. Horm Behav. 2007;52(1):70-7. PMid:17482616.

Pool KR, Rickard JP, De Graaf SP. Exogenous melatonin advances the ram breeding season and increases testicular function. Sci Rep. 2020a;10(1):1-11. PMid:32546776.

Pool KR, Rickard JP, Tumeth E, de Graaf SP. Treatment of rams with melatonin implants in the non-breeding season improves post-thaw sperm progressive motility and DNA integrity. Anim Reprod Sci. 2020b;221:106579. PMid:32919308.

Pool KR, Rickard JP, De Graaf SP. Melatonin improves the motility and DNA integrity of frozen-thawed ram spermatozoa likely via suppression of mitochondrial superoxide production. Domest Anim Endocrinol. 2021;74:106516. PMid:32712540.

Prestel L, Joerling J, Failing K, Wagner H, Wehrend A. Suppression of reproductive function in juvenile rams by a slow-release gonadotropin-releasing hormone implant. Open Vet J. 2022;12(2):171-81. PMid:35603069.

Pretorius PS. Mating behaviour of rams. J S Afr Vet Assoc. 1972;43(2):155-61. PMid:4616083.

Price EO. Male sexual behavior. Vet Clin North Am Food Anim Pract. 1987;3(2):405-22. PMid:3304584.

Quintero LAZ, Rojero RDM, Lazo CC, Gutiérrez IR, Méndez JV. Efecto de los implantes subcutáneos de melatonina y la suplementación alimentaria, sobre la inducción de la actividad ovárica en ovejas Pelibuey durante la época de anestro. Vet Mex. 2001;32:237-47.

Ramaswamy S, Weinbauer GF. Endocrine control of spermatogenesis: role of FSH and LH/ testosterone. Spermatogenesis. 2014;4(2):e996025.

Ramírez AA, Villalvazo VM, Arredondo ES, Ramirez HA, Magaña H. D-Cloprostenol enhances estrus synchronization in tropical hair sheep. Trop Anim Health Prod. 2018;50(5):991-6. PMid:29429114.

Reiter RJ, Paredes SD, Manchester LC, Tan DX. Reducing oxidative/nitrosative stress: a newly-discovered genre for melatonin. Crit Rev Biochem Mol Biol. 2009;44(4):175-200. PMid:19635037.

Reiter RJ, Tan DX, Manchester LC, Tamura H. Melatonin defeats neurally-derived free radicals and reduces the associated neuromorphological and neurobehavioral damage. J Physiol Pharmacol. 2007;6(suppl 6):5-22. PMid:18212398.

Rekik M, Taboubi R, Ben Salem I, Fehri Y, Sakly C, Lassoued N, Hilali ME. Melatonin administration enhances the reproductive capacity of young rams under a southern Mediterranean environment. Anim Sci J. 2015;86(7):666-72. PMid:25689168.

Rietema SE, Hawken PAR, Scott CJ, Lehman MN, Martin GB, Smith JT. Arcuate nucleus kisspeptin response to increased nutrition in rams. Reprod Fertil Dev. 2019;31(11):1682-91. PMid:31511141.

Rizkallah N, Chambers CG, de Graaf SP, Rickard JP. Factors affecting the survival of ram spermatozoa during liquid storage and options for improvement. Animals (Basel). 2022;12(3):244. PMid:35158568.

Romanello N, Botta D, Giro A, Moura ABB, Pantoja MHA, Barreto AN, Garcia AR. Effect of GnRH on scrotal surface temperature, testicular volume and sperm parameters of bulls with poor semen quality. Anim Reprod. 2018;15(3):459.

Rosa HJ, Juniper DT, Bryant MJ. Effects of recent sexual experience and melatonin treatment of rams on plasma testosterone concentration, sexual behaviour and ability to induce ovulation in seasonally anoestrous ewes. J Reprod Fertil. 2000;120(1):169-76. PMid:11006159.

Rosa HJD, Bryant MJ. Seasonality of reproduction in sheep. Small Rumin Res. 2003;48(3):155-71.

Rosa HJD, Bryant MJ. The ‘ram effect’as a way of modifying the reproductive activity in the ewe. Small Rumin Res. 2002;45(1):1-16.

Roselli CE. Programmed for preference: the biology of same-sex attraction in rams. Neurosci Biobehav Rev. 2020;114:12-5. PMid:32311371.

Ruan YC, Shum W, Gruber CW, Stadler B, Whittaker MR, Exintaris B, Middendorff R. Oxytocin in the male reproductive tract; the therapeutic potential of oxytocin-agonists and-antagonists. Front Endocrinol (Lausanne). 2020;11:565731. PMid:33193084.

Sá Geraldo A, Pinto PHN, da Silva Carvalho AB, da Costa MMCP, Santos JDR, Taira AR, Brandão FZ. Reproductive seasonality of hair rams under tropical conditions: an alternative for non-seasonal lamb production?. Trop Anim Health Prod. 2024;56:4.

Sakamoto K, Kamimura M, Kurozumi S, Ito S. Prostaglandin F2 alpha receptor. J Lipid Mediat Cell Signal. 1995;12(2-3):405-11. PMid:8777582.

