After years of discussion, a revolution has started to take place in mainland Europe at the end of last year. A sector-wide agreement was reached to end the practice of physical castration in young piglets as from 2018. Until that time, solutions have to be applied now to relieve the animals' pain. For some, 2018 can't come quick enough, for others however, seven years may sound too short.
“Do you know how many potential consumers will be affected when one stinking pig makes it to the supermarket?” Dr Franz-Josef Stork, Topigs, drops a silence as to increase the impact of his words. “It will easily end up at more than a hundred plates. And if that happens, people will talk – ‘there’s stinking meat in this and that supermarket’. This easily indicates why a reduction to 1% is still 1% too many.”
When it comes down to selling boar meat, retailers and processors have been very careful to protect their image and market position. Boar meat, as is well known, may be tainted, effectively making the meat unsuitable for consumption and reducing its market value to zero. Thus it is not difficult to see that the idea of selling boar meat has not been a point of discussion until recently.
Selling boar meat, however, is something that all supermarkets in the European Union will be doing as from the year 2018. Representatives from many European organisations in the pork chain, from retailers, processors, breeders, veterinarians to welfare and retail organisations, agreed after several sessions in Brussels, Belgium, in November 2010 on a phasing out of the castration practice in seven years from now. As a first step towards this date, they agreed on the use of anaesthesia or prolonged anaelgesia as from 1 January 2012.
All parties involved acknowleged there is a common responsibility to solve the issue. Now, the question is how.
The complexity may best be illustrated with the defining question: What exactly is boar taint? A simple question, yet a difficult answer.
Boar taint is defined as an off-odour or -flavour in pork caused primarily by two compounds, skatole and androstenone, found in the backfat of male pigs. Androstenone is a steroid formed in the boar’s testes and skatole results from the breakdown of the amino acid tryptophan in dietary protein in the hindgut.
A large part of the definition, however, is a lot less certain and for several phenomena explanations still have to be found.• By far not every boar develops boar taint – if uncastrated, approximately 2%-5% develops boar taint;
• Levels of androstenone and skatole vary within breeds and from boar to boar;
• Humans are known to have different levels of tolerance to boar taint – some may feel like vomiting whereas others shrug;
• Female pigs may occasionally also produce tainted meat due to contact with excretion;
• Other compounds have been named to contribute to the occurrence of boar taint as well. Indole is often mentioned as one of these, although it has a very high correlation with skatole (also known as 3-methylindole).Finding a solution to the problem of boar taint equals dealing with a problem which is by far not fully understood. There are several ways to strongly reduce the influence of these compounds on meat. They are listed in the grey boxes in this article.
Before the total ban on castration can be reached in 2018, a lot of steps can be taken to reach that point in between. In the Netherlands and in Switzerland (non-EU but also committed to finding long-term solutions to solve the castration issue), the pork chain had already reached ‘temporal’ solutions.
In the Netherlands,as from December 2007, it was made mandatory to use carbon dioxide (CO2) in order to anaesthesise the piglets prior to castration. Announced as a breakthrough and agreed on with animal welfare intentions, the practice of this anaesthesia is still surrounded by many question marks as it is often found to be worse than the problem it’s supposed to solve – it’s labour intensive; the piglets may not always be 100% anaesthetised; they will still feel pain after waking up; and to top it all, there is the additional stress of the anaesthesia process, as piglets experience it as if they will suffocate.In Switzerland, isuflorane was suggested to be a good alternative. This gas however, comes with its own set of disadvantages as it can have a rather strong effect on adult humans as well. In addition, it’s a strong greenhouse gas.In Germany, not anaesthetics, but anaelgetics (painkillers) have been suggested to serve as a temporal solution. Boehringer Ingelheim’s Metacam was approved in the whole of the European Union for use as an anaelgetic to soothe post-operative pains.Last but not least, not every pig in the EU escapes the fate of physical castration. In markets where pigs need to grow until 150 kg or more, e.g. Italy, castration will remain part of the day-to-day business.
To be quite frank, it was about time a solution was found, says Dr Stork, wrapping up. “Many pig producers wanted to get rid of the practice. They don’t like castrating and it takes too long anyway.”
