The castration of male piglets remains a leading animal welfare issue for the global pork industry – and moves to end this age-old practice while retaining its undoubted benefits in terms of boar taint control and better behavior, remain a key question in many markets.

Ironically, stopping castration and switching to the production of entire boars is not only considered undesirable in many countries because of the increased risk of producing tainted meat and damaged carcasses; it also introduces a whole new set of animal welfare issues.

Castration vaccine 
Mature boars are aggressive, sexually active and can physically injure each other when housed together, especially at heavier weights. They are often not only a danger to themselves, but potentially to stockmen and shippers, as well. So clearly an alternative would be seen as useful by many.

In several parts of the world, an alternative is already being used successfully in commercial pig production units. The product works like a vaccine to block the action of the testes, and thus reduce both the levels of boar taint compounds in the meat and boar-like behavior.

Two doses are required: the first only primes the immune system; the second generates the immune response which produces the above effects. When given at the recommended times, the vaccine schedule allows the pig to grow as an intact male for most of its life, but without the risk of boar taint at slaughter, or boar-like behavior during the last weeks of finishing.

According to Jim Allison, senior director of global veterinary professional services, for the vaccine manufacturer, Pfizer Animal Health, the second castration irony is that the adoption of vaccination has actually been fastest in those markets where animal welfare is considered to be less of a driver for change.

“Many large integrated pig producers in Latin America, for example, have switched from castration to vaccination because of the performance and management benefits it brings to their operations, particularly the more efficient feed conversion and leaner, more valuable carcasses of vaccinated pigs compared to castrates,” he said.

Pig welfare issues
 The vaccine is approved in 63 different countries around the world, with more than 21 million doses used in Latin America alone, Allison noted. In 2011 the vaccine was approved in the United States and Canada and it is being increasingly used in key Asian markets.

Meanwhile, the pork chain in Europe, which has probably experienced more pressure to end castration than anywhere else in the world, is still looking for that elusive alternative.

With previous animal welfare issues, the European Commission has introduced new legislation to force pig producers to change the way they operate. This time, and for the first time for an important pig welfare issue, the EC has issued a Declaration that calls on stakeholders to end the practice of castration voluntarily by 2018.

Whether such a diverse group of individuals from so many different countries, and so many parts of the supply chain, can manage to meet that goal remains to be seen. The Commission’s welfare unit itself admits that this approach is something of an experiment.

Aggressive boar behavior
 A third irony is the fact that the country where the vaccine was originally conceived and developed, Australia, is essentially a non-castrating market, with some 70% of male pigs slaughtered intact, albeit at relatively light weights.

“Improving pork quality was the main driver for developing the vaccine, although welfare is now an increasing issue in Australia, with, for example, retail pressure to eliminate sow crates,” said Mr Allison.

“Excessive male behavior is also recognized as a potential welfare concern by the Australian RSPCA, Royal Society for the Prevention of Cruelty to Animals, which recognizes the use of vaccination as a solution to this problem.” Australian pig producers who use the vaccine are allowed to use the RSPCA’s ‘Paw of Approval’ logo.

Boar behavior becomes an increasing welfare problem with age, and there are also management considerations. Mixing of unfamiliar animals, disruption of hierarchy, for example by removing the heaviest animals and sending them to slaughter before the rest, and creating competition for resources, all stimulate aggression and fighting. The end of the fattening period and transport to the slaughter plant are critical times.

“Vaccinated boars spend more time feeding and less time fighting or mounting; in fact, they act much the same as castrates. This avoids the risk of injury and carcass damages that result from large animals fighting and continually mounting either each other or females if the sexes are co-penned,” explained Allison.

While the EU approved the addition of a behavior modification claim to the vaccine product authorization more than a year ago, this appears to have had little impact on the adoption of the product in the region.

EU pig industry concerns
 Consumer concern over welfare tends to go hand-in-hand with concern over consumer safety, and this is one of the barriers that appear to be slowing the broader adoption of vaccination in Europe.

Some observers believe the technology has been greatly misunderstood and misrepresented.

The fact that the vaccine works by reducing the levels of testicular hormone, testosterone, has been cited as the reason why it might not be acceptable to consumers in markets where hormone use in food animals is banned – even though there is no evidence on which to base such concerns. Of course it isn’t a hormone and does not act like a hormone – it actually works just like a conventional vaccine, by stimulating antibody production.

Experience shows that consumers have no interest or concern that pigs are vaccinated against PRRS or Mycoplasma. Physical castration, of course, also works by blocking the effects of testicular hormones – but no one worries that it may be a hormone itself.

“In fact, several market research studies among European consumers from a number of different countries have shown that they prefer the idea of vaccination rather than castration once they are given some explanation, and have no concerns about eating pork from vaccinated animals,” said Allison.

The pork industry is rightly protective of its image among consumers – it doesn’t want to take chances with the image of its products, in terms of quality or safety. Keeping consumers happy and reassured is also the number one priority for retailers.

Improving the welfare credentials of their suppliers fits with the desires of consumers in those markets where welfare is a concern. This was the motivation behind the Belgian retail chain Colruyt which last year stopped selling meat from castrated animals and switched its suppliers to vaccination. There has been no consumer reaction to this move and the vaccine has been used in Australia for almost 15 years without any consumer problems.

After more than three years of large-scale use, Latin America has had the same experience.

The raising of entire boars as an alternative to castration has attracted attention – chiefly in Europe. The UK and Ireland in particular are mostly non-castrating markets, but male pigs are slaughtered at a younger age and lower weights than is the usual practice in castrating markets.

Although this avoids welfare concerns over castration, producers lose out on the economic benefits of going to heavier weights. And even with early slaughter, the risk of boar taint is ever present.

Pig research continues 
On-going research is looking at the possibility of developing a ‘low taint’ genetic strain of pig, while maintaining the performance of existing lines. Other approaches being investigated include a cost-effective ‘low taint’ diet. Either way, it seems likely that a safety net in the form of a rapid taint detection system on the slaughter line would be necessary.

None of these prerequisites for entire boar production is anywhere near being achieved. In fact, there is still no broad agreement on which compounds are responsible for taint, or what the acceptable levels are. Until some form of standardization and harmonization is established – quality control assessment of taint is just not feasible. Such changes will also leave the unresolved the other issues of sexual and aggressive behavior in heavier boars, and an excessive carcass leanness for some uses.

Whatever happens, it appears as if the days of piglet castration are definitely numbered, on a global basis and it is ironic that a new technology primarily developed for its meat quality and production benefits could also provide an answer to one of the pig industry’s top animal welfare issues.

But presumably those who would like to see the end of this out-dated practice won’t be concerned whether alternatives, such as vaccination, are being adopted for welfare reasons or for the production benefits they bring. However, they may not be so happy with a switch to rearing entire males, which brings its own welfare issues.