Sánchez-Davila F, Bernal H, Colín J, Olivares E, del Bosque AS, Ledezma R, Ungerfeld R. Environmental factors and interval from the introduction of rams to estrus in postpartum saint croix sheep. Trop Anim Health Prod. 2011;43(4):887-91. PMid:21225458.

Sánchez-Davila F, Bernal-Barragan H, Vazquez-Armijo JF, López-Villalobos N, Ledezma-Torres RA, Grizelj J, Garza-Brenner E, Arce-Vasquez N, Palomera CL, Luna C. Annual Variation in Reproductive Parameters and Sexual Behaviour of Saint Croix Rams in a Semi-Desert Region in Mexico. J Appl Anim Res. 2020;48(1):499-506.

Sánchez‐Davila F, Hernández‐Melo VA, Ledezma‐Torres RA, Bernal‐Barragán H, Luna‐Palomera C, Ungerfeld R. Cloprostenol enhances sexual behaviour and semen quality in growing lambs more effectively than dinoprost. Reprod Domest Anim. 2022;57(6):611-5. PMid:35188980.

Santos SI, Sánchez-Dávila F, Vázquez-Armijo JF, Ledezma-Torres RA, del Bosque-González SA, Luna Palomera C, Bernal-Barragán H. Changes in sexual behaviour and semen quality associated with age and type of enclosure of saint croix rams in different seasons of the year. Ital J Anim Sci. 2015;14(4):678-83.

Schanbacher BD, Lunstra DD. Acute and chronic effects of gonadotropin releasing hormone on reproductive characteristics of rams during the nonbreeding season. J Anim Sci. 1977;44(4):650-5. PMid:323207.

Scott CJ, Rose JL, Gunn AJ, McGrath BM. Kisspeptin and the regulation of the reproductive axis in domestic animals. J Endocrinol. 2019;240(1):1-16. PMid:30400056.

Seminara SB. Mechanisms of Disease: The First Kiss—a Crucial Role for Kisspeptin-1 and Its Receptor, G-Protein-Coupled Receptor 54, in Puberty and Reproduction. Nat Clin Pract Endocrinol Metab. 2006;2(6):328-34. PMid:16932310.

Shahat AM, Thundathil JC, Kastelic JP. Melatonin improves testicular hemodynamics and sperm quality in rams subjected to mild testicular heat stress. Theriogenology. 2022a;188:163-9. PMid:35691188.

Shahat AM, Thundathil JC, Kastelic JP. Melatonin or L-Arginine in semen extender mitigate reductions in quality of frozen-thawed sperm from heat-stressed rams. Anim Reprod Sci. 2022b;238:106934. PMid:35123317.

Shayestehyekta M, Mohammadi T, Soltani L, PooyanMehr M. Effect of different concentrations of melatonin on ram epididymal spermatozoa recovered post-mortem under oxidative stress conditions and storage at 4° C. Reprod Domest Anim. 2022;57(12):1520-8. PMid:35980596.

Stadler B, Whittaker MR, Exintaris B, Middendorff R. Oxytocin in the male reproductive tract; the therapeutic potential of oxytocin-agonists and-antagonists. Front Endocrinol (Lausanne). 2020;11:565731. PMid:33193084.

Stewart WC, Scasta JD, Taylor JB, Murphy TW, Julian AAM. Invited Review: mineral nutrition considerations for extensive sheep production systems. Appl Anim Sci. 2021;37(3):256-72.

Tilbrook AJ, Cameron AWN. The contribution of the sexual behaviour of rams to successful mating of ewes under field conditions. In: author. Reproductive physiology of merino sheep - concepts and consequences. Nedlands: The University of Western Australia; 1990. p. 143-60.

Tiptanavattana N, Pakdeesanaeha T, Thongsima T, Techarungchaikul S, Tharasanit T. Expression of oxytocin receptors and oxytocin assisted electroejaculation in the domestic cat (Felis catus). Reprod Domest Anim. 2022;57(5):489-97. PMid:35044000.

Titiroongruang J, Tummaruk P. Effects of Prostaglandin F2α on serum testosterone and sperm output in holstein friesian bulls in tropical climates. Thai J Vet Med Suppl. 2011;41:159-60.

Tölü C, Yazgan N, Akbağ HI, Yurtman İY, Savaş T. Effects of melatonin implants on reproductive performance of dairy sheep and dairy goats. Reprod Domest Anim. 2022;57(6):665-72. PMid:35247006.

Traas AM, Root Kustritz MV. Effect of administrating oxytocin or prostaglandin F2 α on characteristics of the canine ejaculate. Clin Trials. 2004;45(12):999-1002. PMid:15646846.

Tsantarliotou MP, Kokolis NA, Smokovitis A. Melatonin administration increased plasminogen activator activity in ram spermatozoa. Theriogenology. 2008;69(4):458-65. PMid:18045674.

Ungerfeld R, Bielli A. No change detected in body weight, scrotal circumference, semen characteristics and sexual behaviour during the development of prepubertal milchschaf lambs after weekly administration of ECG. Reprod Domest Anim. 2008;43(4):400-2. PMid:18226016.

