Towards a common conceptual framework and illustrative model for feather pecking in poultry and tail biting in pigs – 8. References

This is post 8. “References” of:

Towards a common conceptual framework and illustrative model for feather pecking in poultry and tail biting in pigs – Connecting science to solutions

Marc B.M. Brackea, T. Bas Rodenburgb, Herman M. Vermeera, Thea G.C.M. van Niekerka
a Wageningen Livestock Research
b Wageningen University, Dept. of behavioural ecology

Reading guide

This is one of 8 blog posts under the heading of: “Towards a common conceptual framework and illustrative model for feather pecking in poultry and tail biting in pigs – Connecting science to solutions”. It contains the following sections/posts:

  1. Introduction, specifying the need to compare feather pecking (fp) in layers and tail biting (tb) in pigs
  2. Terminology, specifying the various concepts involved in fp/tb.
  3. Overview of main similarities and differences between feather pecking and tail biting
  4. Farmer as a risk factor, emphasising, perhaps for the first time, that the farmer is a kind of ‘animal’ that is part of the problem (and the solution).
  5. Models, reviewing available conceptual models of fp and tb, as well as presenting a new ‘face model’.
  6. Disease framework, arguing that fp/tb may be regarded as a medical disorder, over and above being an abnormal behaviour per se.
  7. Evolution and domestication, emphasising the need to view fp/tb as a phenomenon an evolutionary and genetic background.
  8. References

The entire text (8 posts) can be downloaded as one pdf here.

8. References

Ali, A., Cheng, K.M., 1985. Early egg production in genetically blind (rc/rc) chickens in comparison with sighted (Rc+/rc) controls. Poultry science 64, 789-794.

Anonymous, 2001. Scientists’ Assessment of the Impact of Housing and Management on Animal Welfare. Journal of Applied Animal Welfare Science 4, 3-52.

Beilharz, R., Luxford, B., Wilkinson, J., 1993. Quantitative genetics and evolution: is our understanding of genetics sufficient to explain evolution? Journal of Animal Breeding and Genetics 110, 161-170.

Bijma, P., Muir, W.M., Ellen, E.D., Wolf, J.B., Van Arendonk, J.A., 2007b. Multilevel selection 2: estimating the genetic parameters determining inheritance and response to selection. Genetics 175, 289-299.

Bijma, P., Muir, W.M., Van Arendonk, J.A., 2007a. Multilevel selection 1: quantitative genetics of inheritance and response to selection. Genetics 175, 277-288.

Blokhuis, H., 1986. Feather-pecking in poultry: its relation with ground-pecking. Applied Animal Behaviour Science 16, 63-67.

Bokkers, E.A., Koene, P., 2004. Motivation and ability to walk for a food reward in fast-and slow-growing broilers to 12 weeks of age. Behavioural Processes 67, 121-130.

Boumans, I.J., 2017. Simulating pigs – Understanding their motivation, behaviour, welfare and productivity, Wageningen University, Wageningen.

Boumans, I.J., Hofstede, G.J., Bolhuis, J.E., de Boer, I.J., Bokkers, E.A., 2016. Agent-based modelling in applied ethology: An exploratory case study of behavioural dynamics in tail biting in pigs. Applied Animal Behaviour Science.

Bracke, M.B.M., 2008. Richpig: a semantic model to assess enrichment materials for pigs. Animal Welfare 17, 289-7286.

Bracke, M.B.M., 2017. Chains as proper enrichment for intensively-farmed pigs?, in: Spinka, M. (Ed.), Advances in Pig Welfare, Elsevier, pp. 167-197.

Bracke, M.B.M., Hulsegge, B., Keeling, L., Blokhuis, H.J., 2004a. Decision support system with semantic model to assess the risk of tail biting in pigs: 1. Modelling. Applied Animal Behaviour Science 87, 31-44.

Bracke, M.B.M., Vermeer, H., Bokma, M., Van der Peet, C., Bolhuis, L., Leeijen, J., 2012. Checklist aanpak staartbijten bij (biologische) varkens. [Checklist dealing with tail biting in (organic) pigs] Flyer. Available: Accessed 11-5-2016, Wageningen Livestock Research, Lelystad.

Brunberg, E.I., Rodenburg, T.B., Rydhmer, L., Kjaer, J.B., Jensen, P., Keeling, L.J., 2016. Omnivores going astray: a review and new synthesis of abnormal behavior in pigs and laying hens. Frontiers in veterinary science 3.

Camerlink, I., Ursinus, W.W., Bijma, P., Kemp, B., Bolhuis, J.E., 2015. Indirect genetic effects for growth rate in domestic pigs alter aggressive and manipulative biting behaviour. Behavior genetics 45, 117-126.

D’Eath, R.B., Arnott, G., Turner, S.P., Jensen, T., Lahrmann, H.P., Busch, M.E., Niemi, J.K., Lawrence, A.B., Sandøe, P., 2014. Injurious tail biting in pigs: how can it be controlled in existing systems without tail docking?  8, 1479-1497.

Daigle, C.L., Rodenburg, T.B., Bolhuis, J.E., Swanson, J.C., Siegford, J.M., 2015. Individual consistency of feather pecking behavior in laying hens: once a feather pecker always a feather pecker? Frontiers in veterinary science 2, 6.

De Waal, F., 2016. Are we smart enough to know how smart animals are? WW Norton & Company.

De Waal, F., Johanowicz, D.L., 1993. Modification of reconciliation behavior through social experience: an experiment with two macaque species. Child development 64, 897-908.

Di Giminiani, P., Edwards, S.A., Malcolm, E.M., Leach, M.C., Herskin, M.S., Sandercock, D.A., 2017. Characterization of short-and long-term mechanical sensitisation following surgical tail amputation in pigs. Scientific Reports 7.

EFSA, 2007b. The risks associated with tail biting in pigs and possible means to reduce the need for tail docking considering the different housing and husbandry systems. Available: Accessed 10-5-2016, EFSA, Parma, Italy.

Folkedal, O., Pettersen, J., Bracke, M., Stien, L., Nilsson, J., Martins, C., Breck, O., Midtlyng, P., Kristiansen, T., 2016. On-farm evaluation of the Salmon Welfare Index Model (SWIM 1.0): theoretical and practical considerations. Animal Welfare 25, 135-149.

Fraser, D., 1987a. Mineral-deficient diets and the pig’s attraction to blood: implications for tail-biting. Canadian Journal of Animal Science 67, 909-918.

Gentle, M., 1986. Neuroma formation following partial beak amputation (beak trimming) in the chicken. Research in Veterinary Science 41, 383-385.

Holinger, M., 2017. Does chronic intermittent stress increase tail and ear manipulation in pigs?, From beak to tail – Mechanisms underlying damaging behaviour in laying hens and pigs (Satellite workshop ISAE-2017), Aarhus, Denmark.

Hughes, B., Duncan, I., 1988. The notion of ethological ‘need’, models of motivation and animal welfare. Animal Behaviour 36, 1696-1707.

Kjaer, J.B., 2009. Feather pecking in domestic fowl is genetically related to locomotor activity levels: implications for a hyperactivity disorder model of feather pecking. Behavior genetics 39, 564-570.

Korte, S.M., Olivier, B., Koolhaas, J.M., 2007. A new animal welfare concept based on allostasis. Physiology & behavior 92, 422-428.

Lorenz, K., 1978. Vergleichende Verhaltensforschung: Grundlagen der Ethologie. Springer-Verlag., Vienna.

Lorenz, K.Z., 1950. The comparative method in studying innate behavior patterns, Symposium of the Society of Experimental Biology, pp. 221–268.

McAdie, T.M., Keeling, L., 2000. Effect of manipulating feathers of laying hens on the incidence of feather pecking and cannibalism. Applied Animal Behaviour Science 68, 215-229.

Muir, W.M., 2003. Indirect selection for improvement of animal well-being., pp. 247–256 in Poultry Genetics Breeding and Biotechnology, edited by W. M. Muir and S. Aggrey. CABI Press, Cambridge, MA.

Newberry, R.C., Keeling, L.J., Estevez, I., Bilčík, B., 2007. Behaviour when young as a predictor of severe feather pecking in adult laying hens: the redirected foraging hypothesis revisited. Applied Animal Behaviour Science 107, 262-274.

Nicol, C., Bestman, M., Gilani, A., De Haas, E., De Jong, I., Lambton, S., Wagenaar, J., Weeks, C., Rodenburg, T., 2013. The prevention and control of feather pecking: application to commercial systems. World’s Poultry Science Journal 69, 775-788.

Noble, C., Jones, H.A.C., Damsgård, B., Flood, M.J., Midling, K.Ø., Roque, A., Sæther, B.-S., Cottee, S.Y., 2012. Injuries and deformities in fish: their potential impacts upon aquacultural production and welfare. Fish physiology and biochemistry 38, 61-83.

Parmentier, H., Rodenburg, T., De Vries Reilingh, G., Beerda, B., Kemp, B., 2009. Does enhancement of specific immune responses predispose laying hens for feather pecking? Poultry science 88, 536-542.

Pettersen, J.M., Bracke, M.B.M., Midtlyng, P.J., Folkedal, O., Stien, L.H., Steffenak, H., Kristiansen, T.S., 2014. Salmon welfare index model 2.0: an extended model for overall welfare assessment of caged Atlantic salmon, based on a review of selected welfare indicators and intended for fish health professionals.

Rodenburg, T., Van Krimpen, M., De Jong, I., De Haas, E., Kops, M., Riedstra, B., Nordquist, R., Wagenaar, J., Bestman, M., Nicol, C., 2013. The prevention and control of feather pecking in laying hens: identifying the underlying principles. World’s Poultry Science Journal 69, 361-374.

