Effect of the biological castration vaccine (Improvac®) on sex hormones and reproductive organs of pigs in Vietnam https://doi.org/10.12982/VIS.2024.064

Main Article Content

Danh Cong Lai
Nam Minh Nguyen
Khanh Tran Doan Vinh
Hue Vo Thi
Phong Du Dai
Duy Tien Do


The Improvac® vaccine has been shown to improve growth performance, meat quality, and sexual behavior in swine herds in several countries. This study initially investigated the ability of this vaccine to control sex hormones and the development of reproductive organs in Vietnamese crossbred pigs (Yorkshire – Landrace x Duroc). A total of 45 male piglets were randomly divided into three groups: vaccinated at 12 and 18 weeks old, surgically castrated males at 7 days old, and entire males. Meanwhile, 40 female piglets were randomly assigned to one of two groups: those vaccinated at 12 and 16 weeks of age or entire females. Serum from experimental pigs was collected monthly before and after vaccination until slaughter (25 weeks of age). At the time of slaughter, reproductive organs were obtained to assess changes at the macroscopic and microscopic features. Anti-GnRH antibodies in the immunized male and female pigs increased dramatically and remained for several weeks following a booster shot, while serum levels of sex hormones were significantly lower than in the entire group (P<0.05). In addition, the reproductive organs of the immunized groups were negatively affected compared to the control groups. The male vaccinated group showed a significant reduction in the size of reproductive organs and irreversible disruption of spermatogenesis and testicular structure. The ovary and reproductive organs in the immunized female group revealed degradation in the size and ovarian follicle development. Taken together, the Improvac® vaccine can decrease sex hormones, thereby disrupting the development of reproductive organs in vaccinated male and female pigs.

Article Details

How to Cite
Danh Cong Lai, Nam Minh Nguyen, Khanh Tran Doan Vinh, Hue Vo Thi, Phong Du Dai, & Duy Tien Do. (2024). Effect of the biological castration vaccine (Improvac®) on sex hormones and reproductive organs of pigs in Vietnam: https://doi.org/10.12982/VIS.2024.064. Veterinary Integrative Sciences, 22(3), 933–947. Retrieved from https://he02.tci-thaijo.org/index.php/vis/article/view/268275
Research Articles


Andersson, K., Brunius, C., Zamaratskaia, G., Lundström, K., 2012. Early vaccination with Improvac®: effects on performance and behaviour of male pigs. Animal. 6(1), 87-95.

Bonneau, M., 2010. Accessory sex glands as a tool to measure the efficacy of immunocastration in male pigs. Animal. 4(6), 930-932.

Botha, A., Schulman, M., Bertschinger, H., Guthrie, A., Annandale, C.,Hughes, S., 2008. The use of a GnRH vaccine to suppress mare

ovarian activity in a large group of mares under field conditions.Wildl. Res. 35(6), 548-554.

Brewster, V., Nevel, A., 2013. Immunocastration with Improvac™ reduces aggressive and sexual behaviours in male pigs. Appl. Anim. Behav.Sci. 145(1-2), 32-36.

Brunius, C., Zamaratskaia, G., Andersson, K., Chen, G., Norrby, M.,Madej, A., Lundström, K., 2011. Early immunocastration of male pigs

with Improvac®–Effect on boar taint, hormones and reproductive organs. Vaccine. 29(51), 9514-9520.

Čandek-Potokar, M., Škrlep, M., Zamaratskaia, G., 2017. Immunocastration as alternative to surgical castration in pigs. Theriogenology. 6, 109-126.

Cheung, J., Bui, A.N., Younas, S., Edwards, K.M., Nguyen, H.Q., Pham,N.T., Bui, V.N., Peiris, M., Dhanasekaran, V., 2023. Long-term

epidemiology and evolution of swine influenza viruses in Vietnam. Emerg. Infect. Dis. 29(7), 1397-1406.

Claus, R., Lacorn, M., Danowski, K., Pearce, M.C., Bauer, A., 2007. Shortterm endocrine and metabolic reactions before and after second immunization against GnRH in boars. Vaccine. 25(24), 4689-4696.

Cronin, G., Dunshea, F., Butler, K., McCauley, I., Barnett, J., Hemsworth, P.,2003. The effects of immuno-and surgical-castration on the behaviour and consequently growth of group-housed, male finisher pigs. Appl.Anim. Behav. Sci. 81(2), 111-126.

Dalmau, A., Velarde, A., Rodríguez, P., Pedernera, C., Llonch, P., Fàbrega,E., Casal, N., Mainau, E., Gispert, M., King, V., 2015. Use of an

anti-GnRF vaccine to suppress estrus in crossbred Iberian female pigs. Theriogenology. 84(3), 342-347.