Still, there is a long way to go. Questions which will become relevant are: how will Europe monitor the boars to guarantee boar taint free pork? What will the system look like that everybody throughout the EU will accept? And who is going to pay for the new system? Or will it perhaps turn out to be more cost-effective, due to a lower FCR, as experiences from the UK indicate?Surely enough, the EU had seen all this coming. Europe launched two major programmes concerning the issue: one to get a clear overview of attitudes, practices and scientific progress (Pigcas) and a second to study alternatives to castration (Alcasde). Many of the solutions proposed there have also been included in this article. It will be 2018 in no time – and by then answers ought to be provided.
l than the hereditary traits – by taking out semen leading to male pigs through a sorting process. Since this process is expensive, Cardiff, UK-based biotech company Ovasort developed a method which may make it commercially interesting.The method developed is based on the presence of certain proteins on the surface of sperm cells. The company found that certain proteins are present only in X-bearing sperm, leading to female pigs. The technology exploits the concept of adding antibodies (protein binding molecules) to unsorted sperm cells which cause the cell-surface proteins to bind together, with the result of X-bearing cells becoming agglutinated, or clumped together.
Simple filtration then produces a population of Y-bearing (unagglutinated, ‘male’) cells that pass through the filter and a population of X-bearing cells that are trapped by the filter. Following filtration, the agglutinated X-bearing sperm can be deagglutinated if necessary to give samples enriched in either X- or Y-bearing sperm which can then be used in artificial insemination.
Obviously, using this method, efficiency may become more of an issue, as gilts, when raised, are less efficient in terms of lean meat, daily weight gain and feed conversion rate than their (entire) male counterparts.
For cattle, a product like this is estimated to be ready for the market within a year. The method is thought to reduce the cost of sexing semen to about a tenth of what it used to be. Trials will shortly be starting in Denmark at the Pig Research Centre (VSP).
Boar taint is a hereditary factor – that has been known for some time. Until recently, however, hardly anything had been done to use this knowledge to move into the zone of breeding boars, low on boar taint. Until now. At EuroTier, November 2010, animal breeding organisation Topigs, the Netherlands, announced the delivery of boars, proven low in boar taint. Using ongoing genetic selection, genomics and tracking, the organisation aims to offer pigs to customers which through its ancestry have a reduced risk of leading to boar taint. Dr Franz-Josef Stork, Topigs, said that his company began selecting and breeding boars with low boar taint (BTL boars) in 2007, when the Dutch pork chain had decided to jointly abandon current castration practices by 2015 at the latest. Encouraged by interest from e.g. German pork processor Tönnies, the organisation started working on it and the efforts paid off.
The detection of genetic traits, using genomics, is key when it comes down to selecting for BTL boars. “Levels of androstenone or skatole vary from boar to boar – their presence comes in a very wide range. Some have very high concentrations, some very low. Those with the highest concentrations usually produce boar taint. Our aim has been to reduce this variability through breeding – in other words, the amounts of androstenone, skatole and indole will be more or less similar in every boar – and below the level of boar taint detection.”
Special biomarkers will be delivered together with the boars. The eventual, non-castrated, male finishers being low in boar taint can thus be proven at slaughterhouses using SNP technology – which may prove individual pig monitoring rewarding.
Not only can boars be selected and delivered to the market with a guarantee to produce offspring which will be low in boar taint. Topigs also introduced the possibility to deliver breeding sows that will result in male pigs that are less likely to develop boar taint – although it will take somewhat longer to breed these gilts.
In Switzerland, a similar approach was taken by swine breeding organisation Suisag. It started a programme to develop a sire line which would create pigs low in boar taint. The result is called Premo – having a good FCR, good growth and good meat quality. By taking fat samples from young boar’s necks, the organisation was able to select for boars low in androstenone, skatole and indole. These data were combined with their actual growth pattern. Especially when it came down to androstenone levels, the new type of boars proved to be less of a risk.UK-based JSR Genetics initiated a project in 2006 to identify genetic markers, effective in reducing boar taint.