Ungerfeld R, Casuriaga D, Giriboni J, Freitas-de-melo A, Silveira P, Zandonadi F. Administration of cloprostenol and oxytocin before electroejaculation in goat bucks reduces the needed amount of electrical stimulation without affecting seminal quality. Theriogenology. 2018;107:1-5. PMid:29120706.

Ungerfeld R, Clemente N, Bonjour L, Orihuela A. Equine chorionic gonadotrophin administration to rams improves their effectiveness to stimulate anoestrous ewes (the “ram effect”). Anim Reprod Sci. 2014;149(3-4):194-8. PMid:25059200.

Ungerfeld R, Clemente N, Orihuela A. Treatments with eCG and courtship behaviour in rams during the breeding and the non-breeding seasons. Anim Prod Sci. 2019;59(5):865.

Ungerfeld R, Díaz-Muñiz AF, Bernal-Barragán H, Sánchez-Dávila F. Administration of a single dose of a PGF2α analogue (dinoprost) before sexual tests did not improve ram’s sexual behaviour. Trop Anim Health Prod. 2020;52(6):3417-23. PMid:32935323.

Ungerfeld R, Forsberg M, Rubianes E. Overview of the response of anoestrous ewes to the ram effect. Reprod Fertil Dev. 2004;16(4):479-90. PMid:15315747.

Ungerfeld R, Giriboni J, Toledano‐Díaz A, Guerrero M, Santiago‐Moreno J. Administration of carbetocin—a long‐acting oxytocin analogue—before sperm collection by transrectal ultrasound‐guided massage of the accessory sex glands in bucks (Capra hircus) and ibexes (Capra pyrenaica). Reprod Domest Anim. 2023;58(1):20-6. PMid:36066997.

Ungerfeld R. Comportamiento sexual del carnero. In Anais da Reuniao Anual da VABRAA; 2021; Campo Grande. Campo Grande: Editora UFMS; 2021a. p. 40-46.

Ungerfeld R. Dominance, hierarchy, and reproduction in rams and goat bucks. Rev Bras Reprod Anim. 2021b;45(4):168-72.

Ungerfeld R. Manejo de la estacionalidad reproductiva en pequeños rumiantes. Arch Latinoam Prod Anim. 2016;24(2):111-6.

Ungerfeld R. Seasonal reproductive patterns and effectiveness as teasers (ram effect) of Corriedale and Milchschaf rams. Anim Prod Sci. 2012;52(11):1036-41.

Wang JM, Li ZF, Yang WX. What does androgen receptor signaling pathway in sertoli cells during normal spermatogenesis tell us? Front Endocrinol (Lausanne). 2022;13:838858. PMid:35282467.

Webster JR, Suttie JM, Veenvliet BA, Manley TR, Littlejohn RP. Effect of melatonin implants on secretion of luteinizing hormone in intact and castrated rams. J Reprod Fertil. 1991;92(1):21-31. PMid:2056492.

Whittington K, Assinder SJ, Parkinson T, Lapwood KR, Nicholson HD. Function and localization of oxytocin receptors in the reproductive tissue of rams. Reproduction. 2001;122(2):317-25. PMid:11467983.

Wilson PR, Lapwood KR. Studies of reproductive development in Romney rams: II. LH and testosterone secretion following single or repeated doses of gonadotropin-releasing hormone (GnRH). Biol Reprod. 1979;20(4):971-5. PMid:378280.

Witt-Enderby PA, Bennett J, Jarzynka MJ, Firestine S, Melan MA. Melatonin receptors and their regulation: biochemical and structural mechanisms. Life Sci. 2003;72(20):2183-98. PMid:12628439.

Wurtman RJ. Melatonin as a hormone in humans: a history. Yale J Biol Med. 1985;58(6):547-52. PMid:3914144.

Yousef MS, Megahed GA, Abozed GF, Hayder M, Abd-Elhafeez HH, Rawy MS. Exogenous gonadotropin-releasing hormone counteracts the adverse effect of scrotal insulation on testicular functions in bucks. Sci Rep. 2022;12(1):7869. PMid:35551262.

Yu HD, Reiter RJ. Melatonin: biosynthesis, physiological effects, and clinical applications. In: Melatonin and reproduction in sheep and goats. Boca Raton: CRC Press; 1993. Chap. 10, p. 253-88.

Yu K, Deng SL, Sun TC, Li YY, Liu YX. Melatonin regulates the synthesis of steroid hormones on male reproduction: a review. Molecules. 2018;23(2):447. PMid:29462985.

Zaher HA, Alawaash SA, Swelum AA. Effects of season and breed on the reproductive performance of sheep. Journal of Animal Reproduction and Biotechnology. 2020;35(2):149-54.

Zhao W, Adjei M, Zhang Z, Yuan Z, Cisang Z, Song T. The role of GnRH in Tibetan male sheep and goat reproduction. Reprod Domest Anim. 2023;58(9):1179-87. PMid:37492901.

Submitted date:

Accepted date:

6661ec51a9539532423fa275 animreprod Articles
Links & Downloads

Anim Reprod

Share this page
Page Sections