Earl, E.R., Waterston, M.M., Aughey, E., Harvey, M.J., Matschke, C.,Colston, A., Ferro, V.A., 2006. Evaluation of two GnRH-I based

vaccine formulations on the testes function of entire Suffolk cross ram lambs. Vaccine. 24(16), 3172-3183.

Einarsson, S., Andersson, K., Wallgren, M., Lundström, K., RodriguezMartinez, H., 2009. Short-and long-term effects of immunization

against gonadotropin-releasing hormone, using Improvac™, on sexual maturity, reproductive organs and sperm morphology in male

pigs. Theriogenology. 71(2), 302-310.

Einarsson, S., Brunius, C., Wallgren, M., Lundström, K., Andersson, K., Zamaratskaia, G., Rodriguez-Martinez, H., 2011. Effects of early

vaccination with Improvac® on the development and function of reproductive organs of male pigs. Anim. Reprod. Sci. 127(1-2), 50-55.

Elhay, M., Newbold, A., Britton, A., Turley, P., Dowsett, K., Walker, J.,2007. Suppression of behavioural and physiological oestrus in the

mare by vaccination against GnRH. Aust. Vet. J. 85(1‐2), 39-45.

Esbenshade, K., Ziecik, A., Britt, J., 1990. Regulation and action of gonadotrophins in pigs. J. Reprod. Fertil. Suppl. 40, 19-32.

Fàbrega, E., Velarde, A., Cros, J., Gispert, M., Suárez, P., Tibau, J., Soler, J.,2010. Effect of vaccination against gonadotrophin-releasing hormone, using Improvac®, on growth performance, body composition,behaviour and acute phase proteins. Livest. Sci. 132(1-3), 53-59.

Font-i-Furnols, M., Gispert, M., Soler, J., Diaz, M., Garcia-Regueiro, J., Diaz,I., Pearce, M., 2012. Effect of vaccination against gonadotrophinreleasing factor on growth performance, carcass, meat and fat qualityof male Duroc pigs for dry-cured ham production. Meat. Sci. 91(2),148-154.

Gispert, M., Oliver, M.À., Velarde, A., Suarez, P., Pérez, J., i Furnols, M.F.,2010. Carcass and meat quality characteristics of immunocastrated male, surgically castrated male, entire male and female pigs. Meat.Sci. 85(4), 664-670.

Hernández-García, F.I., Duarte, J.L., Pérez, M.A., Raboso, C., del ROSARIO, A.I., Izquierdo, M., 2013. Successful long-term prepubertal immunocastration of purebred Iberian gilts reared in extensive systems. In 8th International congress on mediterranean pig,

Ljubljana, Slovenia, 10–12 October 2013, pp. 123-126.

Janett, F., Gerig, T., Tschuor, A., Amatayakul-Chantler, S., Walker, J.,Howard, R., Bollwein, H., Thun, R., 2012. Vaccination against

gonadotropin-releasing factor (GnRF) with Bopriva significantly decreases testicular development, serum testosterone levels and

physical activity in pubertal bulls. Theriogenology. 78(1), 182-188.

Karaconji, B., Lloyd, B., Campbell, N., Meaney, D., Ahern, T., 2015. Effect of an anti‐gonadotropin‐releasing factor vaccine on sexual and aggressive behaviour in male pigs during the finishing period under A ustralian field conditions. Aust. Vet. J. 93(4), 121-123.

Kubale, V., Batorek, N., Škrlep, M., Prunier, A., Bonneau, M., Fazarinc, G.,Čandek-Potokar, M., 2013. Steroid hormones, boar taint

compounds, and reproductive organs in pigs according to the delay between immunocastration and slaughter. Theriogenology. 79(1), 69-80.

Lestari, L.S., Kitagawa, K., Tsugeuma, M., Kibushi, M., Deguchi, Y.,Shirotozaki, M., Sasahara, R., Tau, S., Tamada, H., Kawate, N., 2018.

PF-33 Effects of GnRH vaccine, Improvac®, on Oestrus, Ovarian Activity and Growth in Japanese Black Fattening Beef Heifers. In

Proceedings of the 20th FAVA & the 15th KIVNAS PDHI Hemera Zoa, Bali, Indonesia, 1-3 November 2018.

Lueders, I., Hildebrandt, T.B., Gray, C., Botha, S., Rich, P., Niemuller, C., 2014. Supression of testicular function in a male Asian elephant

(Elephas maximus) treated with gonadotropin-releasing hormone vaccines. J. Zoo. Wildl. Med. 45(3), 611-619.

