Skip to main content Accessibility help

Growth responses of entire and immunocastrated male pigs to dietary protein with and without ractopamine hydrochloride

  • T. Needham (a1), L. C. Hoffman (a1) and R. M. Gous (a2)


The interaction between dietary balanced protein, ractopamine (RAC) and Improvac (IMP) on the growth response of 120 individually penned male PIC© pigs was evaluated. The pigs entered the trial at 16 weeks of age and were assigned to 12 treatments using a 2×2×3 factorial design. Three balanced protein diets, formulated with standard illeal digestible lysine levels of 7.50 (low), 9.79 (medium) and 12.07 g/kg (high), were fed from 20 weeks. Improvac was administered at 16 and 20 weeks, the booster being given 4 weeks before slaughter. Ractopamine was supplemented at 10 mg/kg to the applicable treatments from 20 weeks. Live weight, backfat depth and food intake were measured on a weekly basis. Primary vaccination had no influence on the parameters measured. Immunocastration, RAC and higher protein diet treatments increased weight gain, but food intake was increased only with the use of IMP. Although weight gain increased in IMP-treated males, the increased feed intake resulted in their feed conversion efficiencies (FCE) being inferior to the intact controls. Feeding RAC only benefitted FCE when a high or medium protein diet was fed. Immunocastrates deposited more backfat after the booster vaccination than did entire males. Thus the cost of using RAC, IMP and of increasing dietary protein content needs to be weighed up against the additional revenue generated through the use of these interventions.


