Fact sheets on ending surgical boar castration

The European Commission produced educational materials to help farmers, meat processors and retailers transitioning away from surgical castration of pigs, including factsheets on ending surgical castration and methods to detect boar taint. The PDF’s below are a schematic representation of both subjects.

In the first PDF, techniques and best practices for slaughterhouses for the detection of boar taint are presented. One of the most successful methods is the human nose method.

In the second PDF, the Commission shares a success story about a leading Dutch slaughterhouse that developed its own boar taint detection technique, based on the human nose method. With over 10 years of experience in producing boar meat, this EU market leader operates in several countries, slaughtering thousands of male pigs each week.

Open PDF 1
Open PDF 2

Researcher Hanne Maribo: reducing boar taint through feed

Hanne Maribo is a senior scientist at the SEGES Pig Research Centre, part of the Danish Agriculture & Food Council. Maribo worked in pig research for 30 years. She started her studies in Animal Science and Economics, and received her Phd at the Meat Research Institute.

Can you tell something about your current research?
“During the last ten years I have worked on feed for male pigs to reduce boar taint and increase productivity. Especially the use of fiber sources and pure grains as well as increasing energy and protein levels in the diet.”

How does feed reduce skatole levels?
“The research results show that adding chicory to feed reduces the skatole content of up to approximately 60%. Reducing skatole content by using chicory three days before slaughter compared to two weeks before slaughter gives the same results on the skatole level but is much cheaper. This is due to the fact that the halftime of skatole in fat equals eleven hours. Farms with a delivery section can thus limit the time for which the more expensive feed has to be applied.”

Are there any other feed sources that also affect skatole content?
“Yes, both sugar beet pulp pellets, Jerusalem artichoke and pure grain have a reducing effect on skatole. Using sugar beet for two weeks resulted in a 50% lower skatole content. For pure grain we observed reductions in skatole content of 30%. This is quite remarkable given the already low skatole levels we had in the control group. The principle behind this is that using pure grain reduces tryptophan in the diet, and thereby the substrate for producing skatole.”

And what about the feed cost?
“Using chicory results in 1 euro higher feed cost per pig. For sugar beet and pure grain the increase in feed cost per pig equals €1-2 respectively. When we learn more about the halftime, farmers can use the additives efficiently.”

What would you do if you were a pig farmer who does not castrate the piglets?
“As a pig farmer raising entire male pigs I would use feed with extra energy and protein with split sex rearing. And if there is a penalty on boar taint prevalence, I would use feed with fibres (chicory or sugar beet) or pure grain only during the last few days before slaughter. The age of the slaughter pigs and the breed is also important. Androstenone increases with age/weight and by choosing fathers with a low breeding value for androstenone you can reduce androstenone in the offspring. There are many ways in which skatole levels can be reduced, of which feed is an important factor.”

Read more about feeding techniques on our topic page.

“I have always considered raising boars as a good thing, both for the animal as for the farmer.”

Rudolf Raymakers is 64 years old. He is a vet specialised in pigs and co-owner of the Veterinary Centrum in Someren, The Netherlands.

How did you start your career?
“I graduated in 1982 on a Friday, and the next Monday I started to work at the Veterinary Centrum Someren. During my whole career of 38 years I was a member and co-owner of the Veterinary Centrum Someren, which is located in the South of the Netherlands, close to Germany and Belgium. The well equipped Equine Clinic provides services for international cliënts directly or via referring veterinarians. I started to specialize in pigs in 1991, after the outbreak of the porcine reproductive and respiratory syndrome (PRRS).”

What has changed since you started working?
“In those early years the Dutch pig farmers were very reluctant to switch to raising entire male pigs. Farmers were afraid of the risk of boar tainted carcasses. But ten years ago the discussion on ending castration started in the Netherlands. Animal welfare became more and more a topic in the news. First we started with castrating pigs under anaesthesia. But after a while farmers also started to think about raising boars. They looked at the situation in Spain and the United Kingdom where producing entire male pigs is normal. Farmers also realized that boars have advantages in terms of efficiency and feed conversion ratio. Especially in the second part of the fattening period, boars can grow very fast.”

What is your advice for farmers switching to entire male pig production? 
“Over the years, I have guided tens of pig farmers with boars. In the beginning we got signals that the boars were restless and that mounting behaviour occurred. This happens indeed. My advice – and with good results – has always been to keep the litter together as much as possible.” 

