Administration of equine chorionic gonadotropin (eCG) increases testosterone production and sperm concentration in rams during the non-breeding (sexual rest) season

Neftali Clemente Ovando, Virginio Aguirre Flores, Reyes Vázquez Rosales, Fernando Iván Flores Pérez

Abstract


Background: Hormonal treatments are applied to rams to increase their reproductive parameters and characteristics during the sexual rest season. A hormonal alternative is the use of equine chorionic gonadotropin (eCG), however, it has been evaluated for short periods in rams. Objective: To evaluate the long-term effect (63 days) of eCG administration on testosterone levels, sexual behavior, and sperm activity of rams during the sexual rest season. Methodology: 20 rams were randomly assigned to one of two groups, the treated group: GeCG, n=10; they were administered intramuscularly two doses of 1000 IU of eCG on days 0 and 4 of the experiment and testosterone levels, their service capacity, testicular and sperm characteristics were evaluated on days -14, -7, -1, 7, 14, 28 and 63. The group control: GCON, n=10; no hormones were administered, and they were evaluated in the same manner as the GeCG. Results: Testosterone levels and sperm numbers increased more in GeCG than in GCON, P = 0.0006 and P = 0.03, respectively. The reaction time to the first ejaculation decreased (P < 0.05) in the GeCG from 526.6 ± 101.6 to 199.8 ± 113.0 seconds. The number of ejaculations during the serviceability test in the GeCG increased twofold (P < 0.01). In the GCON, there were no statistical changes in any of the previous variables. Implications: The application of eCG in rams stimulates testosterone levels and increases sperm concentration and sexual performance during the sexual rest season, which could improve the productive rates of a herd. However, factors to consider include dose, frequency of administration, breed, and season of the year. Conclusion: The application of two doses of 1000 IU of equine chorionic gonadotropin at an interval of four days in rams during the sexual rest season (63 days) increases blood testosterone levels, sperm concentration, and the number of ejaculations, in addition to reducing reaction time.  

Keywords


PMSG; reproductive seasonality; serving capacity tests; ram; semen.

Full Text:

PDF

References


Abecia, J.A., Chemineau, P. and Delgadillo, J.A., 2024. Advances in photoperiodic and bio-stimulations of seasonal reproduction in small ruminants. Small Ruminant Research, 235, 107286. https://doi.org/10.1016/j.smallrumres.2024.107286

Abecia, J.A., Chemineau, P., Gómez, A., Keller, M., Forcada, F. and Delgadillo, J.A., 2016. Presence of photoperiod-melatonin-induced, sexually-activated rams in spring advances puberty in autumn-born ewe lambs. Animal Reproduction Science, 170, pp. 114-120. https://doi.org/10.1016/j.anireprosci.2016.04.011

Aguirre, V., Orihuela, A. and Vázquez, R., 2007. Effect of semen collection frequency on seasonal variation in sexual behaviour, testosterone, testicular size and semen characteristics of tropical hair rams (Ovis aries). Tropical Animal Health and Production, 39, pp. 271–277. https://doi.org/10.1007/s11250-007-9010-8

Arroyo, L.J., Gallegos-Sánchez, J., Villa-Godoy, A., Berruecos, J.M., Perera, G. and Valencia, J., 2007. Reproductive activity of Pelibuey and Suffolk ewes at 19° north latitude. Animal Reproduction Science, 102, pp. 24–30. https://doi.org/10.1016/j.anireprosci.2006.09.025

Ávalos-Rodríguez, A., González-Santos, J.A., Vargas-Ibarra, A.K. and Herrera-Barragán, J.A., 2018. Evaluación seminal: concentración espermática. In: Recolección y manipulación seminal in vitro. Universidad Autónoma Metropolitana, pp. 24-26. epub 978-607-28-1300-7

Avdi, M., Banos, G., Stefos, K. and Chemineau, P., 2004. Seasonal variation in testicular volume and sexual behavior of Chios and Serres rams. Theriogenology, 62, pp. 275–282. https://doi.org/10.1016/j.theriogenology.2003.10.004

Beracochea, F., Manes, J., Viera, M.N., Santiago-Moreno, J. and Ungerfeld, R., 2020. Administration of equine Chorionic Gonadotrophin (eCG) to rams to improve the reproductive performance during the non-breeding season. Livestock Science, 240, 04125. https://doi.org/10.1016/j.livsci.2020.104125