Corresponding author



Hide All
AOAC International 2002. Official method of analysis, 17th edition. Association of Official Analytical Chemists Inc, Arlington, VA, USA.
Apple, J, Rincker, P, McKeith, F, Carr, S, Armstrong, T and Matzat, P 2007. Review: meta-analysis of the ractopamine response in finishing swine. The Professional Animal Scientist 23, 179196.
Bauer, A, Lacorn, M and Claus, R 2009. Effects of two levels of feed allocation on IGF-I concentrations and metabolic parameters in GnRH-immunized boars. Journal of Animal Physiology and Animal Nutrition 93, 744753.
Boler, D, Kutzler, L, Meeuwse, D, King, V, Campion, D, McKeith, F and Killefer, J 2011. Effects of increasing lysine on carcass composition and cutting yields of immunologically castrated male pigs. Journal of Animal Science 89, 21892199.
Braña, D, Rojo-Gómez, G, Ellis, M and Cuaron, J 2013. Effect of gender (gilt and surgically and immunocastrated male) and ractopamine hydrochloride supplementation on growth performance, carcass, and pork quality characteristics of finishing pigs under commercial conditions. Journal of Animal Science 91, 58945904.
Brunius, C, Zamaratskaia, G, Andersson, K, Chen, G, Norrby, M, Madej, A and Lundstrӧm, K 2011. Early immunocastration of male pigs with Improvac® – effect on boar taint, hormones and reproductive organs. Vaccine 29, 95149520.
Claus, R, Lacorn, M, Danowski, K, Pearce, MC and Bauer, A 2007. Short-term endocrine and metabolic reactions before and after second immunization against GnRH in boars. Vaccine 25, 46894696.
Cronin, G, Dunshea, F, Butler, K, McCauley, I, Barnett, J and Hemsworth, P 2003. The effects of immuno- and surgical-castration on the behaviour and consequently growth of group-housed, male finisher pigs. Applied Animal Behaviour Science 81, 111126.
Dunshea, F, Colantoni, C, Howard, K, McCauley, I, Jackson, P, Long, K, Lopaticki, S, Nugent, E, Simons, J, Walker, J and Hennessey, DP 2001. Vaccination of boars with a GnRH vaccine (Improvac) eliminates boar taint and increases growth performance. Journal of Animal Science 79, 25242535.
Elanco Animal Health, Division of Eli Lilly and Company 2000. PayleanTM Technical Guide, Version 1.0. Prepared by R Muller (Technical Services). Elanco Animal Health, Division of Eli Lilly and Company, Indianapolis, IN, USA.
Ferguson, N, Gous, R and Emmans, G 1994. Preferred components for the construction of a new simulation model of growth, feed intake and nutrient requirements of growing pigs. South African Journal of Animal Science 24, 1017.
Food and Agriculture Organization of the United Nations (FAO) 2012. Fact sheet on Codex work on ractopamine. Retrieved on 8 December 2016 from
França, L, Silva, V, Chiarini-Garcia, H, Garcia, S and Debeljuk, L 2000. Cell proliferation and hormonal changes during postnatal development of the testis in the pig. Biology of Reproduction 63, 16291636.
Genstat 2015. Statistical Software, Release 14.2, VSN International Ltd, Hempstead, UK.
Hausman, D, Martin, R, Veenhuizen, E and Anderson, D 1989. Effect of ractopamine on insulin sensitivity and response to isolated rat adipocytes. Journal of Animal Science 67, 14551464.
Hinson, R, Wiegand, B, Ritter, M, Allee, G and Carr, S 2011. Impact of dietary energy level and ractopamine on growth performance, carcass characteristics, and meat quality of finishing pigs. Journal of Animal Science 89, 35723579.
Jaros, P, Bürgi, E, Stärk, K, Claus, R, Hennessy, D and Thun, R 2005. Effect of active immunization against GnRH on androstenone concentration, growth performance and carcass quality in intact male pigs. Livestock Production Science 92, 3138.
Lanferdini, E, Lovatto, P, Melchior, R, Orlando, U, Ceccantini, M and Poleze, E 2013. Feeding surgically castrated, entire male and immunocastrated pigs with different levels of amino acids and energy at constant protein to energy ratio with or without ractopamine. Livestock Science 151, 246251.
Lealiifano, A, Pluske, J, Nicholls, R, Dunshea, F, Campbell, R, Hennessy, D, Miller, D, Hansen, C and Mullan, B 2011. Reducing the length of time between slaughter and the secondary gonadotropin-releasing factor immunization improves growth performance and clears boar taint compounds in male finishing pigs. Journal of Animal Science 89, 27822792.
Lowe, B, Gerlemann, G, Carr, S, Rincker, P, Schroeder, A, Petry, D, McKeith, F, Allee, G and Dilger, A 2014. Effects of feeding ractopamine hydrochloride (Paylean) to physical and immunological castrates (Improvest) in a commercial setting on growth performance and carcass characteristics. Journal of Animal Science 92, 37273733.
Moore, K, Mullan, B, Kim, J and Dunshea, F 2016. Standardized ileal digestible lysine requirements of male pigs immunized against gonadotrophin releasing factor. Journal of Animal Science 94, 19821992.
Noblet, J, Shi, X and Dubois, S 1993. Energy cost of standing activity in sows. Livestock Production Science 34, 127136.
PIC© Nutrients Specification Manual 2011. Grow-finish specifications. Retrieved on 17 April 2016 from
Rikard-Bell, C, Curtis, M, Van Barneveld, R, Mullan, B, Edwards, A, Gannon, N, Henman, D, Hughes, P and Dunshea, F 2009. Ractopamine hydrochloride improves growth performance and carcass composition in immunocastrated boars, intact boars, and gilts. Journal of Animal Science 87, 35363543.
South African Code for the Welfare of Pigs 2014. Retrieved on 7 September 2014 from
Spurlock, M, Cusumano, J, Ji, S, Anderson, D, Smith, C, Hancock, D and Mills, S 1994. The effect of ractopamine on beta-adrenoceptor density and affinity in porcine adipose and skeletal muscle tissue. Journal of Animal Science 72, 7580.
USDA Foreign Agricultural Service 2016. Retrieved on 8 December 2016 from
Webster, M, Goodband, R, Tokach, M, Nelssen, J, Dritz, S, Unruh, J, Brown, K, Real, D, Derouchey, J, Woodworth, J, Goesbeek, C and Marsteller, T 2007. Interactive effects between ractopamine hydrochloride and dietary lysine on finishing pig growth performance, carcass characteristics, pork quality, and tissue accretion. The Professional Animal Scientist 23, 597611.
Weiler, U, Claus, R, Dehnhard, M and Hofäcker, S 1996. Influence of the photoperiod and a light reverse program on metabolically active hormones and food intake in domestic pigs compared with a wild boar. Canadian Journal of Animal Science 76, 531539.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

  • ISSN: 1751-7311
  • EISSN: 1751-732X
  • URL: /core/journals/animal
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed