The surgical castration of male piglets in pig farming is often presented as having no alternative. This extremely painful intervention is usually justified with the prevention of the risk of the so-called boar taint. Boar taint occurs extremely rarely and only when the meat is heated. There are also several alternatives to surgical castration. In addition to boar fattening and immunocastration (a vaccination against boar taint), surgical castration under general anaesthesia and post-operative analgesia is also an intermediate option. All three alternatives are acceptable from an animal welfare point of view. There are also new alternatives arising with the progress of technology, like genetic castration. On the other hand, methods that do not adequately eliminate pain or consciousness, such as local anaesthesia, are not acceptable.
The male pigs are raised and fattened without being castrated. The animals are more active and there may be increased activity in the barn. The housing conditions must therefore be adapted to the special needs of the boars. Good management is required. In the UK, Ireland and some other countries, boars are traditionally raised without being castrated at all. In other countries, there are already some companies that have switched to boar fattening, but not many.
Immuno-castration – vaccination against boar taint
A vaccination is carried out two to three times, which suppresses the testicular activity of the boars. The testicles grow less and there is no boar taint. The vaccine is applied with a safety injector. An unintentional self-injection, which could also endanger users, is practically impossible. Immuno-castration is not a hormonal treatment, and the pork therefore does not contain hormones. This is very important for consumers to know as it can otherwise lead to false consumer information.
New Zealand and Australia are countries that have successfully used immuno-castration since 1998. It has also been carried out extensively in Brazil since 2005. The preparation has been approved as a vaccine in Switzerland since 2007 and in the EU since 2009. It is used primarily in Belgium
Gene editing is currently not permitted across the European Union, but that might change in the near future. There are constant new developments and research to improve animal welfare, and countries outside of EU are already working towards the implementation of genetic castration to prevent the unnecessary suffering of pigs during castration.
There are many possible ways genes can be edited to castrate the pigs and therefore prevent the boar taint. One option seems to be by suppressing the male phenotype where the testes do not develop, even though the pigs’ genotype is male. Another version is to destroy the male chromosome in the sperm and therefore making all the piglets in the litter female, or by removing the genes in male piglets that cause adolescence. The latter requires the use of hormone injection, which traditionally does not go well with the public perception of safe animal products1.
Whichever method of genetic castration is used, more research must be done about it to ensure animal welfare. It must be ensured that no abuse of gene editing takes place and one must be aware that this is still manipulation of an animals’ integrity.
Inhaled anaesthesia (isoflurane) and pain treatment
With this method, the piglets are anaesthetised through an inhalation mask with the anaesthetic called isoflurane. In Germany and Austria, it is only allowed to be performed by a veterinarian. In Switzerland, on the other hand, farmers trained in it may use this form of stunning in piglets. Pain medication must be given in advance in order to relieve the post-pain of the procedure after waking up. Loss of consciousness by isoflurane begins after one minute at the latest.
If companies cannot or do not want to go without surgical castration, this anaesthetic method is an acceptable alternative from an animal welfare point of view. The prerequisite is that the anaesthetic masks are adapted to the age of the animals so that the required anaesthetic depth can be achieved. Also, the animals should not be brought upside down into the inhalation mask, but in the best case in the normal position (legs down) or on the back. Isoflurane is a potentially toxic substance and has therefore been in discussion of whether it is safe enough under farm conditions (without a ventilation system - as it is available in veterinary clinic surgery rooms) or not.
General injection anaesthesia and pain treatment - an acceptable alternative
With injection anaesthesia, a mixture of ketamine and azaperone is injected into the piglet. The application must be carried out by a veterinarian. The injection anaesthetic can be administered intravenously (into the vein - here into the ear vein) or intramuscularly (into the muscle). In any case, the piglets for this method should be at least 14 to 21 days old, so that a possibly longer sleeping and waking up phase does not lead to health problems. If the piglets are too young or the dosage is too high, a long sleep phase can lead to them losing weight because they do not suckle during this time. However, with this method, it is not necessary to castrate the piglets in the first week, therefore farmers can wait until the piglets have gained weight and are more fit. Pain medication must be given to be effective post-surgically, as anaesthesia is not pain alleviating.
- Inhalation with the anaesthetic medium CO2
The CO2 anaesthetic should be rejected for animal welfare reasons. This lies in the extremely stressful induction phase - the CO2 causes attacks of suffocation, breathing disorders and negative reactions of the animals. Added to this are the insecure restrains of the anaesthetic machines and the relatively high mortality rate of animals.
- Local anaesthesia (the so-called 'fourth way')
With local anaesthesia, a local anaesthetic is injected into both testes and the spermatic cord about ten minutes before the procedure. This often requires several injections, which are extremely painful and stressful for the animals. Experts assume, that the animals suffer pain similarly when they are stabbed into their testicles, as if they were castrated without anaesthesia. The effect of pain relief from the agent is also assessed as insufficient for testicular removal. The term 'fourth way' was created because three alternatives (boar fattening, immuno-castration, or castration under general anaesthesia) have been discussed as acceptable alternatives. Local anaesthesia is not yet a recognised, legal procedure in most countries, even though the agricultural industry is lobbying for its legalisation. However, nothing would improve for the animals and the castration procedure would remain extremely painful and stressful for the animals.
- Exclusive use of pain relievers
Castration without anaesthesia, only with pain medication is not acceptable from an animal welfare point of view, because the greatest pain is not eliminated during the procedure.