In cooperation with the University of Guelph, Canada, the company last year published results of research on the distribution in levels of androstenone and skatole of 300 uniquely identified entire boars, weighing over 110 kg and younger than 200 days. The boars comprised of 50 each from six different lines of pigs (three sire lines and three dam lines). Back fat was collected from each animal and levels of androstenone were analysed. Some of the breeds analysed showed extremely low incidence of boar taint whilst other breeding lines average fat skatole levels could decrease by 20% - 53% and fat androstenone by 26% - 61%. For the next stage of its research, the company will genotype all animals showing an incidence of boar taint for the SNP marker sets and then carry out association analysis to determine the effectiveness of each marker in the six different lines. These markers can then be used in breeding programmes to develop lines of pigs that are free of boar taint. Running along side the SNP analysis is confirmation analyses in commercial progeny to ensure the results at purebred level are translated into commercial pork production. Finding genetic markers is also key in research at the Institute for Genetics and Biotechnology at Aarhus University, Denmark. Headed by Henrik Hornshøj, a research project zooms in to reduce the undesired odour and flavour in pork. Finding one or a few of these genes that would pose boars at risk of boar taint would allow the development of a tool to avoid it. Hornshøj imagines that blood tests could be taken with all potential breeding boars.
Several feed ingredients are known to potentially have a positive effect on the development of boar taint. Adding chicory roots to pig feed was even presented as a promising alternative as boar meat from entire boars fed chicory-enriched meals was proudly presented at the Danish livestock show Agromek in 2009.The interest in the ingredient of chicory roots was spurred by researchers at Aarhus University, Denmark. Chicory roots contain the sugar inulin, which is known to inhibit the formation of skatole in the pigs’ hindgut. Results from studies that started in 2005 show that a mere week’s feeding with chicory roots immediately prior to slaughter reduces problems with boar taint. Two weeks of chicory feeding gives an even better result.
They concluded that the intestinal flora is altered, which also results in fewer intestinal parasites in the pigs. In addition, chicory roots were found to reduce the prevalence of swine dysentery and Lawsonia, which are two serious types of diarrhoeal diseases.
Attempting to get to know exactly how chicory influences skatole metabolism, scientists at Aarhus University and the Swedish University of Agricultural Science zoomed in onto the topic in 2010. By researching liver samples, they identified that chicory has an influence on mRNA expression of several enzymes, which are important for skatole metabolism. Researcher Dr Bo Ekstrand suggests: “I think it is the first time that someone shows that bioactive components in feed actually can affect the gene regulation in pigs in a practical feeding experiment.”Studies have also indicated that feeding lupins to the pigs may also reduce boar taint. A research in 2007 by Laurits Liedehøj Hansen (Aarhus University) and others indicated that skatole concentration in blood plasma and backfat in entire male and female pigs can be reduced to low levels with inclusion of 25% of blue lupins in the diet for seven or 14 days prior to slaughter. The amount, however, decreased animal performance.In addition, raw potato starch is also known to reduce skatole in plasma, faeces, fat and liver. Sugar beet pulp has been proven to do the same in faeces and blood.
A method in which processors could enhance the discussion would be to have a detection system in place which can guarantee identifying malodorous meat and remove these. There is quite some research on the development of a so-called ‘electronic nose’, which would enhance detection at the slaughterline.Until that time, slaughterhouses will have to find other solutions. In the 1990s, as indicated, British pig slaughterhouses faced the problem of non-castrating and therefore introduced the so-called hot wire test. Here a hot wire is stuck into the carcass’ fat, which makes it melt a little. This way, testers (often women as they are in general more sensitive to androstenone and skatole) can identify smelly carcasses. When carcasses are tested positive for boar taint, they are used for sausages or salamis.Europe is now following that same route.
Meat processor Vion Food Group, headquartered in the Netherlands but also a major player on the German meat market, announced in December 2010 it will start serving the Dutch market with fresh pork from non-castrated pigs. The initiative is the result of an earlier voluntary chainwide agreement in the Netherlands, formulated in the Declaration of Noordwijk, which will go into effect in 2015.
