Comparing overall welfare across species and conditions

An intellectual challenge

This post introduces an intellectual challenge. It formulates a problem, without giving any anwers. It is the kind of problem I like to wrestle with.

Welfare thermometer

While many aspects of animal welfare can be measured, it is still not possible to measure welfare overall. There is no welfare thermometer. Or, perhaps this is false. We do have a welfare thermometer. In fact, there are many. Everybody has his/her own animal-welfare thermometer, as (just about) everybody has an opinion about animal welfare.

Expert opinion & modelling

I have previously consulted welfare experts to express overall animal-welfare on a scale from 0 tot 10. I first did so for my PhD research when I consulted experts to validate welfare scores which I had derived through semantic modelling of the scientific literature about pregnant-sow welfare in different housing systems. Until now semantic models have been made to calculate overall welfare scores for pigs (sows), laying hens, dairy cattle and farmed fish (salmon). Using these scores it is possible to determine the level of welfare improvement, e.g. when alternative housing and managment systems are adopted. This makes it possible to assess the magnitude of welfare improvement, e.g. when sows are kept in groups rather than in individual housing.

Scores across species

All models concerned farmed species and all used scales from 0 tot 10. However, it does not automatically follow that the scores must have the same welfare meaning across species. The scales are likely to differ. A welfare improvement of 2 points on the scale for pig welfare probably does not represent the same welfare improvement in terms of intensity, duration and/or incidence as a welfare improvement of 2 points for farmed fish. Such a comparison requires deciding how the scales relate to each other. Else, it would never be possible to set rational or science-based priorities.

Other conditions

Furthermore, welfare concern not only addresses the way animals are reared on-farm. It may also concern entirely different conditions such as transport and slaughter conditions. Pigs may be stunned electrically or using CO2. Fish may be gutted, immersed in ice water or stunned electrically. Different levels of animal welfare are associated with these different methods of killing animals. And each of these treatments has a welfare value, an expression of what it would be like for the animals from their point of view. Such welfare value can be expressed using the (more or less standard) scale from 0 tot 10. But if so, how should we compare welfare scores between conditions, e.g. between farming and killing? Such a comparison would be necessary if we want to know, for example, if there is more welfare benefit from rearing poultry in welfare concepts (like Freedom Farmed/Better Life) than from implementing gas stunning instead of electrical stunning. This may not be an easy task, as these conditions (farming vs stunning) vary widely in all dimensions of welfare (intensity, duration and incidence).

Ultimate challenge

Suppose we could find ways to compare welfare across species and between diverging conditions within species. Would it then, in the end, even be possible to do both at the same time, i.e. to assess the degree of welfare improvement across conditions and species??? For example, would it ever be possible to compare the welfare benefits of say cage-free laying hens and proper stunning of farmed fish?

Post script

As I said, I won’t be trying to provide answers to these questions. However, if you would really want to and manage to focus on conditions with which you are fairly familiar, then, I think, most people probably can come up with some kind of reasoned opinion as to how such diverse conditions relate to each other in terms of animal welfare, and why. Perhaps you should just give it a try.

Figure from a brochure on semantic modelling.

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Comparing the welfare needs of poultry, pigs, fish and humans

Comparing welfare across species

Would it be possible to compare animal welfare across species? I wrote a paper on this subject some time ago (Bracke, 2006). In that paper I made a tentative welfare comparison between conventional farming systems for cattle, pigs, laying hens and broilers. This suggested it may be possible to make transspecies comparisons of animal welfare. It remained unclear, however, whether welfare could be compared across an even wider range of species. For this purpose I constructed a tentative table including fish and people. The table below lists the welfare needs of laying hens, pigs, Atlantic salmon and humans in a single hierarchy. It takes the welfare needs as described in Bracke et al. (1999c) as a starting point. This table suggests that it is possible to organise the welfare aspects of divergent species into a single hierarchy. This is not only true for farmed species like pigs, poultry and fish. Most notably, it also seems to be suitable to specify human welfare as well.


Bracke, M.B.M., 2006. Providing cross-species comparisons of animal welfare with a scientific basis. Netherlands Journal of Agricultural Science, 54, 61-75.

Bracke, M.B.M, Spruijt, B.M. and Metz, J.H.M. 1999. Overall welfare reviewed. Part 3: Welfare assessment based on needs and supported by expert opinion. Netherlands Journal of Agricultural Science 47: 307-322.