Rodenburg, T.B., Komen, H., Ellen, E.D., Uitdehaag, K.A., van Arendonk, J.A., 2008. Selection method and early-life history affect behavioural development, feather pecking and cannibalism in laying hens: a review. Applied Animal Behaviour Science 110, 217-228.

Schrøder-Petersen, D.L., Simonsen, H., 2001. Tail biting in pigs. The Veterinary Journal 162, 196-210.

Siegfried, N., Muller, M., Deeks, J.J., Volmink, J., 2009. Male circumcision for prevention of heterosexual acquisition of HIV in men. The Cochrane Library.

Simonsen, H., Klinken, L., Bindseil, E., 1991. Histopathology of intact and docked pigtails. British Veterinary Journal 147, 407-412.

Stien, L.H., Bracke, M.B.M., Folkedal, O., Nilsson, J., Oppedal, F., Torgersen, T., Kittilsen, S., Midtlyng, P.J., Vindas, M.A., Øverli, Ø., Kristiansen, T.S., 2013. Salmon Welfare Index Model (SWIM 1.0): a semantic model for overall welfare assessment of caged Atlantic salmon: review of the selected welfare indicators and model presentation, Reviews in Aquaculture, Oxford, UK, pp. 33-57.

Taylor, N.R., Main, D.C., Mendl, M., Edwards, S.A., 2010. Tail-biting: a new perspective. The Veterinary Journal 186, 137-147.

Tinbergen, N., 1963. On aims and methods of ethology. Ethology 20, 410-433.

Uexküll, J.v., 1909. Umwelt und innenleben der tiere, Springer, Berlin.

Uitdehaag, K.A., Rodenburg, T.B., Bolhuis, J.E., Decuypere, E., Komen, H., 2009. Mixed housing of different genetic lines of laying hens negatively affects feather pecking and fear related behaviour. Applied Animal Behaviour Science 116, 58-66.

Valros, A., 2017. Tail biting, in: Spinka, M. (Ed.), Advances in Pig Welfare, Elsevier.

Valros, A., Heinonen, M., 2015. Save the pig tail. Porcine Health Management 1.

van de Waal, E., Borgeaud, C., Whiten, A., 2013. Potent social learning and conformity shape a wild primate’s foraging decisions. Science 340, 483-485.

Van Dooren, K., 2013. Hoofdrol varkenshouder bij voorkomen staartbijten. [Main role for pig farmer in preventing tail biting]. Jan. 13, 2013. Available: Accessed 13-5-2016,

Van Niekerk, T., 2015. Overview feather pecking. Available at Accessed 11-2-2018.

Van Niekerk, T., In prep. Evidence based management of injurious pecking, Poultry Science.

Van Niekerk, T., Bracke, M.B.M., 2016. Pikkerij bij kalkoenen – Een stap terug naar het natuurlijk gedrag en soortspecifieke eigenschappen [Pecking in turkeys – A step back to natural behaviour and species-specific characteristics], Wageningen Livestock Research, Wageningen.

van Niekerk, T.G.C.M., Veldkamp, T., 2017. Insects for turkeys, Wageningen Livestock Research, Wageningen.

van Zeeland, Y.R.A., Spruit, B.M., Rodenburg, T.B., Riedstra, B., van Hierden, Y.M., Buitenhuis, B., Korte, S.M., Lumeij, J.T., 2009. Feather damaging behaviour in parrots: A review with consideration of comparative aspects. Applied Animal Behaviour Science 121, 75-95.

Wiepkema, P.R., 1987. Behavioural aspects of stress, in: Wiepkema, P.R., Adrichem, P.W.M.v. (Eds.), Biology of stress in farm animals: an integrative approach, Martinus Nijhoff, Dordrecht, pp. 113-133.

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Young, R.J., Carruthers, J., Lawrence, A.B., 1994. The effect of a foraging device (The ‘Edinburgh Foodball’) on the behaviour of pigs. Applied Animal Behaviour Science 39, 237-247.

Zagouri, F., Chrysikos, D.T., Sergentanis, T.N., Giannakopoulou, G., Zografos, C.G., Papadimitriou, C.A., Zografos, G.C., 2013. Prophylactic mastectomy: an appraisal. The American Surgeon 79, 205-212.

Zonderland, J.J., 2010a. Talking tails: quantifying the development of tail biting in pigs.

Zonderland, J.J., 2010b. Terug naar de Krulstaart, Veehouder en Dierenarts, pp. 21-23.

Zonderland, J.J., Bosma, A.J.J., Hoste, R., 2011. Financiële consequenties van staartbijten bij varkens. [Financial consequences of tail biting in pigs]. Report. Available: Accessed 1-5-2016, Wageningen UR Livestock Research, Lelystad.

Zonderland, J.J., Zonderland-Thomassen, M.A., 2016. Behavioural change by pig producers is the key factor in raising pigs with intact tails. The Veterinary Journal 211, 1-2.

Reading guide

This was blog post nr. 8 under the heading of: “Towards a common conceptual framework and illustrative model for feather pecking in poultry and tail biting in pigs – Connecting science to solutions”. It contains the following sections/posts:

  1. Introduction, specifying the need to compare feather pecking (fp) in layers and tail biting (tb) in pigs
  2. Terminology, specifying the various concepts involved in fp/tb.
  3. Overview of main similarities and differences between feather pecking and tail biting
  4. Farmer as a risk factor, emphasising, perhaps for the first time, that the farmer is a kind of ‘animal’ that is part of the problem (and the solution).
  5. Models, reviewing available conceptual models of fp and tb, as well as presenting a new ‘face model’.
  6. Disease framework, arguing that fp/tb may be regarded as a medical disorder, over and above being an abnormal behaviour per se.
  7. Evolution and domestication, emphasising the need to view fp/tb as a phenomenon an evolutionary and genetic background.
  8. References

The entire text (8 posts) can be downloaded as one pdf here.


These blog posts have been made possible by the Hennovation project (HORIZON 2020 ISIB-02-2014 project, Grant no. 652638).

Posted in Feather pecking, Laying hens | Tagged , , , , , | Leave a comment

Pig animation – Improved, branched chain design as proper enrichment for pigs

Pig animation: Rearing pigs in barren conditions reduces their welfare. Enrichment of pig pens is needed to allow the performance of species-specific natural behaviour like rooting. A metal chain provides rather limited enrichment, but when presented in an optimized way, may substantially improve the welfare of conventionally reared pigs in a most feasible way. The short metal chain can be optimize into the branched chain design. This is a long anchor-chain type chain reaching until floor level, with 2 or 3 shorter chain branches at nose height, and 1 such a branched chain being provided for every 5 pigs in the pen.

The underlying ideas are shown in the pig animation above and described in more detail in this book chapter:

Bracke MBM. Chains as proper enrichment for pigs (incl. supplement). In: Spinka M, editor. Advances in Pig Welfare: Elsevier (2017).


This chapter primarily compiles work in which the author (Marc Bracke) has been involved with providing science-based decision support on the question of what is proper enrichment material for intensively-farmed pigs as required by EC Directive 2001/93/EC. Proper manipulable material should primarily provide occupation (i.e. reduce boredom), and preferably reduce tail biting.

The RICHPIG model was built expressing enrichment value as a score on a scale from 0 to 10. Metal objects like short metal chains had the lowest score. Subsequently, the Dutch government banned the use of metal chains, and most Dutch pig farmers attached a hard plastic ball or pipe to the prevalent, short metal chain. Unfortunately, our on-farm observations repeatedly suggested that this ‘enrichment’ may have reduced pig welfare, rather than improving it as intended by the Directive.

So-called AMI (animal-material interaction) sensors can be used to (semi-)automatically record object manipulation by attaching a motion sensor to hanging objects. Exploratory data are presented to, directly and indirectly, record enrichment value. AMI-sensors may provide objective, flexible and feasible registration tools of enrichment value, but their application is still rather demanding.

That the enrichment value of short metal chains can be improved upon, e.g. by providing branched chains. Essentially, this entails making chains longer, preferably reaching until the floor, and making them more readily available in a pig pen. To facilitate the process towards proper enrichment the principle of intelligent natural design (IND) is proposed. IND entails organising a repeated selection process of the (currently) best-available enrichment material so as to gradually reduce pig boredom and enhance the opportunities for the rearing of pigs with intact tails. IND should start with basically all pig farmers implementing promising enrichment like the branched-chain design on their farms as soon as possible, followed by conducting small-scale on-farm experiments to compare and improve enrichment through sharing of available knowledge. Suggestions are given as to how and why this novel approach can be implemented to solve persistent animal-welfare problems like providing proper enrichment for intensively-farmed pigs.

Related posts:

Chains as enrichment for pigs (Book chapter with supplement)
Ketting als hokverrijking voor varkens (incl. link naar het supplement)
Branched chains as enrichment for pigs (technical description, pictures and video)
Future of intensive livestock farming: R.I.P?
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.

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An essential element of sustainable, circular farming: Integrity & a circular welfare economy

This blog post argues to recognize the importance of an often forgotten element of sustainability: Integrity. In particular, I will argue that honesty and emotions are necessary elements of a sustainable, circular agricultural economy.


Sustainability is often perceived as triple p: People, planet, profit. One has to ‘twist’ these concepts in order to be able to fit in animal welfare. Some would say welfare is part of people, for others it is planet, or even just a matter of profit. Thus, in the case of pigs 4 p’s have been proposed as well: people, planet, profit & pigs.

Circular economy

Recently more attention is being payed to the closing of nutrient and (waste) product cycles. In particular we must reduce the use of fossil fuels (e.g. as fertilizers) in the agricultural economy. Ideally, the main waste product of livestock farming, manure, should be used to fertilize the soil on which crops are grown to feed both people and animals in a way that no nutrients get lost. This generates a circular pattern (“cradle-to-cradle”): manure->soil->plants->animals & people->manure.