Martinez-Giménez, J., Ferrero-Vicente, L., Feltrer-Rambaud, Y., 2021. Effects of a gnrh vaccine (improvac®) on patagonian (Otaria byronia) and california sea lions (Zalophus californianus). J. Zoo. Wildl. Med.52(2), 721-725

Mitjana, O., Bonastre, C., Tejedor, M.T., Garza, L., Latorre, M.Á.,Moreno, B., Falceto, M.V., 2020. Immuno-castration of female

and male pigs with anti-gonadotrophin releasing hormone vaccine: Morphometric, histopathological and functional studies of the

reproductive system. Anim. Reprod. Sci. 221, 106599.

Morales, J., Martinell, M.G., Hortos, M., Pérez, J., Suárez, P., Noguera, C.P., 2010. Evaluation of production performance and carcass quality characteristics of boars immunised against gonadotropinreleasing hormone (GnRH) compared with physically castrated male, entire male and female pigs. Span. J. Agric. Res. 8(3), 599-606.

Oliver, W., McCauley, I., Harrell, R., Suster, D., Kerton, D., Dunshea, F.,2003. A gonadotropin-releasing factor vaccine (Improvac) and porcine somatotropin have synergistic and additive effects on growth performance in group-housed boars and gilts. J. Anim. Sci. 81(8),1959-1966.

Pop, M.G., Crivii, C., Opincariu, I., 2018. Anatomy and function of the hypothalamus. In: Baloyannis, S.J., Gordeladze, J.O. (Ed.),

Hypothalamus in health and diseases. Available online: https://www.intechopen.com/chapters/63258.

Quiniou, N., Monziols, M., Colin, F., Goues, T., Courboulay, V., 2012. Effect of feed restriction on the performance and behaviour of pigs immunologically castrated with Improvac®. Animal. 6(9), 1420-1426.

Rydhmer, L., Lundström, K., Andersson, K., 2010. Immunocastration reduces aggressive and sexual behaviour in male pigs. Animal. 4(6), 965-972.

Schütz, J., Rudolph, J., Steiner, A., Rothenanger, E., Hüsler, J., Hirsbrunner,G., 2021. Immunization against Gonadotropin-Releasing Hormone in Female Beef Calves to Avoid Pregnancy at Time of Slaughter. Animals. 11(7), 2071.

Schwarzenberger, F., Krawinkel, P., Jeserschek, S.M., Schauerte, N., Geiger, C., Balfanz, F., Knauf‐Witzens, T., Sicks, F., Martinez Nevado, E.,Anfray, G., Hein, A., Kaandorp-Huber, C., Marcordes, S., Venshøj,B., 2022. Immunocontraception of male and female giraffes using the GnRH vaccine Improvac®. Zoo. Biol. 41(1), 50-64.

Soede, N., Langendijk, P., Kemp, B., 2011. Reproductive cycles in pigs. Anim. Reprod. Sci. 124(3-4), 251-258.

Sofikitis, N., Giotitsas, N., Tsounapi, P., Baltogiannis, D., Giannakis, D., Pardalidis, N., 2008. Hormonal regulation of spermatogenesis and spermiogenesis. J. Steroid. Biochem. Mol. Biol. 109(3-5), 323-330.

Stratakis, C.A., Chrousos, G.P., 1997. Hypothalamic hormones. In:Endocrinology. Springer, pp. 185-209.

Ülker, H., Yılmaz, A., Karakuş, F., Yörük, M., Budağ, C., deAvila, D.M., Reeves, J.J., 2009. LHRH fusion protein immunization alters

testicular development, ultrasonographic and histological appearance of ram testis. Reprod. Domest. Anim. 44(4), 593-599.

Vázquez, N.A., Aguilar, N.C.V., Brenner, E.G., Dávila, F.S., Trejo, A.M.,Ramírez, M.C., Barragán, H.B., 2020. PSVII-30 Growth performance,

and serum concentration of testosterone of male and female pigs immunocastrated with a GnRH analogue, fed wet low-protein diets. J.Anim. Sci. 98(4), 463.

Xue, Y., Zheng, W., Zhang, F., Rao, S., Peng, Z., Yao, W., 2019. Effect of immunocastration on growth performance, gonadal development and carcass and meat quality of SuHuai female pigs. Anim. Prod. Sci. 59(4), 794-800.

Zamaratskaia, G., Andersson, H., Chen, G., Andersson, K., Madej, A.,Lundström, K., 2008. Effect of a Gonadotropin‐releasing Hormone

Vaccine (ImprovacTM) on Steroid Hormones, Boar Taint Compounds and Performance in Entire Male Pigs. Reprod. Domest. Anim. 43(3),351-359.

Zoels, S., Reiter, S., Ritzmann, M., Weiß, C., Numberger, J., Schütz, A., Lindner, P., Stefanski, V., Weiler, U., 2020. Influences of

immunocastration on endocrine parameters, growth performance and carcass quality, as well as on boar taint and penile injuries. Animals. 10(2), 346.