De Mol., R.M., W.G.P. Schouten, E. Evers, H. Drost, H.W.J. Houwers, A.C. Smits, 2006. A computer model for welfare assessment of poultry production systems for laying hens. NJAS 54: 157-168. (FOWEL model for layers)

Stien, L.H., Marc B.M. Bracke, Ole Folkedal, Jonatan Nilsson, Frode Oppedal, Thomas Torgersen, Silje Kittelsen, Paul Midtlyng, Marco A. Vindas, Øyvind Øverli, Tore S. Kristiansen, 2013. Salmon Welfare Index Model (SWIM-1.0): A semantic model for overall welfare assessment of caged Atlantic salmon – review of selected welfare indicators and model presentation. Reviews in Aquaculture 5: 33-57.

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Horror slaughterhouse to be memorial centre of compassion?

Indignation about animal cruelty

Widespread indignation about animal cruelty in a large slaughterhouse in the Belgium town of Tielt is calling for direct action based on arousal and compassion. Undercover footage taken by an animal-rights organisation, called Animal Rights, shows a most horrible treatment of pigs brought in for slaughter. Pigs are beaten, pulled by their ears, improperly stunned with electric shocks and drowning slowly in an extremely hot water bath. Perhaps a statue and world memorial site on animal suffering is called for.


In another (Dutch) blog on this topic I identified some related problems. I also made several suggestions on how we could deal with it. I suggested the Dutch livestock sector should take steps to reduce its involvement (as Dutch pigs were slaughtered illegally in the Belgian slaughterhouse). Simlary, concerned consumers may decide to go vegan (for a while), or make a donation. But animal-rights activists are also calling for the permanent closure of the slaughterhouse. In fact, the slaughterhouse has already been closed down temporarily by the Belgium minister of animal welfare. The property is now being protected against angry activists. There is a lot of indignation indeed, also among pig farmers. Perhaps so much so, that a more proper outlet of indignation is called for, over and above the exclamations in the (social) media.


In fact, so much animal cruelty footage has been accumulating on the internet over the years that it is time to recognize we need to acknowledge there is something fundamentally wrong with the way the Western world has been generating wealth and ‘wellness’.

Personification of suffering

On a daily basis we are sacrificing millions of animals for food, destroying natural habitats and we are causing almost endless amounts of suffering in our eternal pursuit of human health and happiness. The hidden suffering, for example, involved in the suffocation of fish caught at sea. The massive eradication programs of farm animals to fend off avian influenza. Mutilation practices on farms. Taken together the suffering involved in these every day practices is much worse than the suffering shown in the pig tapes.

In this respect, the horror house in Tielt is nothing but the personification of almost permanent animal suffering for the sake of economic gain. It is time we formally acknowledge its existence, ending our permanent denial and fabrication of alternative facts.


Here I propose to erect a statue for the pig that drowned. Perhaps even located on a world  memorial site for animal cruelty. Something equivalent to a Holocaust museum, or a statue to remember the soldiers who died in the war. The site of the horror slaughterhouse in Tielt, Belgium, if it closes down, may be a suitable location. It could be a place where people can visit, and share compassion for animals. A place where visitors are informed about the atrocities committed in the name of human happiness. It should be a place to remember what we have actually done, to learn how difficult it was to resist, and what was done to ensure it will never happen again.

Experience what it was like

The memorial could also be a house of horror. A place where you can experience what it was like to be an undercover activist with a hidden camera. And where you may get an impression of what it was like for the animals. For example, you may feel electric  shocks, be pulled on your ears, take a ride through the CO2 gas chamber, or be immersed in a very hot water bath.


The slaughterhouse-memorial could also be a place, perhaps, where visitors can express their indignation and anger about animal cruelty. Where they can be angry at the (image of the) perpetrators of animal cruelty. Angry at those who continue to deny the problem. Angry at governments for failing to take appropriate action. And perhaps angry also at yourself for having been indifferent for so long. Perhaps you can throw rotten tomatoes at an image of the slaughterhouse personnel, the director, the Minister of Agriculture, and/or even at yourself.

Centre of Compassion

First and foremost, however, it should be a Centre of Compassion, a Counter-Cruelty Centre. Where you can watch undercover video’s of animal suffering from across the world. Where you can learn how to respond appropriately. How to abstain from animal cruelty yourself and instead appreciate a more positive relationship with animals.


Ideas expressed in this post build on a previous proposal to erect a statue for the laboratory mouse, and the virtual animal museum.

Horror slaughterhouse memorial

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Happiness: Fact or fiction – Good or bad?


Today is the UN’s International Day of Happiness.