Beracochea, F., Viera, M.N., Acevedo, L., Santiago-Moreno, J. and Ungerfeld, R., 2018. Equine Chorionic Gonadotropin (eCG) improves bucks' semen quality during the nonbreeding season. Reproduction in Domestic Animals, 53, pp. 1096–1102. https://doi.org/10.1111/rda.13209

Calderón-Leyva, G., Meza-Herrera, C.A., Rodriguez-Martinez, R., Angel-García, O., Rivas-Muñoz, R., Delgado-Bermejo, J.V. and Véliz-Deras, F.G., 2019. 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. Journal of Veterinary Behavior, 30 pp. 96–102. https://doi.org/10.1016/j.jveb.2018.12.008

Cárdenas-Gallegos, M.A., Aké-López, J.R., Centurión-Castro, F. and Magaña-Monforte, J.G., 2012. The breed and season effects on scrotal circumference and semen characteristics of hair sheep rams under tropical conditions. Reproduction in Domestic Animals, 47, pp. 92–94. https://doi.org/10.1111/j.1439-0531.2012.02001.x

Chemes, H.E., Podesta, E. and Rivarola, M.A., 1976. Action of testosterone, dihydrotestosterone and 5alpha androstane 3alpha, 17beta diol on the spermatogenesis of immature rats. Biology of Reproduction, 14, pp. 332–338. https://doi.org/10.1095/biolreprod14.3.332

Chemineau, P., Malpaux, B., Brillard, J.P. and Fostier, A., 2007. Seasonality of reproduction and production in farm fishes, birds and mammals. Animal, 1, pp. 419–432. https://doi.org/10.1017/S1751731107691873

Chemineau, P., Malpaux, B., Delgadillo, J.A., Guerin, Y., Ravault, J.P., Thimonier, J. and Pelletier, J., 1992. Control of sheep and goat reproduction: use of light and melatonin. Animal Reproduction Science, 30, pp. 157-184. https://doi.org/10.1016/0378-4320(92)90010-B

Clemente, N., Orihuela, A., Flores-Pérez, I., Aguirre, V. and Valencia, J., 2013. Reproductive behaviour of Saint Croix and Suffolk rams at medium latitudes (19º N) during long days while being exposed to Suffolk ewes in seasonal anestrus. Archivos de Medicina Veterinaria, 45, pp. 67-70. https://dx.doi.org/10.4067/S0301-732X2013000100011

Clemente, N., Orihuela, A., Flores-Pérez, I., Aguirre, V., Ortiz, A., Solano, J. and Valencia, J., 2012. Reproductive activity of Suffolk ewes in seasonal anestrus after being exposed to Saint Croix or Suffolk rams. Journal of Applied Animal Research, 40, pp. 203-207. https://doi.org/10.1080/09712119.2012.658060

Courot, M., Hochereau-de-Reviers, M.T., Monet-Kuntz, C., Locatelli, A., Pisselet, C., Blanc, M.R. and Dacheux, J.L., 1979. Endocrinology of spermatogenesis in the hypophysectomized ram. Journal of Reproduction and Fertility. Supplement, 26, pp.165–173.

De Lucas-Tron, J., González, P.E. and Martínez, R.L., 1997. Estacionalidad reproductiva en ovejas de cinco razas en el Altiplano Central Mexicano. Técnica Pecuaria en México, 35, pp. 25–31. https://cienciaspecuarias.inifap.gob.mx/index.php/Pecuarias/article/view/620

Delgadillo, J.A., Vielma, J.I., Flores, J.A., Véliz, F.G., Duarte, G. and Hernández, H., 2008. La calidad del estímulo emitido por el macho determina la respuesta de las cabras sometidas al efecto macho. Tropical and Subtropical Agroecosystems, 9, pp. 39-45.

Dickson, K.A. and Sanford, L.M., 2005. Breed diversity in FSH, LH and testosterone regulation of testicular function and in libido of young adult rams on the southeastern Canadian prairies. Small Ruminant Research, 56, pp. 189–203. https://doi.org/10.1016/j.smallrumres.2004.06.002.