Animal welfare

Animal welfare constitutes a potential problem for the concept of sustainability, and in particular for the concept of a circular agricultural economy. It does not seem to fit in naturally. Why would animal welfare matter? Of course the immediate answer is that feelings matter. But why do feeling matter in ppp or in circular agriculture? That is not immediately evident.

Technical solutions

Often a perceived lack of sustainability of current livestock farming is met with the suggestion that technological solutions may fix the problem. Accordingly we have been designing low-emission buildings, for example, and high(er) welfare systems. Similarly, we may produce locally to reduce transport driven by fossil fuels, and we may contemplate economic fixes like welfare schemes or a meat tax. Yet, despite continued efforts to find technological fixes, societal concerns over a deficient agricultural system continue to increase.


What is often overlooked in thinking about sustainability is the crucial role of integrity. Integrity can take different forms. When a pig’s tail is removed in order to adapt it to the system, that can be perceived as a violation of the pig’s integrity. Another almost self-evident lack of integrity, human integrity in this case, was the company ChickFriend, who was illegally using pesticides (fipronil) to treat red mites in poultry, thus contaminating eggs. However, a deficient integrity can be identified when producers or consumers are showing wilful blindness to welfare, environmental issues or public health concerns associated with livestock farming. Dishonesty and telling only part of the truth (even to oneself) are also indicative of inadequate human integrity leading to compromised sustainability.


In each of these sustainability areas (animal welfare, environment, public health) the key problem is welfare, that is both the welfare of humans and the welfare of non-human animals. An important distinction within welfare is the distinction between positive feelings (pleasure, happiness) and negative feelings (pain and suffering). When there are sustainability issues there is ‘pain’: animal-welfare ‘pain’, landscape ‘pain’, waste ‘pain’, climate-change ‘pain’, loss-of-biodiversity ‘pain’,  public-health ‘pain’.  Such ‘pains’ hurt, but ignoring and hiding or denying the existence of these pains is even more harmful. By contrast, positive feelings are more delightful and able to flow freely between individuals when not hampered by an overriding ‘pain’.

Circular welfare economy

What I propose here is that a sustainable, circular economy should not just concern closed nutrient cycles, but also closed welfare cycles. A circular welfare economy for livestock farming implies that the positive and negative feelings in farming and in society can freely ‘flow’ between animals and people. By taking proper care of the animals farmers convey positive welfare to the animals. In turn happy animals convey positive feelings to farmers, and to consumers and citizens. Only such a closed, circular welfare economy can be sustainable.

Not sustainable

The problem with the current agricultural economy is that she is not sustainable, not just because there are technical problems with animal welfare, environmental impact and public health, but in particular because the welfare cycles cannot close. Feelings cannot freely flow between individuals. This is because there is a (perceived) lack of honesty and truthfulness in current livestock farming.


Current livestock farming has a tendency to polarize society. Since it is based on externalising costs it has a strong tendency to show reduced integrity: a lack of (complete) truthfulness to oneself and to others about aspects that are not promoting sales or image. These issues remain hidden until they are discovered, and then we have another scandal. This pattern has been showing a tendency to repeat itself like earth quakes as a consequence of friction between tectonic plates. The scandals/earth quakes generate an increasing distrust and polarisation, and this has a tendency to further enhanced lack of human (and animal) integrity. In other words, a deficient level of integrity has self-reinforcing and hence self-destructive tendencies.

Integrity as the solution

In order to improve agricultural sustainability we must not only look for technological fixes. We must also fix ourselves. In particular we need to promote enhanced integrity, i.c. the ability to be open and honest, not only about favourable issues, but also about issues that are opposing one’s immediate self-interest. Without integrity polarisation between farmer interest groups and sustainability interest groups will continue to raise societal conflict and frustration. Instead, we need more altruism and less selfishness, in particular related to livestock farming. We need to find ways in which all feelings, both the positive and the negative ones, can flow freely between individuals. A circular welfare economy is needed to complement (or even ‘absorb’) the circular nutrient economy as a desirable sustainable food-production future. To make this possible, enhanced integrity, of both animals and people, is absolutely essential.

Circular welfare economy
See also the related column (in Dutch) and my post on How can we feed the world?

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How would I spend 10 billion to improve the Netherlands? I’d burn it.

How would I spend 10 billion € to improve the Netherlands? NRC newspaper asked readers to write a short answer to this question. This is my answer:

Seven opinionators already gave their answer (NRC 16 aug, 2017). Each had a proposal in line with his/her own interests. But that way we’ll never get there! Ten billion to improve the Netherlands? That’s a most interesting question. Because yes, even though we may not always want to see it, there is a lot to improve in our nice little (tax) paradise. But why would we spend 10 billion to improve only the Netherlands? Everything is connected by trade and the internet. We really have to be much more ambitious. Let’s try to improve the whole world! But how? That requires identifying the core of the problem. And that core, my dearest reader, is us, and especially our enormous greed for money. It repeatedly leads to scandals. Just think about the banks, Volkswagen and the fipronil fraud. But don’t be mistaken. The desire for money is in all of us. That’s why we are gradually heating the whole world, like frogs in a pot of water. We should jump out of the pot as soon as possible. We must make a leap of faith! We could all become peaceful Buddhists or something like that. It’s free! We should use the 10 billion to set an example to the rest of the world: We Cannon but a Better world, so we burn the 10 billion euros, like illegal ivory, and start anew.