Why do you recommend keeping the litter together? 
“Mounting behaviour is less in mixed groups. And off-course the feed conversion and growth is less, because it is more difficult to utilize the growth potential of the boars. The health advantage of mixed sexed groups is very substantial. For me this was a clear example of a so called ‘best practice’.”

What are other aspects that need attention in entire male pig production?
“Another very important management aspect comes along when the boars enter the fattening compartment at 25-30 kg. They are often quite lean at this weight, and it is very important that the feed intake is high enough. In a environment in which the animal feels safe, with group members they already know, this process is much easier.”

“Taking these learnings into account, I  have come to the conclusion that raising boars is a good thing, both for the animal as for the farmer.”

Pig farmer Georg Freisfeld

The wellbeing of our pigs is at the heart of our daily routine” 

Georg Freisfeld runs an arable and pig farm together with his wife Katrin. Their farm Freisfeld Hof is located in the southern part of Munsterland in the municipality Ascheberg, North Rhine Westphalia. They house close to 2.000 fattening pigs, next to the 75 hectares of arable land and 7 hectares of forest. 

Since when are you a pig farmer?

I am a pig farmer since 1997. Before this I obtained my BSc in Agriculture. 

What does your farm look like?

Nearly 2000 fattening pigs have their home in our farm. We do not breed piglets, as we have a long term relationship to a sow farmer. In addition to the pigs we grow our crops and corn on 75 hectares of arable land. We are a member of the German Producer Cooperation Westfalen. As from May 2015, we participate in the so called Initiative Tierwohl. The wellbeing of our pigs is at the heart of our daily routine.

When did you start working with entire male pigs? 

We started rearing entire male pigs in November 2008. The retail organisation wanted to test selling  meat from entire male pigs. At the same time Zoetis (formerly Pfizer) wanted to have their new vaccine tested for European approval in our farm. These two events led to our decision to change our farm practices. 

How did you experience this change in the beginning?

Contrary to all assertions, the boars remained calm. This was probably because we housed male and female pigs separately.  We were very happy with the fact that no boar tainted carcasses were identified. Altogether, the transition was smooth.  

Did you experience any difficulties?

At the beginning we struggled a bit with the feed. The demand for boar feed with respect to amino acid endowment was clearly different from sow feed. At the time it was common to apply two different feed rations. Nowadays, tests and studies have shown that an age-appropriate feed formula for sows and boars together is sufficient. This makes the feeding easier. 

How do you look back on the past years?

When the market asked for meat from entire male pigs, they paid well too. Meanwhile, the retail market does not seem to want more boar meat. Therefore, the German slaughter industry has narrowed the payment scheme to the detriment of farmers. 

For more information on Georg Freisfeld, see https://www.hof-freisfeld.de/ (german). 

Pig farmer Annechien ten Have – Mellema

“Eliminating castration from our farm was a relieve”


Annechien ten Have runs a pig farm and arable farm with a biogas installation. Together with her son she owns 600 sows and 5.000 fattening pigs, plus 250 hectares of arable land. The farm is situated in Beerta, Groningen, The Netherlands. They work with Topigs Norsvin pigs, and sell the meat under their own brand name: Hamletz®. 



How did you get started in pig farming?

I took over my parents’ farm. As a child I already enjoyed helping my father. I have been keeping boars for 25 years now. 


Why did you decide to switch to boars?

We had by-products from breeding which were difficult to sell. At that time you were not aloud to deliver boars to the meat processing company. Finally we did receive an exception from the slaughterhouse which allowed us to deliver entire male pigs to a separate distribution channel. 

A few years later a welfare program was introduced for the UK market. Which meant that we could start producing entire male pigs. My husband Menno grew up on a dairy farm. He disliked castrating piglets, and questioned the need for it on our farm. I was used to the castrating, seeing it from his point of view was an eye-opener. I think it is good to rethink your your farm practices once in a while. 


What went well and what was disappointing about the switch to boars?

Eliminating castration from our farm was a relieve. It turned out that the feed utilisation improved, the pigs had less infections and there was less (unpleasant) work. Nothing was disappointing, only aggressive behavior became more of a point of attention. The pigs are jumping at each other more when they are not castrated. They show this behaviour as piglets and they keep performing it when they grow older. Looking through a window in the shed you can see this behaviour clearly. This causes bit more of a hassle.