D'Occhio, M.J. and Brooks, D.E., 1982. Threshold of plasma testosterone required for normal mating activity in male sheep. Hormones and Behavior, 16, pp. 383–394. https://doi.org/10.1016/0018-506x(82)90047-2

Dufour, J.J., Fahmy, M.H. and Minvielle, F., 1984. Seasonal changes in breeding activity, testicular size, testosterone concentration and seminal characteristics in rams with long or short breeding season. Journal of Animal Science, 58, pp. 416-422. https://doi.org/10.2527/jas1984.582416x

García-Crespo, D., Justo, R., Sáez-López, C., Rodríguez, M. and Fernández-Pérez, L., 2008. Testosterone and metabolic regulation: Effects of experimental manipulations in rodents. Journal of Steroid Biochemistry and Molecular Biology, 112, pp.120–126. https://doi.org/10.1016/j.jsbmb.2008.09.012

Garza-Brenner, E., Sánchez-Dávila, F., Mauleón-Tolentino, K., Zapata-Campos, C.C., Luna-Palomera, C., Hernandez-Melendez, J., Gonzalez-Delgado, M. and Vázquez-Armijo, J.F., 2024. Systematic review of hormonal strategies to improve fertility in rams. Animal Reproduction, 21, e20240007. https://doi.org/10.1590/1984-3143-AR2024-0007

Gündogan, M., 2007. Seasonal variation in serum testosterone, T3 and andrological parameters of two Turkish sheep breeds. Small Ruminant Research, 67, pp. 312–316. https://doi.org/10.1016/j.smallrumres.2005.11.005

Hafez, E.S.E. and Hafez, B., 2013. Reproduction in farm animals (7th ed.). Wiley-Blackwell.

Hochereau?De Reviers, M.T., Copin, M., Seck, M., Monet?Kuntz, C., Cornu, C., Fontaine, I. and Elsen, J.M., 1990. Stimulation of testosterone production by PMSG injection in the ovine male: Effect of breed and age and application to males carrying or not carrying the “F” Booroola gene. Animal Reproduction Science, 23, pp. 21–32. https://doi.org/10.1016/0378-4320(90)90012-5

Hochereau-de Reviers, M.T., Monet-Kuntz, C. and Courot, M., 1987. Spermatogenesis and Sertoli cell numbers and function in rams and bulls. Journal of Reproduction and Fertility. Supplement, 34, pp. 101–114.

Ibarra, D., Laborde, D., Olivera, J., Van Lier, E. and Burgeño, J., 1999. Comparación de tres pruebas para medir la capacidad de servicio en carneros adultos. Archivos de Medicina Veterinaria, 31, pp. 189-196. https://dx.doi.org/10.4067/S0301-732X1999000200005

Hull, E.M. and Dominguez, J.M., 2019. Neuroendocrine regulation of male sexual behavior. Comprehensive Physiology, 9, pp. 1383–1410. https://doi.org/10.1002/j.2040-4603.2019.tb00093.x

Jawor, J.M., McGlothlin, J.W., Casto, J.M., Greives, T.J., Snajdr, E.A., Bentley, G.E. and Ketterson, E.D., 2006. Seasonal and individual variation in response to GnRH challenge in male dark-eyed juncos (Junco hyemalis). Hormones and Behavior, 50, pp. 762–772. https://doi.org/10.1016/j.yhbeh.2006.06.004

Johnson, L., Varner, D.D., Roberts, M.E., Smith, T.L., Keillor, G.E. and Scrutchfield, W.L., 2000. Efficiency of spermatogenesis: A comparative approach. Animal Reproduction Science, 60–61, pp. 471-480. https://doi.org/10.1016/S0378-4320(00)00108-1

Kafi, M., Safdarian, M. and Hashemi, M., 2004. Seasonal variation in semen characteristics, scrotal circumference and libido of Persian Karakul rams. Small Ruminant Research, 53, pp. 133–139. https://doi.org/10.1016/j.smallrumres.2003.07.007

Lakens, D., 2013. Calculating and reporting effect sizes to facilitate cumulative science: A practical primer for t-tests and ANOVAs. Frontiers in Psychology, 4, 863. https://doi.org/10.3389/fpsyg.2013.00863