Posted in Ethics, Future, Geen categorie, Happiness, Justice, Money, Objectives, Politics | Tagged , , , , | Leave a comment

Future of intensive livestock farming: R.I.P?


At the moment the future of intensive livestock farming is intensively debated in the Netherlands. The province of Noord-Brabant may be the first to actually limit the number of farm animals. The Dutch meat inspection (NVWA) is heavily criticized for more or less condoning illegal slaughter practices, and veterinarians are calling for reform.

It is a very difficult debate, because the economic and emotional interests at stake are extremely high. Perhaps in such a case an artistic impression may help put argument and emotion in perspective.

Animation: R.I.P.?

The animation below may illustrate the development of intensive livestock farming from past to future. It shows the evolutionary history of the pig, the (potential) ‘evolution’ of the intensive housing environment (improved environmental enrichment), and the end of the pig (R.I.P.). The pig, however, may also be regarded as the personification of the farmer or the livestock sector itself.

Less philosophical postscript

Rearing pigs in barren conditions reduces their welfare. Enrichment of pig pens is needed to allow the performance of species-specific natural behaviour like rooting. A metal chain provides rather limited enrichment, but when presented in an optimized way, may substantially improve the welfare of conventionally reared pigs in a most feasible way.

See also the related posts:
Pig animation – Improved, branched chain design as proper enrichment for pigs
Chains as enrichment for pigs (Book chapter with supplement)
and this post (partly in Dutch): Ketting als hokverrijking voor varkens (incl. link naar het supplement).

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Reflection on running science as a business

Would it be proper to run a scientific institute as a business, or would it be a category mistake?

Category mistake

A category mistake is a rather fundamental mistake concerning the true nature of a concept. An example would be to say that the color of bread is 100€. This is a category mistake, not because 100€ is too expensive, but because the color of an object cannot be expressed using a monetary value. Could it similarly be a category mistake to view science as a business?

Science expensive

Like the exceptionally expensive loaf of bread in the example above, science is generally exceptionally costly. This has everything to do with the nature of science for it generally requires highly specialized personnel applying rigorous methods in unique (non-routine) ways in order to generate/accumulate highly reliable and verifiable knowledge. However, science may also be perceived as inefficient.

Science as business

Thus, science has been exposed to increasing pressure to enhance its own ‘production efficiency’. To meet this objective science is increasingly viewed as if it were a ‘normal’ business. This means that a scientific institute may, for example, have front-office managers who have been trained to persuade ‘customers’ in the ‘market’ to commission research. However, it may be questioned whether it is proper to view the production of a scientific report as if it were a commercial product.

The nature of business

Efficient production is a hallmark of commercial business. Competition between businesses in a largely free market tends to stimulate efficiency in meeting market demands. In a free market cost is determined by the The true nature of business is nature, i.e. its adherence to the laws of nature, in particular the law of survival of the fittest. Thus, the business model may help reduce the cost of science by enhancing its efficiency.

A business opportunity in science

Here I want to zoom in on a rather hypothetical business case in science. Suppose a scientist is in the unique position to require an exceptionally small effort, e.g. the equivalent to 100€ of research time, to enable a ‘business-customer’ to save a lot of money. Say the return on investment for the customer could be 100.000. However, if our scientist would be an entrepreneur he should see this as a business opportunity and he may then be tempted to charge perhaps 1000 or even 10.000 times the required amount. This would enhance the profitability of science while still leaving a respectable profit of 9.9 or 9.0M € for the customer.


Several concerns arise from adopting such a frame of mind in science. Firstly, this hypothetical example is counterfactual in at least two respects.

I would personally be tempted to regard it as immoral to charge substantially more, even if it would only be 100 times the required amount. This is because science is mostly very costly, and science often has difficulty meeting the true needs of  society, e.g. in terms of helping society solve urgent disputes, like those concerning animal welfare and sustainability. I’m most reluctant to accept that generally most expensive scientist would also be greedy when the occasional opportunity arises, rather than regarding it as returning an occasional favor to society, e.g. by helping a customer make a profit based on scientific innovation.

Improper business

However, there is another, more fundamental concern in perceiving science as a business. In many ‘normal’ businesses it would be no problem whatsoever to charge a much higher rate. Normal business generally even commands doing so. It would just be a matter of taking advantage of a business opportunity. However, it wouldn’t be proper for all businesses to behave this way. Perhaps it cannot be seen as an acceptable practice in any kind of business, because it appears to violate a moral sense of justice and honesty.


