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3. Solving the ‘boar taint’ problem

In many countries, the practice of castrating male piglets in the first few days of life is undertaken to eliminate the risk of ‘boar taint’ when pork is cooked. In the UK, castration of male piglets was discontinued many years ago. The issue has recently assumed a much higher profile in the debate about welfare standards in the pig industry and a number of countries have started to move away from current practices. Denmark has an extensive programme of research in place to identify effective alternatives to eliminate the risk of ‘boar taint’.

 

 
 Risk of ‘boar taint’

 

Castration is performed to remove an unpleasant odour that may occur when pork from male pigs is cooked and eaten. The odour, known as boar taint, is caused by the presence of the compounds skatole and androstenone in the meat.

Danish producers have been required to administer pain relief before the procedure takes place since June 2009.

A number of projects focused on boar taint, some government-funded, have been underway in Denmark for a number of years. A number of projects have been undertaken by the Danish Meat Research Institute (DMRI), the Danish Agriculture and Food Council (DAFC) and Aarhus University.

Susanne Støier, Director of Meat Technology at DMRI and Hanne Maribo, Chief Scientist at the Danish Pig Research Centre, which is part of DAFC, and are among Denmark’s small circle of boar taint experts. With the 2018 voluntary deadline in sight, both are keenly engaged in finding ways to screen and identify boar taint at the slaughterhouse and on the farm.

 
 Susanne Støier, Director of Meat Technology,
Danish Meat Research Institute

Skatole measurement at the abattoir

“For a number of years, a carcass sorting system has been running at Danish Crown’s abattoir in Ringsted, outside Copenhagen. Essentially, the amount of skatole in the neck fat of the entire male is measured and although the current equipment is more than 25 years old and can only measure skatole, Ringsted is the only slaughterhouse in Denmark able to conduct this test on line.

“Currently, therefore, DMRI is looking into ways of measuring both skatole and androstenone using an instrument-based solution, not a sensory-based one. We hope to have a suitable method using mass spectrometry equipment ready three to four years from now – a method that will work on a continuous basis, testing a high volume of samples,” explains Susanne Støier.

In the Netherlands and in Germany, some organoleptic testing takes place, and specially trained assessors smell the carcass on the production line. Sensory methods for detecting boar taint are, believes Susanne Støier, unsuitable for large-scale production.

“To our knowledge and experience, you cannot stand at a slaughter line, where there is a lot of noise and other distractions, and smell carcases for the presence of boar taint. A lab solution is preferable, including back fat sampling on the slaughter line followed by an organoleptic test in the laboratory, but this method is time-consuming and laborious and is only really suitable for special, smaller scale production, such as for the organic market. We tested whether it is possible for a panel to evaluate 200 samples during a working day, and it is. However it takes time to prepare all the samples, which is why this method is not really suitable for large-scale production of entire (non-castrated) males.”

Susanne and the team at the DMRI are also looking into how meat from entire males, i.e. meat with high levels of skatole and androstenone, can be used and not simply discarded.

“So far, we have highlighted some of the problems of using this meat and have some recommendations and solutions. Flavouring, marinating and smoking the meat are among the methods being looked at.”

Breeding and feeding

As far as the live pig is concerned, Hanne Maribo and colleagues are studying two main methods for reducing risk of odour - through breeding and through feeding.

“We have discovered that there are strong hereditary factors involved in both the presence of skatole and androstenone. But one of the issues that we also have to consider is the cost impact on the three established breeding parameters - daily weight gain, a higher level of lean meat and the number of live piglets on Day 5 (LG5). At the moment, as long as there is no “value” attributed to the absence of boar taint, we don’t breed to prevent it, but this could well change in the future as more entire male pigs are used for slaughter,” explains Hanne Maribo.

 
Hanne Maribo, Chief Scientist,
Danish Pig Research Centre

It is more profitable to produce entire males because of their efficient feed conversion and higher proportion of lean meat. Interestingly, the Duroc male does not have high levels of skatole.

“The breeding project that we’re currently involved in addresses androstenone levels,” says Hanne. “Our feeding project, on the other hand, is aimed at reducing skatole levels.”

Together with Aarhus University, Hanne and colleagues are currently looking into the positive effects of chicory and other sources of fibre on skatole presence and the effects of fermentation.

“Using dried chicory as a feed source is expensive over an extended period,” says Hanne. “We have looked at other sources and discovered that pure grain fed to the pig four days before slaughter also has a positive effect on skatole levels. I can foresee a scenario, therefore, where we breed to reduce androstenone and use modified feeding practices to prevent skatole.”

Vaccination

Although Belgium and the Netherlands use Improvac, a male hormone suppressing vaccine, to prevent boar taint and it has been approved for use in Norway, Sweden and the UK, it is not allowed by Danish slaughterhouses because of consumer concerns.

“We have conducted tests on boars that were vaccinated with Improvac and some still had boar taint. I don’t think the way forward – at least for Denmark – lies in this method,” says Hanne.

“Yes, the pressure is on to find a solution which will be ready for 2018, but I’m confident that using a combination of the methods currently being studied, we will have a solution to boar taint in place by the promised date.”