How often does jumping behavior occur among the boars?

Very regularly, this behaviour is just in their nature. There is nothing we do to change this behaviour. But you get used to it. And now that I am, I find it too quiet when they just lie around all day. 


Did you have to make changes to your farm buildings?

We did not change the buildings on our farm when we switched our practices to non-castration. I am not sure what the ideal accommodation for keeping boars is, but I do think that it is important that they can all eat at the same time.


Hamletz nominated for Dutch Agricultural Entrepreneur of the Year 2019

In 2019 Annechien ten Have and her family were awarded as the Dutch Agricultural Entrepreneur of 2019. Watch the video of the nomination of Hamletz (only available in Dutch).


Anne Lacoste is R&D manager at Cooperl Arc Atlantique

We are happy and proud to have enhanced human and animal welfare”

Anne Lacoste on COOPERL’s transition to entire male pigs
S.A. COOPERL is one of the largest pork producers in France and a cooperative of farmers, feed producers, slaughterhouses, processors and butcheries. In 2013 COOPERL transitioned to the production of entire male pigs.

Why did COOPERL transition to entire male pig production?
The transition was driven by our earlier commitment to animal welfare. We were inspired by the example of producers in Germany and the Netherlands, who have already shifted to meat production with entire males. The males were comparable to fattening pigs (weight and age) of traditional UK and Spanish entire male production. Several visits to those countries helped to collect additional information and make a plan for testing the feasibility of such a transition at COOPERL.

How did the transition to entire male pigs work?
First we started trials to test the feasibility. In the first trial, we asked volunteer farmers to stop surgical castration, but not change any of their other practices. In that phase, we applied the human nose method for detecting boar taint, based on Dutch protocols. After an evaluation of the first trial, a second phase of optimisation took place. This optimisation focused mainly on feeding, as entire male pigs have a different feeding behaviour compared to castrated pigs. The evaluation of the trial on feeding practices involved a review of all the savings and costs of the shift to entire male pigs for farmers, feed producers, slaughterhouses and processors at COOPERL.

What were the consequences of the transition to entire males for farmers, feed producers and slaughterhouses?
The evaluation broadly concluded that the farmer benefited greatly: they no longer have to surgically castrate the pigs and the costs of accompanying health checks / treatments drop accordingly. Furthermore, farmers who produce entire males have fewer dejections and therefore can more easily manage the environmental impact of their operations. The farmer also has lower feed costs and are more lean carcass content of pigs, which means higher revenue.

The feed producer was however negatively impacted, because of the better feed conversion of entire males and therefore reduced quantities of feed required. Finally, slaughterhouses incur the additional costs of boar taint detection.

The overall evaluation of all costs and benefits showed that the transition would generate a net benefit for COOPERL.

What are the most important focus points for farmers?
At the beginning, the feeding behaviour and the occurrence of sexual behaviour changed. At present, farmers are focussed on boar taint prevalence, and the average company level of boar taint has decreased significantly.

How did you realize the transition to entire boars on all farms?
The transition from trial to commercial production took place in 2013. This included the establishment of a penalty system for carcasses with detectable boar taint. To monitor the quality, the human nose test was carried out on each individual carcass at the slaughterhouse. Systematic feedback on the level of boar taint detected in each batch was provided to the farmers. COOPERL also provided reports to farmers each trimester, enabling farmers to compare their performance to their peers. These reports included boar taint level and risk factor issues. Each carcass with boar taint is classified for some risk factors (weight, age, fat content) in order to help the farmer to better manage those.

How can boar taint be prevented in the long run?
COOPERL invested in research in genetics through its parent company NUCLEUS. Specifically, research was conducted by NUCLEUS jointly with the French Institute for Agronomical Research (INRA) to develop a method for qualifying boars in terms of the inheritable risks of boar taint, working with the Pietrain breed. This has led to individual testing of all Pietrain boars provided by NUCLEUS, and to the elimination of those detected as presenting a high risk of boar taint. As a result, NUCLEUS has developed a label “INO” (which stands for the French inodore, “without smell”) for these Pietrain boars.