Elsewhere in Europe, e.g. in Germany, processors are now keen to consider non-castrated pigs as well. Germany’s largest cooperatively organised meat producer Westfleisch introduced a new welfare scheme in November 2010, called Aktion Tierwohl. Within this framework, the abandonment of piglet castration is one of the major requirements of farmers. In early 2011 the scheme was presented to the retail industry, and feedback appeared to be positive. Westfleisch aims to produce 650,000 pigs according to the welfare scheme with 350,000 pigs meeting the requirements at that moment.
As indicated, pork processor Tönnies expressed its interest in Topigs’ genetics programme and had already started working on a large scale with boars.
A series of articles, published earlier in Pig Progress, already explored the opportunities of non-physical castration, created by a two-shot vaccine. Pfizer Animal Health, developer of the two-shot vaccine Improvac, acquired access to the European market in 2009 after having introduced it in Australia some ten years earlier.After vaccination the testicular function of male pigs is temporarily suppressed and hence the development of boar taint is effectively prevented. The vaccine essentially triggers a male pig’s immune system to produce antibodies against ‘gonadotrophin releasing factor’ (GnRF), which usually stimulates the development and function of the testes. The first shot should be given after eight weeks of age; this does not have any direct effect and the pigs continue to grow like boars. The second shot, however, to be given four to six weeks prior to slaughter, does create a strong antibody response and the desired effect in male finisher pigs.
Extensive trials have indicated that use of the vaccine positively improves carcass quality in vaccinated pigs, as e.g. backfat layers have been observed to be less thick than in physically castrated males. Male pig behaviour has also been seen to improve, as trials have indicated a reduction in fighting or mounting in late finishing – hence the recent allowance to use the product in the EU for reduction of aggression as well. In addition, feed conversion rates in vaccinated pigs were observed to be better than in physically castrated pigs, as the animals continue to grow like boars until four to six weeks before slaughter.
The animal health company’s latest research, presented at IPVS 2010 in Vancouver, BC, Canada, focused on the life phase of the ‘castrate state’ of entires after the second injection. Jim Allison, director of veterinary professional services and new products marketing, said that in the four to six weeks after the second dose, a transitional phase will occur during which metabolism and carcass composition will gradually evolve into a castrate state. Acknowledging this can be a help in optimising management and nutrition.
In practice, drawbacks would include reservations from consumers, vaccinating twice and being totally dependent on one company. The company made a lot of effort to discover whether the market is ready for this approach and their market research seems to give the green light. The Belgian supermarket chain Colruyt has already announced to switch to selling pork from vaccinated boars.
One option to deal with the problem of boar taint is by developing a marketing system in which pigs are being sent to slaughter slightly earlier – to prevent the boar from maturing too much and developing boar taint. In Europe, this system is applied in Ireland, Portugal, parts of Spain, but the best example is the United Kingdom. There, piglet castration had largely disappeared by the mid-1980s. Apart from animal welfare reasons, the British Meat and Livestock Commission (MLC) noted that castration caused a lot of profit loss due to a poorer feed conversion rate, lower liveweight gain and carcass leanness.These days, about 80% of the British producers are members of the Assured British Pigs QA Scheme, which does not allow castration. Boars in Britain are typically sold to slaughterhouses at about 90 kg deadweight, although 80 kg is seen as ideal by processors – anything more than that is not paid for and from 100 kg even penalised.The British thus became accustomed to questions that may become very topical on the continent now as well, like: Should boars and gilts be kept apart or together? Do boars and gilts need different feed strategies?
Will boars display aggressive behaviour when held in groups?Dr Paul Toplis, Primary Diets, UK, explained in a presentation during the Raising Boarsseminar in the Netherlands, last year, that the majority of UK producers simply do not see the difference between entires and females – they just saw them as ‘pigs’. He added, however, that British veterinarians reported that ‘mounting and aggression’ was not a major issue. For some, however, it may have been a problem that some gilts had been found in-pig.
One comment to close off – it is often thought that boar taint would develop especially in those growers that have a slow growth rate. Studies by Prof Helen Miller, University of Leeds, however, indicated the contrary as she found that there is no relationship between boar taint and growth rate.