Skandinavian countries, Switserland, Australia, Canada and the Netherlands are among the happiest countries in the world. Over the past year, the large majority (88%) of Dutch people were happy, i.e. they gave a welfare score of 7 or higher on a scale from 0 to 10. Only 3% were unhappy as indicated by a score of 4 or lower. These welfare scores have been stable since recording started in the Netherlands in 2013. Last year, 7500 adults self-reported happiness scores measured at different time points throughout the year.

In 2016 the Dutch economy finally started growing again, and the influx of refugees stopped. No terrorist attacks happened. We had reason to be happy. It was another nice and warm year, in part thanks to our fantastic greenhouse emissions.


Happiness or welfare is an intriguing concept. Most people firmly believe that it is a truly subjective notion: How happy you are feeling right now is exactly how happy you really are. Happiness is for everybody to decide for him/herself.

But is it really as subjectieve a notion is it is commonly believed to be? And are the affluent Dutch people really that happy? Are they really as happy as they say they are? Or are they perhaps fooling themselves?

A mater of scale

A main source of error or ambiguity arises from the fact that the answer depends on the actual scale that was adopted by the respondent. The researchers supplied a scale from 1, very unhappy, to 10, fully happy. This scale is relative to the respndent’s domain of application. If I use a scale that is relative to how happy I have felt myself or how happy I think familiar people in my network are, then I could be giving very different scores than when I compared myself to the rest of the world, for example. Also, when I happen to think of the things I struggle with the most in my life, I would give a much lower score than when I would ignore or ‘forget’ about these difficulties. People are not always equally aware of what their real problems are.

Moment of truth

Imagine the final moment of truth: The moment you are about to die. You may want to ask yourself: Have I been really happy? But you may also want to ask yourself a more important, related question involving not only your own happiness, but also the happiness of others: Have I been good? Have I done more good than bad?


It’s nice if you were happy. But it’s not so nice if your happiness were based on illusions. When you are mistakenly told you’ve won the lottery or the Golden Globe, you may have felt very happy, but that’s not the kind of happiness that is likely to matter at the moment of truth. You’d much rather feel happy about what you believe to be true and valuable. That’s why you probably don’t want to be a drug addict, or a tv or gaming junky, no matter how happy that would make you feel, and no matter how much the side effects have been mitigated. You probably want to be happy while having done more good than bad overall in your life time.


When we try to answer this question, the first thing to notice is that this is not a subjective question. You cannot make the answer true, simply because you (want to) believe that you have done more good than bad. It has to be true.

More good than bad?

When you ask them, most people honestly believe they have done more good than bad in their life time. For this to be true, however, you must have generated more happiness than suffering overall. Having felt happy yourself is a good start, but it is not enough. For your happiness is bound to have had implications for the happiness experienced by others, including both humans and animals. So if you have been living and consuming happily, you may fool yourself into focusing only on the pleasures of consumption.


In all honesty you must admit you are also co-responsible for the happiness and suffering associated with production, and with the disposal of your waste products. Starting from your diapers and bottle of milk all the way to your last holiday and chemotherapy: How much happiness do you think you will have been able to generate? And in doing so, did it really make you happy? I hope it did. But in order to be confident, we need to integrate the welfare scores into a sound moral assessment of all the welfare consequences of our actions. I hope we may then conclude with confidence that we are justified in having felt happy as we have also been doing more good than bad overall.

Happiness as dark shadow

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Oh my deer, I’m so hungry – A student project proposal

Proposal for a student project to quantify feeding motivation

This is a ‘recipe’ for a great student project aimed at quantifying feeding motivation of deer in a deer-park. Recipe by: Marc


In order to run this project you need the following:
1 or 2 motivated students
A teacher
A deer-park
Some bread
A plastic bag
A timer
A note book


Prep: 1 week
Cook (data-collection): 12-16 weeks (or so)
Finish (analyse & write report): 4-8 weeks

1. Objective: We want to quantify hunger in deer by showing differences in feeding motivation between moments of more and moments of lower anticipated hunger levels.

2. Preparation phase: You must find a contrast between moments expected to be associated with higher and lower feeding motivation, e.g. between days with more and fewer visitors, between days with better and worse weather conditions, or between morning and afternoon visits. You also need to find the most suitable primary and secondary parameters to record, e.g. day of the week, time of day, date, weather conditions, left-over food in the enclosure, latency to notice your arrival, speed of approach, number of animals gathering, distance over which you are being followed if you walk along the fence holding food.

3. Data collection: Record the above in a systematic way (using a protocol designed to avoid potential biases)

4. Analysis: Test whether deer were less motivated to feed on busy days, possibly depending on weather conditions and time of day.

5. Write the report: Finally, make one or more figure showing the results, and answer the question whether you succeeded in finding differences in feeding motivation in accordance with expectation, esp. that the more the deer have been fed, the less motivated they will be for being fed.


This setup can be used on other species as well, e.g. sheep, horses, cattle, pigs and ducks. Also, if the deer are normally fed with one type of food such as bread, it may be interesting to examine the effect of feeding something entirely different, e.g. the feeding of grass or twigs (but make sure you are not feeding toxic plants). It could also be used to test variables in learning, e.g. differences between different types of food or different cues predicting food. Another potentially interesting option is to use ambiguous cues as a measure of cognitive bias, and thus welfare.

Finally, if you like this idea, you could let me know, e.g. via a comment below this post.

Deer project

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Plea for Ag-gag in the Netherlands

Plea to draft Ag-gag legislation in the Netherlands

This post considers why we need ag-gag. Ag-gag laws protect the livestock industry from exposure of animal cruelty by animal activists. This mainly US-based legislature forbids the undercover filming or photography of on-farm activities without the consent of the owner. Many arguments support the drafting of ag-gag legislation in the Netherlands.

The Netherlands first

The Netherlands would not be the first country in the world to draft an ag-gag law. The US and Australia already have such legislation. But the Netherlands could be the first country in Europe. And it could be the first Dutch country to draft such legislation. If we can be first twice, that’s a bit like being second after all.


The Dutch parliamentary elections of March 15 2017 resulted in a rather right-wing victory. A centrum-right coalition is to be expected, as well as a Christian Democrat as the next minister of agriculture. The new government can make itself immortal, though some would prefer saying ‘immoral’, by proposing ag-gag legislation. The Netherlands is the second largest exporting country of agricultural produce in the world. We are second only after the United States, despite being such a tiny and densely-populated country in the NW of Europe. Our livestock industry is hugh. The new government should grab this unique opportunity to celebrate this unbelievable achievement of agricultural rationalization by drafting an ag-gag law, before it is too late.

Political parties

Below I will present the main reasons each political party may have for supporting ag-gag.


Prime minister Mark Rutte’s VVD won the elections. The acronym VVD stands for People’s Party for Freedom and Democracy. The VVD is a right-wing, liberal party. It is fond of entrepreneurs. Thus, the VVD will wholeheartedly support ag-gag to protect the livestock industry and the farmers’ freedom to do business without restrictions, and without the fear of trespassing or of hiring cheap labour with malicious intent (like this in NL this in FR, or this in BE).


Geert Wilders’ populist PVV is the second largest party. Wilders hates terrorists, but he seems to like pets. His party got us the animal cops. Farm animals, however, are not his main concern, and he seems to like the severest punishments for unwanted behaviours. So he will probably support ag-gag too.


The centrum-right CDA is the main farmers’ party. The CDA will certainly be part of the government again. In the past the CDA has always claimed the Ministry of Agriculture, and will undoubtedly do so again this time. Jaco Geurts is a well-known CDA politician and activist pig-farmer running for the Ministry’s vacancy. And even when he doesn’t get the job, he will be the most likely candidate to draft the ag-gag legislation.


D66 is the Party for education and Europe. It is another winner of the elections, and a likely participant in sharing gevernmental power.

It is a very pragmatic party, and probably the only party in the coalition concerned about the environment. In virtue of its pragmatism it may propose that farm buildings be painted green. Or it could argue that intensive farming is the most sustainable way to reduce global warming, and thus favor ag-gag. Especially when ag-gag would be the price to pay to make a deal with the Trump administration securing our ag export to the US. Ag-gag is symbolic anyway, because undercover operations are rare in the Netherlands.

D66 also used to be in favor of referenda, but since the unwanted outcome of the Ukrain referendum it has become more cautious. Otherwise it may have proposed to have an ag-gag referendum first. Or perhaps it will propose to amend the ag-gag law with an option to allow the release of sensitive material only if it is shown by referendum to be footage of acceptable animal cruelty.


GoenLinks is the biggest Green Party. It attracted many young voters and actually won the high-school elections. GroenLinks, however also welcomes immigrants, so it must deal with a devilish dilemma: To let the immigrants in or to let the farm animals out. Since people are more important than animals, GroenLinks will probably favor the immigrants, and there goes its initial opposition to ag-gag.


The Socialist Party has never really cared about animal welfare, so why would it oppose ag-gag now? Perhaps it is an honor to represent the worst-off, and concern for animals may pose a threat to protecting poor people.


The Labour Party is the big loser of the 2017 elections. It held the post of Secretary of State, i.e. former ministry, of agriculture over the last four years. The farmers disliked the PvdA minister so much that the party will probably abstain from casting votes when the ag-gag law is passed.


I will not discuss all of the remaining smaller political parties, because it doesn’t matter what they will vote for anyway. But the Party for the Animals is a notable exception. It deserves careful consideration. Will Marianne Thieme and her four other MPs vote against ag-gag? I don’t think so. The Party for the Animals is no longer a single issue party. People are animals too, you know. So the problem arises whom to protect: many poor farmers or a couple of creepy activists? The animals can’t be saved anyway, because of the firmly-established right-wing government. And besides, even if the PvdD, with or without the support of other parties, could block ag-gag it should not do so. For ag-gag will be a blessing for all parties that unsuccessfully try to oppose it. So we can expect a lot of fuss of parties secretly hoping the law will pass anyway.

Postscript – Disclaimer

From reading this post you may rightly or wrongly infer my (MB’s) personal opinion regarding Ag-gag. You will be solely responsible for any such inference (see also my Dutch post on freedom of expression, also for scientists).


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Do pigs play with chains? Science versus society


Scientists object to the suggestion that pigs may be playing with toys like metal chains in their pen. In ordinary language, however, it is perfectly fine to use the word play for such animal-material interaction. Apparently, the word ‘play’ has a more restricted meaning in science than in normal language. More words are used differently in science. In particular, words like stress and pain have been operationalised in science to allow scientific measurements without at the same time implying negative emotions or feelings. By contrast, play is often associated with positive emotions. This blog questions the scientific use of the word play and argues that pigs may play with chains much in the way humans can play with a pencil in their hands or can chew gum. However, when pigs are said to play with ‘enrichment’ materials like ‘toys’ it is not automatically implied that these materials are sufficiently enriching to induce positive emotions.


Many producers, suppliers and consumers tend to use the term ‘play’ to refer to object manipulation in pigs. Correspondingly, the word ‘toy’ is frequently used for point-source pig enrichment materials like chains, pipes and ropes in the popular press. I (MB) have used the word play, in particular referring to growing pigs interacting with a metal chain.
However, several applied ethologists have objected to this use of the word play, arguing that it is not in accordance with the conventional use of the term in science.
In applied ethology it is not generally accepted to say that pigs are playing with a chain. This is because play typically requires variability of behavioural elements and certain locomotor elements like being boisterous.
Play may roughly be divided in locomotor play and object play. This blog concerns the more static object play. Here, I will present a ‘dispute’ between science and society regarding the use of the term play to refer to object play like chain manipulation in pigs. I will try to clarify and specify the use of the word ‘play’ in science and ordinary language so as to inform interested readers, e.g.scientists pig farmers and the public, about the distinction, challenge the scientific convention a bit, and perhaps widen the scientific use of the word ‘play’. The central question then is: Is it proper to say that animals like pigs play with objects like metal chains? Do pigs ‘play’ with chains?

Neutral terms

To refer to object play scientists tend to prefer more neutral terms like ‘use’, ‘animal-material interaction’ (AMI), ‘oral/manipulative behaviour’ and ‘object-directed behaviour’.
This preference may derive both from a need to be able to measure/operationalise the term and from a reluctance to imply the presence of emotions. The latter has a long history in science in which behaviourism determined scientific thought. In this respect it is certainly more accurate, more neutral, more ‘objective’, more safe to say that a pig is engaging in AMI or showing object-directed behaviour, than to say that the pig is playing with the chain.
Linguistically, of course, it is more convenient and appropriate to use the word play than to ‘engage in object-directed behaviour’. However, in science accuracy takes precedence. But in the case of chain manipulation there hardly seems to be any ambiguity as regards descriptive accuracy, as it is very clear what is implied in terms of behaviour if it were referred to as chain play. Furthermore, when in science play typically requires variable behavioural elements, and if that is not what pigs do when they interact with chains, should we then avoid using the word ‘play’ (and perhaps even deny that pigs show much object play) or may we also question variability as a defining characteristic of play? The same goes to some extent for the requirement that play must be associated with positive emotions. I will come back to these points below.

Different meanings of words used in science and common language

For now it is sufficient to point out that the word ‘play’ seems to be used differently in science and in common language. Notable differences in word use between ordinary language and science are also found in the case of words like ‘pain’ and ‘stress’. These words are heavily loaded with a connotation of (negative) feelings, namely pain and stress respectively. However, this is not what scientists want or can imply when they record nociceptive responses or stress hormones. Since empirical science is focusing on observable phenomena and since emotions cannot be measured, scientists have previously preferred to avoid implying emotions altogether. Hence, the scientists’ preference for operational definitions may have resulted divergences from common language. The divergence, however, is not necessarily restricted to (a denial of) emotions as it also applies to words like ‘fit’ (as in ‘survival of the fittest’) and ‘flu’ (which in science, but not in every-day life, requires the presence of influenza virus). In these cases the divergence originates in the scientists’ need to use clearly defined operationalised concepts that allow uniform measurements. But in the case of object play, there doesn’t seem to be much of a need for an operational divergence between science and ordinary language, if we could agree to use the word to refer unambiguously to the object-directed behaviour that is being observed.

Feeding and drinking

In relation to this it also seems relevant to point out that science does not always seem to be consistent in applying its own principles either. For if it were absolutely necessary to stick to directly observable phenomena, then it would be unscientific to use terms like ‘feeding’ and ‘drinking’ in behavioural science. However, ethologists have no problem using these terms when they in fact only record ‘head-in-feeder behaviour’ or ‘head-towards-drinker behaviour’. As, while these behaviours will mostly indicate feeding or drinking activity, we cannot be absolutely sure. Perhaps, in fact, some feeding or drinking may actually be playing with food or water!

Technical definition

A related point here is that it is commonly accepted in science to use technical definitions. So, as it is allowed to use the term ‘feeding’ for ‘head-in-feeder behaviour’, so it should be allowed in science to state in the methods section of a paper that the authors will use the term ‘play’ to refer to ‘object-directed behaviour’. A more general adoption of such a convention would in the end sanction the use of the term ‘play’ to refer to object interaction/manipulation. Note: I’m not arguing that we should use the word play, but I’m pointing out that we could, if we so preferred, and as it so happens I do if only because it sounds better linguistically (and I don’t see major reasons not to).

Exploration as underlying motivation

Scientists tend to classify object play as a form of exploratory behaviour. But is this correct?
Exploration implies there is something to learn (goal-directed information gathering). But what would a pig learn from manipulating a metal chain? A rope is attractive to pigs because it can be destroyed. But what kind of exploration is involved in manipulating the same chain over and over again, or even in destroying a similar kind of rope over and over again? The object-directed behaviour that starts as exploration, may at some point stop being (primarily) motivated as such.
Related forms of pig enrichment raise similar concerns. For example, floor feeding or providing a handful of straw or maize silage. Is that exploration? Or is that just feeding behaviour? These materials are typically called enrichment materials, however, thereby slightly implying they result in exploration and a related motivational state, despite the fact that this is certainly questionable.
There is actually a very fine line between one form of object play and another. Take a chain. Pigs mostly interact with the end of the chain, i.e. the last links/shackles. Does it matter, if the shackles are attached to a chain, or loose, in order to call it exploration or play? Suppose the shackle is a small pebble, on which pigs, esp. outdoor sows, may root, bite and orally manipulate for prolonged periods of time. Is it exploration? Should we just call it ‘use’, or perhaps even classify it is ‘abnormal behaviour’? I don’t seem much harm in calling it ‘play’.
In fact, it may be questioned whether scientists really need to be able to establish the underlying motivation before they can label a behaviour properly. For example, mounting is commonly listed as a behavioural element, even though, especially in younger pigs, it is often not clear whether such behaviour is indeed sexually motivated. For walking it is even more evident that scientists do not require knowing what is the underlying motivation before the behaviour can be labelled as walking. Behavioural elements may simply have different underlying motivations. So it may not be a problem to label chain manipulation as play and at the same time allowing for the possibility that the animal may be exploring the chain to some extent at the very same time. In fact, it may also be acknowledged that it is not even certain that chain play is not at the same time stereotypic and perhaps indicative of stress and negative welfare. However, when frustration clearly has the upper hand, as seems to be the case in pigs trying but failing to grab and bite a hanging ball or wood, then I would personally prefer to avoid using the word ‘play’ as a label, even though the causal motivation initiating the behaviour may well be/have been a motivation to play.

Variability and locomotion

Classic, scientific definitions of play (e.g. Burghardt 2005) suggest that if the interaction with the chain has characteristics of play and is accompanied by other behaviours typically classified as play (e.g. running; twisting; flopping; play fighting) then perhaps yes it can be defined as play – but it might equally have a different underling causation (esp. exploration or foraging). Scientists would want to see that unpicked before deciding what behaviour class it falls into, even though they recognise that these functions may overlap to some extent.
It may be questioned, however, if it is necessary for object play in particular to be variable, developmental and involve locomotor elements like running, twisting and play fighting.

Human play

In ordinary life the term ‘play’ is notoriously difficult to define (Wittgenstein 1953) and often used for a variety of human behaviours. Some of these can be very much focussed (hence lacking variability) and involve very little locomotion. Playing a game of chess would be a typical example. By contrast, other types of play may involve a lot of locomotion, but still be extremely serious, even quite emotionally negative at times, and following fixed rules, like playing a game of soccer.
Some of these play behaviours are very difficult to distinguish from serious adult behaviour as indicated by the level of seriousness of being engaged in the activity. A child playing with Lego, for example, may be extremely serious about it (and not show much locomotor activity). An adult human playing a game of soccer may be extremely frustrated e.g. about being unable to perform properly or win. Nevertheless, it would be very strange if a scientist would come along telling people that such children playing with Lego and adults playing soccer are in fact not playing but ‘showing human-Lego/ball interaction behaviour’.
In this regard it may be relevant to note that most, if not all, of the leisure activities performed by young human children are considered play. In the case of growing and fattening pigs we may be tempted to believe that these animals are more or less adult because of their size. However, a finishing pig weighing 100 kg is, in fact, a very young animal, that has hardly reached its natural weaning age. So fattening pigs interacting with chains are very young animals too.
My most favourite comparisons are to compare chain play in pigs with human behaviour playing with a pencil or some other small object, and chewing gum. Adults may show these behaviours too. They may be repetitive, without being stereotypic (at least not in the sense of being indicative of substantially reduced welfare), and typically occur without any locomotor elements such as running, frolicking, gambolling or jumping about. Nevertheless, I my view such behaviours can properly be labelled as play, and similar behaviour in animals may be labelled similarly.

Voluntary or coerced, pleasure or frustration

Play is typically associated with positive welfare, with having fun and/or pleasurable emotions. Chain manipulation may be stereotyped, especially in tethered sows. This may or may not directly indicate negative affect (e.g. hunger or fixation stress). However, this does not imply that chain manipulation in younger pigs is similarly ‘abnormal’ or stereotyped. In fact, the manipulation of straw, the ‘ideal’ type of enrichment, may be at least as abnormal, as pigs would rarely be observed interacting with straw under natural conditions for long periods of time. Extensive straw manipulation under natural conditions would not be beneficial for pig survival. Furthermore, chain play in young pigs is rather voluntary as these pigs are typically fed ad libitum and kept in groups where the chain is hanging at a pen wall. Young pigs, therefore, can, it seems, easily ignore the chain if they would want to. Hence, it is likely that most of the interaction with the chain is motivated by the pigs wanting to interact with it, even though this, in my view, does not necessarily imply that their welfare is positive overall.


In this short communication I have tried to clarify the differences between the conventional use of the term ‘play’ in science and its use in ordinary language. I have argued that the classical scientific use, requiring behavioural variability, positive emotions and locomotor elements, may be too rigid and that there are good reasons to allow the word ‘play’ to be used for object-directed behaviour in the case of pigs playing with point-source objects like a metal chain, rope or plastic pipe. Pig farmers, suppliers and the public should be aware of the concerns scientists have in using the term play, as it may not always be associated with positive emotions and further research would be needed to establish more clearly if pig chain play classifies as play in the classical sense currently used in applied ethology.


Burghardt, G.M., 2005. The genesis of animal play: Testing the limits. MIT Press.
Wittgenstein, Ludwig (2001) [1953]. Philosophical Investigations. Blackwell Publishing.

Pig tail

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Redirected behaviour – What is it and why is it important?

What is redirected behaviour, and why is it important? When the normal route is blocked, behaviour may be redirected towards another goal. Such redirected behaviour can both be a welfare sign and a welfare solution.

Redirected behaviour

The normal path of behaviour may sometimes be redirected towards something else. For example, when a curious animal like a ? is motivated to investigate the surroundings and root in soil, it may redirect its behaviour towards other ??? in a barren pen. Such redirected investigative behaviour may thus lead to tail biting. Similarly, when you are having trouble at work, you may be inclined to retaliate. However, when this is not possible, you may be redirect your aggression. For example, you may be ? at ?, or you may temporarily be a more avid sportsman.


Animals are not always free to do as they please. When a normal route is blocked, some behaviours may be redirected towards another goal. Redirected behaviour is generally indicative of reduced welfare, i.e. negative experiences. However, it may also provide a solution so as to prevent more serious adverse consequences. In this way, redirected behaviour may both be a sign and a solution of an underlying welfare problem.

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Branched chains as enrichment for pigs (technical description, pictures and video)

This post illustrates the so-called branched chain design. This is an improved type of chain that seems most suited as a starting point towards providing proper enrichment (as required by e.g. EU legislation) for conventional, intensively-farmed pigs. However, also pigs on straw may benefit from such chains. Below the description of the branched chain design you can find some pictures and video clips of branched, anchor-type chains for pigs (conventionally-housed weaners and growing fattening pigs, and gilts kept on straw).

Specification of the branched chain design

1: Object-design: A branched chain consists of a vertically-positioned long chain with its end resting on the solid floor over a distance of 20 cm. Two or three additional chain ends (branches) end at or slightly below the nose height of the smallest and middle-sized pigs reared in the pen.
2: Material: The chains are stainless-steel anchor chains (for at least the last 5-10 links of each chain end). Recommended dimensions are 7mm for growing-fattening pigs, 5-6 mm for weaners, 4-5 mm for piglets and 8 mm for sows.
Anchor chains have links which are more round and heavier than the cheaper, more oval-shaped c-chains. Note that the indicated sizes refer to the diameter of the metal, not the diameter of the links. For example, a 7 mm anchor chain for finishers has links measuring 36×23 mm. Preferably various chain sizes should be provided in the pen, esp. when the pen may contain pigs of variable sizes (e.g. from 25 to >100 kg). Stainless-steel anchor chains are more expensive, but only the last 5 or so links need to be replaced when worn e.g. every 5 – 10 years.
3: Availability and placement: One branched chain is provided for every 5 pigs.The chains are spaced apart as much as possible, preferably with at least one pig length between 2 branched chains in a pig pen. The branched chains are attached at the top end of the pen wall, over the solid floor, and not in the dunging area.

The description of the branched chain design was derived from: Bracke MBM, 2017. Chains as proper enrichment for pigs (incl. supplement). In: Spinka M, editor. Advances in Pig Welfare: Elsevier.

Table. Chain link dimensions

Chain link thickness (mm) Length (mm) Width (mm)
4 26.5 16
5 ~28 ~17.5 (estimate)
6 30 19
7 36 23
8 40 26
9 ~44 ~30 (estimate)
10 48 34

Pictures of branched anchor-type chains

Short chain and ball. Note the bite marks on the ball. The ball is hanging on a c-chain (oval shaped). The short chain resembles an anchor chain but isn’t (links not massive enough). Short chain, ball and branched chain made of suboptimal c-chain links. This type of branched chain uses only 1 fixation point (reducing costs). Branched anchor-type chain with 3 branches. Only top left branch is made of c-chain in order to ‘test’ pig preferences for the anchor-type chains (top right branch).
Four stainless-steel anchor chains. Two middle chains are worn by long-term use (5-10 years). Outer chains show original shape. Branched chain provided to weaned piglets Occasionally a pig will be reaching up. But normally they show downward-directed behaviour.
Branched chain for fatteners Most manipulation of the branched chains is floor directed. Both rooting and biting/chewing/playing.
Floor directed ‘rooting’. The pig’s nose really ‘fits’ a floor-directed orientation.
Also some more horizontal chewing Sometimes more pigs are interested in the same thing.
Side-way chewing (fits into cheek fold for canine teeth). Taking a whole branch (10 links) into the mouth. Three pigs all at once.
Some occasional pulling. Empty straw-bricket container. The floor plate may be used to keep a chain from getting stuck in the slats and/or repair when the floor below the branched chain gets worn. Gilt in a straw pen next to a branched chain between the lying area (front) and dunging area in the back of the pen.
Floor-directed chain manipulation may be labelled ‘rooting’ … ..not just because there is also some straw…  … it resembles stone chewing seen in outdoor sows.
A second branched chain in the same pen containing four gilts. Grabbing the chain horizontally, showing the cheek fold. A branched chain in another pen containing two gilts on straw.
Floor directed behaviour Biting the chain occasionally. Fixation of the floor chain using the right front leg. True ‘manipulation’ (as manus in Latin means ‘hand’).
Branched chain worn temporarily as an ‘ear ornament’. Two gilts playing with the branched chain at the same time. Anchor-chain links worn (right) by pig manipulation.





These pictures may be used for non-commercial purposes & publications provided copy-rights (MB) are acknowledged.

The video clips below show the pigs in action.

This video shows that a hockey-type ball may be frustrating for pigs, and that the branched chain design is much more appreciated, even by organic pigs.

Related posts:

Chains as enrichment for pigs (Book chapter with supplement)
Ketting als hokverrijking voor varkens (incl. link naar het supplement)
Pig animation – Improved, branched chain design as proper enrichment for pigs
Branched chains as enrichment for pigs (technical description, pictures and video)
Proper enrichment for intensively-farmed pigs – From review to preview
A collection of pictures of other enrichment materials for pigs can be found here: Prize contest (Prijsvraag) 2011.
Do pigs play with chains? Science versus society


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