How do retailers react to boar meat?
COOPERL’s transition to the production of entire males was not driven by demand of retailers & other buyers, nor by animal welfare organisations. To reassure retailers and Business-to-Business (B2B) buyers that the transition was beneficial for them and does not present risks, COOPERL ran trials with both. For example, COOPERL ran trials with store managers in which they were informed in advance that, for a given period, they would only receive meat from entire male pigs. There was a close interaction between a COOPERL representative and the store manager during that trial, to monitor any variations in sales and any consumer complaints.
COOPERL also organised numerous visits for retail and B2B representatives to come and see the full production process, especially the human nose method, to convince them of its reliability for detecting boar tainted carcasses. The human nose method at COOPERL is audited and certified annually by the German company SGS, which provides additional reassurance to the other segments of the supply chain.

Are there any remaining challenges?
COOPERL highlighted for its B2B clients that carcasses of entire males are easier to process than those of castrated males, which results in economic benefit. These efforts have proved successful in most cases, and COOPERL has managed to take retailers and B2B clients on board so that it successfully provides entire male meat to an estimated 13 million consumers per day. However, obstacles remain by clients that sell premium, labelled products as Label Rouge or organic pork which refuse entire males.

How does COOPRL look back on the transition to entire boars?
We are happy and proud to have enhanced human and animal welfare and reduce the environmental impact and increase farmer revenue, while maintaining a high quality of the final product to the consumers. COOPERL farmers – which are also Cooperative members- are also proud to have the lead in France with welfare issues. That step has allowed the Cooperative to rear antibiotic free pigs. No castration means no pain, no injury and less need for antibiotics.

Pig farmer Jaap Kreuger

“It is important that the pigs have good mobility”

Jaap Kreuger is 64 years old and lives in Woerden, west of the Dutch city of Utrecht. Together with his son he owns a 500 sow operation and 1,100 fattening pigs. Genetics is a rotation (Norwegian Landrace, Great York and Dutch Landrace) with a Tempo terminal.

How did you get into pig farming?
I’ve worked with pigs all my life. My father was a pig farmer and I worked on several pig farms myself. In 1993 I established my own farm in Woerden. In the future my son will take over the farm. For me pig farming is still a lot of fun and I’m actually quite proud of it.

When did you start keeping boars?
We have switched over to boars in 2010, simultaneously with the switch to the so called Better Life Label 1 star. This is a quality mark for improving animal welfare in pig farming.

What was the reason to switch?
In the past, you could only supply boars if they were delivered at a lower weight, which is economically unattractive. And then you also had the problem that the gilts were heavier than the light boars. So that did not work. Then in 2010, at a certain point, there was a good arrangement within the Star Program of Vion food, and it was fairly easy for us to switch.

What are the advantages and disadvantages of keeping boars?
What I find a great advantage is that it is less work. And castration is not fun either. There will be an effect on the feed conversion rate and the meat percentage. But I cannot say precisely how much, because I do not have a comparison. After all, other things vary as well. What is a side note is that more meat also means less bacon, and that is becoming a disadvantage.

How often does aggressive behavior occur among the boars?
Aggressive behavior is not too bad. We do have to deal with mounting behavior. Every once in a while you have a pig that keeps going. If there is a pig in the group with a bad leg, then there is a risk that it gets scratched.

How can you counter these behaviors?
It is important that the pigs have good mobility and that we have uniform groups. Then the risk of mounting is much less. And if one of the pigs is really excessive, you take it out and put it aside.

What has changed in the stables for keeping boars?
Nothing has changed at our farm, except that we have gone from 0.8 to 1.0 square meters. According to us, that only offers benefits: more space and health. And do not forget that the animals are still getting heavier, from 90 kg to 95 kg.

What do you think is the ideal accommodation for keeping boars?
I think the group size should not be too big. Then the risks are smaller, especially if you also have uniform groups. We work with wet feed, but cannot compare whether it would be better with a different feeding system.

How do you look back on your decision to keep boars?
As said before, it was easy for us to switch. We cannot accurately indicate the benefits of better feed utilization. The meat percentage has also increased. But I think that we have arrived at the lower limit for the fat thickness. This may need to be adjusted here. In addition, it is important that the abattoir accurately performs the detection for boar taint.

Pig farmer Wiebe in ’t Hout

“The technical results are better than with castrated animals”

Wiebe in ’t Hout is 36 years old and lives in Veendam. He is married and has two children. Together with his sister, Wiebe has an arable farm, broilers and, in addition, fattening pigs at 2 locations. At one location he has 7,000 fattening pigs with the Better Life Label one star certificate. At the other location, he has 5,800 fattening pigs in a conventional system.

How did you get into pig farming?
I’ve been into pig farming all my life. My father Hein was a pig farmer and I was ‘born and bred’ in pig farming.

When did you start keeping boars?
We switched to boars a long time ago. In 1998 we supplied boars for the Welfare program from Tesco. In 2010 we made the switch to Better Life Label 1 star. This is a quality mark for improving animal welfare in pig farming.

What was the reason to switch?
For me, there were two reasons: a demand from the market, and in addition, boars have better technical results with lower feed conversion and better growth.

What are the advantages and disadvantages of keeping boars?
What I find a great advantage is that the results are better. What disappointed me was the unrest. I had to get used to that.

How often does aggressive behavior occur among the boars?
That is different between groups. I think that it also varies with the season. When the first animals are delivered from the group, the ranking order is determined again. Then it can go wrong. Sometimes you have to remove an animal from the group and keep it separate.

How can you counter these behaviors?
You have to feed very differently. The content of protein and lysine must be increased. Furthermore, I also see differences in genetics. For example, the Duroc is significantly more quiet. Preferably I would keep boars and gilts together. But in the Better Life Quality Mark this is practically not feasible.

What has changed in the stables for keeping boars?
Nothing has changed at our company. The fact that we have gone from 0.8 to 1.0 square meters has, according to me, little effect on mounting behavior. For me, raising boars has a lot to do with genetics. Furthermore, it is not easy to predict, depending on the season.

What do you think is the ideal accommodation for keeping boars?
I think the group size should not be too big. Then the risks are smaller, especially if you also have uniform couples. The smaller the groups, the better. Furthermore, I have a long trough where the animals can eat at the same time, and there is less competition for the food.

How do you look back on your decision to keep boars?
I look very realistic at it. It is motivated by the market. And the technical results are better than with castrated animals. Furthermore, I expect that genetic improvement will make it gradually easier to keep boars.

Director R&D at Vion Ronald Klont

“We have 40 trained employees that perform the Human Nose Score test at the slaughter lines in the Netherlands.”

Ronald Klont is 53 years old and director Research and Development at the Vion Food Group since 2008. Vion Food Group is an internationally operating Dutch company with slaughterhouses and meat processing companies for pork and beef.

How did you get into the meat business?
I graduated at Wageningen University in animal sciences. My PhD thesis about the influence of pre slaughter stress on pork quality was defended at the University of Utrecht. During my PhD study, I did part of my research at INRA in Clermont-Ferrand, France. Throughout my whole career during 25 years, I have always been active in research into meat quality, working for research institutes, genetic breeding companies as well as for meat processing companies. Identifying directions for solutions against boar taint did always receive my special interest. At the Pig Improvement Company PIC I was involved in developing genetic solutions using DNA markers to select against boar taint.

When did the production of boars start?
Starting 2008, Dutch retail organisations did clearly focus more and more on animal welfare issues. Ending castration was one of the animal welfare issues that was focussed on. Producing boars became an integral part of the so-called Better Life Label that was introduced for pork meat in Dutch supermarket stores. Within this label Vion slaughters more than a million pigs annually.

How is boar taint prevented at Vion?
For reasons of quality assurance, Vion applies the so-called Human Nose Scoring (HNS) method at their three slaughter plan locations in the Netherlands. HNS functions as a safety net to prevent consumers being confronted with boar tainted meat. Currently, we have 40 trained employees that perform the Human Nose Score test at the slaughter lines in the Netherlands. To become a member of our HNS program, the employee has to be sensitive to both Androstonone and Skatole. The next step is that we do train them on giving scores to carcasses, ranging from 0 to 4, whereby 0 is no boar taint, 1 is slightly deviant smell, 2 is deviant smell, 3 is slightly boar tainted, and 4 is definitely boar tainted. We do exclude carcasses graded 3 and 4 from the fresh meat market. The score is allocated to the carcass at the slaughter line.

How do they check for boar taint?
We do heat the neck fat of the carcass and the employee smells assigns a score per individual carcass. A tester may smell for half an hour, then he has a half-hour break from smelling. At the moment our average boar taint prevalence is 3%. We do continuously monitor the accuracy of the individual assessor. By providing them feedback on their scoring results, we can immediately observe if the assessor starts to deviate in his scoring figures.

Can Vion guarantee zero boar taint to market and retailers?
Our key clients – including retail organisations – have from the beginning received information about our detection protocol. That is necessary for building trust in the market. We cannot guarantee a zero risk situation. But no company can guarantee this, as long as also carcasses from gilts can contain Skatole. My own experience is that producing and marketing boars is a about more than boar taint. Especially the leanness of boar carcasses is an important issue. Boar carcasses have more unsaturated fat. That may cause problems for some products on specific markets. For example for dry cured ham, we do need fatter animals. We do induce farmers to produce fatter animals by changing the payment scheme. Therefore we introduced a price reduction for animals with less than 10mm fat.

Director at Westfort Vleesproducten Jaap de Wit jr.

“The shift to entire male pigs did bring the farmers substantial economic gains due to the lower feed costs.”

Jaap is 41 years old and active at Dutch meat company Westfort Vleesproducten since 2013. His responsibility is the pork supply chain. A year and a half ago his father Jaap de Wit senior retired and  Jaap de Wit junior took over.

Can you tell us more about Westfort?
Westfort grew  out of two family businesses with a long tradition in the pork industry: Egbert Kruiswijk vleesproducten B.V. and Lunenburg vlees B.V. Westfort exports to over 25 countries, employing 1,000 people at three different locations in the Netherlands.

What has Westfort learned about dealing with boars?
At Westfort we have a long history in marketing entire male pigs. Currently, we slaughter 750.000 boars per year. Before 2007 we received about 1% of boars, just like all other slaughterhouses. The only market concepts accepting meat from boars were welfare contracts for the UK bacon production. This involved boars with a relatively low slaughter weight. In 2006 we started an experiment in which we evaluated the use of heating the boar carcasses and to test whether it was possible to smell boar taint. We use a burner instead of hot air. To our own surprise the number of tainted carcasses was much lower than expected. 2% to 3% instead of the 30% we were always told of.

Can you train people to recognize boar taint?
It took a year to fully develop the smell test into a Human Nose Method at the slaughter line. Our experience is that the selection and training of the people conducting the test is crucial. People have to learn to recognize the boar taint, and people also do differ in how accurate they are in detecting boar taint. That same year we did also conduct a large consumer evaluation experiment in cooperation with Wageningen University, with favorable results for the meat from entire male pigs that did pass the smell test.

We also experimented with the slaughter weight. We observed that for healthy animals with normal to high daily gains, broadening the weight range was not a problem. This made the way free for producing boars for the Dutch market. And we started to discuss the opportunities of producing and marketing entire male pigs with our suppliers, the pig farmers.

Is there a way to producing boars?
Based on our own experiments and on the consumer study, Dutch retail organization Coop was the first one who decided to sell meat from entire male pigs in their stores. A few years later market leader  Albert Heijn also switched to boars, and after this announcement the whole Dutch retail market quickly responded in the same direction. The consumer reactions were carefully monitored. We did a test together with Albert Heijn. Albert Heijn has sold boar meat for a certain period, but they didn’t communicate this. This led to very few complaints. Conversely, to say that it could be boars without it being meat from boars, gave more complaints. Without having further scientifically analyzed this, it seems to indicate that perception also plays a role and / or that a deviating smell can have more causes.

What changed for pig farmers?
The shift to entire male pigs did bring the farmers also substantial economic gains due to the lower feed costs. This resulted into a problem that was not foreseen. Other farmers were attracted by this economic benefit. Many of them stopped castrating the piglets, and the supply increased faster than the demand. This inbalance between supply and demand resulted in problems. The meat quality of boars differs from the meat quality of barrows. The meat company has to be motivated to slaughter and market boars, and they have to apply the Humane Nose method in an appropriate manner. Otherwise the market will be confronted with lower quality meat.

How does Westford deal with animal welfare organizations?
An important benefit for our company is also that Animal Welfare organizations do appreciate our efforts on this issue, thus contributing to our Corporate Social Reputation. At our company we are motivated to market meat from entire male pigs. But, it is important for those who consider to switch to realize that boars differ from barrows, with different market opportunities, and challenges as well. For some products boars are easier, and for other barrows are easier. In all cases an appropriate detection method is necessary.