Ledezma?Torres, R.A., Sánchez?Dávila, F., Luna?Palomera, C. and Vázquez?Armijo, J.F., 2023. La gonadotropina coriónica equina (eCG) modifica los niveles de testosterona, pero no la actividad reproductiva, en toros Holstein durante invierno. ITEA?Información Técnica Económica Agraria, 119, pp. 139-148. https://doi.org/10.12706/itea.2022.013

Lei, T., Yang, Y. and Yang, W.X., 2025. Luteinizing Hormone Regulates Testosterone Production, Leydig Cell Proliferation, Differentiation, and Circadian Rhythm During Spermatogenesis. International Journal of Molecular Sciences, 26, 3548. https://doi.org/10.3390/ijms26083548

Lincoln, G.A. and Davidson, W., 1977. The relationship between sexual and aggressive behaviour, and pituitary and testicular activity during the seasonal sexual cycle of rams, and the influence of photoperiod. Journal of Reproduction and Fertility, 49, pp. 267–276. https://doi.org/10.1530/jrf.0.0490267

Mantzoros, C.S., Georgiadis, E.I. and Trichopoulos, D., 1995. Contribution of dihydrotestosterone to male sexual behaviour. British Medical Journal, 310, pp. 1289–1291. https://doi.org/10.1136/bmj.310.6990.1289

Milczewski, V., Chahad-Ehlers, S., Spercoski, K.M., Morais, R.N. and Soccol, V.T., 2015. Quantifying the Effect of Seasonality on Testicular Function of Suffolk Ram in Lower Latitude. Small Ruminant Research, 124, pp. 68–75. https://doi.org/10.1016/j.smallrumres.2014.12.012

Montes-Garrido, R., Anel-Lopez, L., Riesco, M.F., Neila-Montero, M., Palacin-Martinez, C., Soriano-Úbeda, C., Boixo, J.C., de Paz, P., Anel, L. and Alvarez, M., 2023. Does Size Matter? Testicular Volume and Its Predictive Ability of Sperm Production in Rams. Animals, 13, 3204. https://doi.org/10.3390/ani13203204

Murphy, B.D., 2012. Equine chorionic gonadotropin: an enigmatic but essential tool. Animal Reproduction, 9, pp. 223-230.

O’Donnell, L. and Smith, L.B., 2026. Endocrinology of the Testis and Spermatogenesis. In: K.R. Feingold et al., (Eds.) Endotext. MDText.com, Inc.

Orihuela, T.A., 2014. La conducta sexual del carnero: Revisión. Revista Mexicana de Ciencias Pecuarias, 5, pp. 49-89. http://doi.org/10.22319/rmcp.v5i1.3217

Patil, S.R., Sonar, A., Londonkar, R., Patil, S.R. and Patil, S.B., 1998. Efficacy of exogenous gonadotropins on the maintenance of spermatogenesis in pethidine treated albino rats. Indian Journal of Physiology and Pharmacology, 42, pp. 509-514.

Perkins, A. and Roselli, C.E., 2007. The ram as a model for behavioral neuroendocrinology. Hormones and behavior, 52, pp. 70–77. https://doi.org/10.1016/j.yhbeh.2007.03.016

Plant, T.M. and Zeleznik, A.J., (Eds.). 2015. Knobil and Neill’s physiology of reproduction (4th ed.). Academic Press.

Price, C.A., Hudson, N.L. and McNatty, K.P., 1991. Plasma LH, FSH and testosterone concentrations in adult rams which were homozygous carriers or non-carriers of the Booroola fecundity gene. Journal of Reproduction and Fertility, 91, pp. 267–275. https://doi.org/10.1530/jrf.0.0910267

Rekik, M., Taboubi, R., Ben Salem, I., Fehri, Y., Sakly, C., Lassoued, N. and Hilali, M.E., 2015. Melatonin administration enhances the reproductive capacity of young rams under a southern Mediterranean environment. Animal Science Journal, 86, pp. 666–672. https://doi.org/10.1111/asj.12350

Rosa, H.J.D., Juniper, D.T. and Bryant, M.J., 2000. The effect of exposure to oestrous ewes on rams’ sexual behaviour, plasma testosterone concentration and ability to stimulate ovulation in seasonally anoestrous ewes. Applied Animal Behaviour Science, 67, pp. 293–305. https://doi.org/10.1016/s0168-1591(00)00086-1