Suppose a hungry customer enters a bakery shop just before closing time. The last loaf of bread may be worth perhaps as much as 100€. Yet it wouldn’t be a good idea to charge that much to a hungry or wealthy customer. He would probably be getting very angry, and rightly so. For this is not the kind of business morals we would accept as consumer-customers. It just wouldn’t be fair.


An important difference between science and a bakery is that the effort it takes to do science is often not as transparent. In this respect, a scientist is more like a dentist. For a dentist it is generally fairly easy to drill some holes in healthy teeth, just to make some extra money. But that wouldn’t be an acceptable ‘business’ either.


A scientist, like a medical professional, is supposed to be thoroughly reliable. Honesty and transparency are key values of science. Without these values science may make itself impossible. If a scientist is charging excessive amount of money, just because it is possible, he may get away with this if he has no problem in pretending it took a lot of work. But it would compromise the scientist’s honesty towards the paying ‘client’. And this is bound to generate a personal dilemma regarding (scientific) integrity, if science were run as a ‘regular’ business.

Natural selection

Now, of course, it is possible to solve this problem by natural selection, as is generally the case in business. If you want to be honest, just don’t aspire becoming a regular salesperson. But I am not so sure if the same should apply to a scientist.

No true category mistake?

In other words, seeing science as a bussiness may compromise (scientific) integrity. In the ideal world business should be honest and reliable too.  If so, running science as a business would not be a true category mistake. However,  in as far deception and ‘alternative facts’ can accepted as part and parcel of ‘normal’ business, to that extent perceiving science as a’normal’ business would be a rather serious category mistake.


Other professions generate similar concerns. Here is a link to a video clip (in Dutch) where a journalist uses children to generate an ‘alternative fact’ about the taste of vegan meat (original clip here). Such a deliberate construction of alternative facts may well be regarded as a punishable crime. In any case scientists and jounalists should be most reluctant to become engaged in the generation of such fake realities for the sake of doing more ‘profitable business’.

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How (not) to excel in doing well?

Well, well, well

People sometimes think we are rational animals. Like animals we behave, but unlike animals we have the capacity to behave (more) rationally. And not just that: with rationality comes our more or less unique capacity of being moral. So we can do well as well. But if we are rational and if we can do well, we can also excel in doing well. We may even conjecture that this is what constitutes the summum bonum of human wel-fare, doing well well. A recent trend in philanthropy, the art of doing well, proposes to do just that: to do well as effectively as possible. It is called effective altruism.

Intensive livestock farming

The idea of doing well well is not exclusive for philanthropy. In fact, it is the corner stone of rationalised agriculture. After WWII doing well well implied making sure there would be no more hunger and thus no more war (in the Western world). To achieve this rationalised agriculture was promoted, resulting in affordable food produced in large quantities for a growing population. However, the principle of rationalised production efficiency which made this possible also transformed traditional livestock farming into what has become known as bio-industry, one of the main societal concerns in the Western world at present. Lessons learnt from modernised livestock farming may thus be of value for the art of doing well well.

Slumbering collateral damage

One of the main lessons of intensive farming is that being successful carries a risk. Adopting maximised production efficiency as a governing principle in farming brought great progress. At the same time, however, it seems to have had a tendency to induce slumbering problems, like collateral damage that may be ignored and thereby grow out of control.


Maximised production efficiency, and doing well efficiently, are concepts within the paradigm of analytical reasoning. Its prime mechanism is to focus strongly on (solving) a problem (logical) step by (logical) step. Problems get solved more easily when they are simplified. When ammonia emissions from livestock buildings were becoming a concern in the eighties it was clear that a solution was to separate urine from faeces as quickly as possible. Innovative designs led to the construction of barns with smooth flooring. Unfortunately, this also resulted in animals with broken bones. In this example the secondary problem is rather obvious, but other problems, like climate change, antibiotic resistance and chronic disease, were less well detected, probably because we had an interest in turning a blind eye. Thus these problems could spread silently like defective genes associated with using a ‘superior’ bull in dairy farming.

a well

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Publications on AMI sensors

This is a short list of scientific publications in which I have used AMI sensors. AMI stands for animal material interactions. AMI sensors can take various shapes and forms. In some way or other AMI sensors record the amount of interaction pigs have with enrichment materials for pigs. Mostly this concerns hanging toys like chains and ropes with or without suspended materials like pieces of wood. Below the list you can also find the abstracts. So far the use of AMI sensors is (mainly) restricted to application for scientific purposes, eg to measure the value of (different aspects of) enrichment materials (directly or indirectly), the effect of tail-biting ointments, and abnormal and/or sickness behaviour. A blog post on AMI sensors and the future of pig farming can be found here.


