Castration in Pigs

Pork is the most widely consumed meat across the world and nearly 1 billion pigs are farmed every year to satisfy demand. The top three pork producing regions are China, European Union (EU) and the United States of America. The majority of male piglets born in these countries are surgically castrated before they are a week old. It is widely accepted, due to behavioural and physiological indicators, that castration is painful; however, castration is largely performed without pain relief, that is, anaesthesia and analgesia are rarely used, which is a welfare concern.

Castration of piglets occurs for management reasons (to reduce aggression, lessen unwanted mounting behaviour, and prevent unplanned pregnancies) and to decrease the probability of ‘boar taint’. Boar taint is present in some carcases due to the presence of skatole (a strong-smelling amine compound, produced  during protein decomposition in the intestine) and androstenone (a pheromone in boars) and may be perceived by some consumers as unpleasant. Un-castrated, entire male pigs are most likely to be effected by boar taint (although some female pigs are also effected) and animals reared in production systems that slaughter animals at higher weights are also more likely to experience boar taint since older animals may reach puberty before slaughter and there is some association between puberty and taint.

Sensitivity to boar taint varies between people and there are also differences between countries as to its acceptability (eg consumers in France, Germany and Spain find boar taint highly unacceptable whilst consumers in the UK less so). Consequently, the percentage of male pigs castrated in individual countries within Europe varies widely – in the UK (where pigs are slaughtered at lighter weights and there is less consumer aversion to boar taint), virtually no piglets are castrated, however, in France and Germany (where pigs are killed at higher weights and there is a marked consumer aversion to boar taint), then over 90% of piglets are castrated.

Within Europe there is a move towards raising pigs without castration. In November 2010, a 'European Declaration on alternatives to surgical castration of pigs'(1) was signed by many key groups within the pig industry. The Declaration centred around: understanding, detecting and reducing boar taint more effectively, and investigating production systems and management of entire males during rearing, transport and at slaughter to reduce sexual and aggressive behaviours. Importantly, Signatories agreed that, as of 01 January 2012, all castrated piglets would be treated with prolonged analgesia and/or anaesthesia and that by 1 January 2018 castration may not be performed at all (although castration will still be permitted in production systems registered under “traditional specialties guaranteed” or with “geographical indications”).

Before the signing of the Declaration, approximately 100 million male piglets reared in the EU were castrated without anaesthesia or analgesia (this equates to 70% or the 125 million male piglets reared in the EU). A progress report in 2014 (2) indicates that the desired outcome of all castrated piglets receiving appropriate analgesia/anaesthesia by 2012 was not achieved, but it does show that much progress has been made. Countries that previously only raised castrated males are beginning to manage entire male systems and where piglets are castrated, greater numbers are castrated with some level of analgesia or anaesthesia. Difficulties arise in the accepted best method and practicalities of using anaesthesia and/or analgesia and there is still much to be learnt about boar taint and the associated socio-cultural and marketing barriers.

Significantly, the report highlighted the need for greater national collaboration and research. Research is key if pig welfare is to be improved in this area.

Examples of UFAW supported projects in pig welfare:

In 2015 UFAW supported Dr Pierpaolo Di Giminiani, a research associate at Newcastle University, in travelling to the United States of America to establish a partnership in pig welfare research between the School of Agriculture Food and Rural Development at Newcastle University, and the College of Food, Agricultural, and Environmental Sciences at Ohio State University, with a particular focus on exchange of expertise on the most relevant methodologies employed in the assessment and in the management of painful conditions resulting from modern pig farming systems.

Another project supported by UFAW aims to investigate the validation of pain biomarkers in pigs, specifically when considering lameness, but, once validated, pain and lameness biomarker data have the potential to be included within breeding selection objectives – both in the genetic programme for population improvement and in the on-going screening of animals sold to production herds – and could bring significant benefits to pig welfare.

Selected papers on pig castration published in the UFAW Journal, Animal Welfare:

Vanhonacker, F; Verbeke, W; Tuyttens, FAM. 2009. Belgian consumers’ attitude towards surgical castration and immunocastration of piglets. Animal Welfare, V18(4), pp372-380. UFAW.

Prunier, A; Bonneau, M; von Borell, EH; Cinotti, S; Gunn, M; Fredriksen, B; Giersing, M; Morton, DB; Tuyttens, FAM; Velarde, A. 2006. A review of the welfare consequences of surgical castration in piglets and the evaluation of non-surgical methods. Animal Welfare, V15(3), pp 277-289. UFAW.

References:

  1. European Declaration on alternatives to surgical castration of pigs. Voluntary declaration signed by key stakeholders in the pig industry in December 2010. For further information, please visit the following website, available at: http://ec.europa.eu/food/animal/welfare/farm/initiatives_en.htm
  2. First progress report from the European declaration on alternatives to surgical castration of pigs (16/12/2010). Report from the Expert Group on ending the surgical castration of pigs (2012-2014). October 2014. Available at: http://ec.europa.eu/food/animals/welfare/practice/farm/pigs/castration_alternatives/index_en.htm.