Sanchez-Davila, F., Bernal-Barragan, H., Vazquez-Armijo, J.F., López-Villalobos, N., Ledezma-Torres, R.A., Grizelj, J., Garza-Brenner, E., Arce-Vasquez, N. and Palomera, C.L., 2020. Annual variation in reproductive parameters and sexual behaviour of Saint Croix rams in a semi-desert region in Mexico. Journal of Applied Animal Research, 48, pp. 499–506. https://doi.org/10.1080/09712119.2020.1830778

Servicio Meteorológico Nacional, 17 de julio del 2025. Comisión Nacional del Agua coordinación general del Servicio Meteorológico Nacional base de datos climatológica nacional. Estación 17037, Nombre; ESCUELA DE BIOLOGIA UAEM, Estado: Morelos, Municipio: Cuernavaca. https://smn.conagua.gob.mx/tools/RESOURCES/Normales_Climatologicas/Diarios/mor/dia17037.txt.

Smith, L.B. and Walker, W.H., 2014. The regulation of spermatogenesis by androgens. Seminars in Cell & Developmental Biology, 30, pp. 2–13. https://doi.org/10.1016/j.semcdb.2014.02.012

Tilbrook, A.J. and Clarke, I.J., 2001. Negative feedback regulation of the secretion and actions of gonadotropin-releasing hormone in males. Biology of Reproduction, 64, pp. 735–742. https://doi.org/10.1095/biolreprod64.3.735

Ungerfeld, R. and Bielli, A., 2008. 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. Reproduction in Domestic Animals, 43, pp. 400–402. https://doi.org/10.1111/j.1439-0531.2007.00922.x

Ungerfeld, R. and Silva, L., 2004. Ewe effect: endocrine and testicular changes in experienced adult and inexperienced young Corriedale rams used for the ram effect. Animal Reproduction Science, 80, pp. 251–259. https://doi.org/10.1016/j.anireprosci.2003.07.002

Ungerfeld, R., 2012. Treatment with an equine chorionic gonadotrophin single dose restored spermatozoa production in an azoospermic pampas deer (Ozotoceros bezoarticus) male: a case report. Reproductive Medicine and Biology, 12, pp. 65–68. https://doi.org/10.1007/s12522-012-0139-4

Ungerfeld, R., Clemente, N. and Orihuela, A., 2019. Treatments with eCG and courtship behaviour in rams during the breeding and the non-breeding seasons. Animal Production Science, 59, pp. 865-869. https://doi.org/10.1071/AN17728

Ungerfeld, R., Clemente, N., Bonjour, L. and Orihuela, A., 2014. Equine chorionic gonadotrophin administration to rams improves their effectiveness to stimulate anoestrous ewes (the “ram effect”). Animal Reproduction Science, 149, pp. 194–198. http://dx.doi.org/10.1016/j.anireprosci.2014.07.004

Walker, W.H., 2011. Testosterone signaling and the regulation of spermatogenesis. Spermatogenesis, 1, pp. 116–120. https://doi.org/10.4161/spmg.1.2.16956

Warita, K., Okamoto, K., Mutoh, K., Hasegawa, Y., Yue, Z.P., Yokoyama, T., Matsumoto, Y., Miki, T., Takeuchi, Y., Kitagawa, H., Sugawara, T. and Hoshi, N., 2008. Activin A and equine chorionic gonadotropin recover reproductive dysfunction induced by neonatal exposure to an estrogenic endocrine disruptor in adult male mice. Biology of Reproduction, 78, pp. 59–67. https://doi.org/10.1095/biolreprod.106.059857

Zaher, H.A., Alawaash, S.A. and Swelum, A.A., 2020. Effects of season and breed on the reproductive performance of sheep. Journal of Animal Reproduction and Biotechnology, 35, pp. 149-154. https://doi.org/10.12750/JARB.35.2.149




URN: http://www.revista.ccba.uady.mx/urn:ISSN:1870-0462-tsaes.v29i3.67942

DOI: http://dx.doi.org/10.56369/tsaes.6794

Copyright (c) 2026 Neftali Clemente Ovando

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.