To validate (further) a semantic model called RICHPIG, which was designed to assess enrichment materials for pigs, a study was conducted to examine the importance of three assessment criteria, namely destructibility, hygiene and sound. These material properties were studied using a specially constructed object consisting of a piece of sisal rope, metal wire and three fixed chain links hanging in the pens. The object was considered to be not destructible (ND), hygienic (HY) and not making sound (NS). After a habituation period of 18 h treatments were applied in that the object was (or was not) made destructible with a partial cut in the rope (DE) and/or was soiled with excreta (not hygienic, NH) and/or was allowed to make a tinkling sound by releasing the chain links (SO). The three treatments were applied in a 2 × 2 × 2 factorial design on a commercial farm in seven replicates using seven different units containing eight pens per unit. At five moments in time, ranging from 18 h before until 1 h after treatment, a range of behaviours was recorded including the frequency-related parameter AMI (animal–material interactions) and four intensity-related parameters. Repeated measures ANOVA’s showed significant effects of time and hygiene as well as interactions between time and hygiene, between time and destructibility and between destructibility and sound. Soiling (NH) significantly decreased, and destructibility (DE) significantly increased attractiveness, while sound (SO) was not significant. Only moderate correlations between AMI and the four intensity-related parameters were found (median r = 0.41, all P < 0.05), indicating that frequency-related parameters alone may not suffice to determine behavioural importance for animal welfare.

This study showed that it is in principle possible to study material properties independent of material type and that it is in principle possible to measure behavioural intensities on a commercial farm. Furthermore, the finding that hygiene and destructibility were more important for pigs than tinkling sounds provided preliminary support for the RICHPIG model.

In search for a test measuring positive emotions in pigs for application in on-farm welfare auditing, three small experiments were conducted to examine the sensitivity of a novel object test designed to measure the pigs’ (residual) need/motivation for enrichment. In the experiments the interactions with a novel piece of rope were measured at pen level using a so-called AMI sensor (AMI: animal–material interactions). Measurements were taken at several points in time over a 1–2 h period in order to test the effects of marginal enrichments, namely the provision of a jerrycan canister (Experiments 1a and 1b) and the provision of some sawdust and/or removal of the metal chain (Experiment 2).

The first experiment was replicated in, respectively, 8 and 15 matched pairs of pens with groups of about 11 growing pigs per pen. A jerrycan was provided in one pen of each pair as of the day before the novel object test. In the first replicate (Experiment 1a) only a main effect of time was found in that AMI decreased over time. In the second replicate (Experiment 1b) the provision of the jerrycan significantly reduced AMI. A sign test also confirmed this effect for the data in the first replicate. The recent provision of a jerrycan, therefore, marginally, but statistically significantly, reduced AMI in the novel object test.

Experiment 2 was a 2 × 2 factorially designed study conducted in 40 pens containing groups of 24 weaned piglets. Factors were sawdust provision and chain removal. The four treatment combinations were applied as of 45 min before the test. In addition to a main effect of time, it was found that AMI significantly increased when the chain had been removed (P = 0.006), and that the provision of sawdust tended to depress AMI at 10 min, while tending to enhance AMI at 30 min (interaction between time and sawdust provision: P = 0.097).

The results indicate that the novel object test may be used to detect relatively minor differences in environmental enrichment.

Tail biting is a most serious welfare problem in pigs raised for slaughter. In instances of an outbreak of tail biting, scientists have recommended that farmers take measures such as removal of affected animals, provision of enrichment materials and application of repellents to the pigs’ tails. However, no scientific study has ever confirmed the efficacy of any of these suggestions in counteracting an ongoing outbreak. Here, the efficacy of two repellent ointments, Dippel’s oil and Stockholm tar, were examined in a tail-chew test. For this, a novel piece of nylon rope was used as a tail model to measure biting behaviour semi-automatically in 24 single-sex groups of growing pigs (total 264 pigs). Repeated measures analysis showed no effect of time, gender or unit (12 pens per unit), but a highly significant effect of treatment, in that both Stockholm tar and Dippel’s oil significantly reduced rope manipulation compared to controls. These results suggest that Stockholm tar and Dippel’s oil may be effective in reducing tail biting. The approach taken may be valuable in further testing of strategies to reduce tail biting and improving pig welfare.

Injurious behaviours in pigs may involve persistent or forceful biting in specific body parts and may result in wounds of the pigs’ tails, ears, flanks and legs. Such behaviours, which may lead to progressive tissue damage, are difficult to counteract.
On a commercial farm 22 groups of pigs with wounds on flanks (n = 16) and tails (n = 6) were matched with 22 control groups without wounds. All groups were provided with a novel rope, applied as a ‘tail chew test’. Interaction with the rope was recorded semi-automatically about 45 and 120 minutes after introduction of the rope. Statistical analysis showed significant decrease of interest in the rope over time and significantly elevated interest in the ropes in pens containing wounded animals (median number of pulls per minute in control pens, flank-biting pens and tail-biting pens were 7.8a, 10.2b and 14.3b respectively, where superscripts indicate significance levels (P < 0.001).
These results suggest that flank biting and tail biting increase exploration and destructibility in pigs. The approach taken is valuable in further understanding strategies to reduce injurious behaviours in pigs and improving pig welfare, e.g. by providing enrichment materials.

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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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