Tag: Health

Towards a common conceptual framework and illustrative model for feather pecking in poultry and tail biting in pigs – 5. Models

This is post 5 on “Models” 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.

5. Models

Table 3 shows a list of various models/figures that have been proposed to clarify feather pecking (fp)/tail biting (tb), including the recent model proposed by Brunberg et al. (2016). Our focus here was to compare models, esp. models originating from Wageningen University Research, in search for potential improvements. Not all models have been included in Table 3. For example, Valros and Heinonen (2015) propose a modified bucket model where the bucket is filled with acute and/or chronic stressors (cf also Valros (2017)).

Some model illustrations.

 

Since copy-rights are a problem for representing models, below a selection is given of models for which Wageningen UR (already) has the copy-rights. Other models can be obtained via the cited references or the internet. E.g. an example of the psychohydraulic model (Lorenz, 1950; 1978) can be found here.

Figure 7.3 below shows the tail biting (tb) model by Zonderland (2010a) (Fig. 7.3, p. 138).

The conceptual framework for tb originating from Bracke (2008) (reprinted in (Bracke, 2017)) is shown in Figure 1 below. This model was designed to construct the RICHPIG model (decision support system) to assess/calculate the welfare value of enrichment materials for pigs.

Figure 1. Schematic representation of the conceptual framework for assessing environmental enrichment for pigs. EMat: Enrichment material; AMI: animal-material interactions; I: Istwert, the environment as perceived by the animal; S: Sollwert, set point or norm (modified homeostatic model after Wiepkema (1987) and (Anonymous, 2001)). (Figure from Bracke (2008), permission granted by UFAW) (reprinted from (Bracke, 2017)).

Citation from Bracke (2017) relating the model to the principle of communicating vessels:

“Progressive feedback loops in the framework indicate that the animal’s welfare is good when proper enrichment satisfies the pigs’ need to explore and forage. When the enrichment is deficient, the animals will redirect their attention and show pen- and pen-mate directed behaviour. Note that this may imply a mechanism resembling the principle of communicating vessels (connected containers filled with liquid; see Wikipedia (2016c)). In accordance with this principle pigs may distribute their (motivation for) exploratory behaviour (the liquid) depending on the quality of the manipulable ‘materials’ available to them (cf Bracke et al. (2012)). Eventually, an outbreak of tail biting may occur, potentially evoking a positive feedback loop (an escalating outbreak) leading to cannibalism when no ‘proper enrichment’ is provided buffering and/or eliminating the (primary) cause/stressor.” (End of citation).

In the communicating-vessels model, for which we found some empirical evidence in pigs (Bracke, 2017), vessel size may change due to animal-properties like genetics; but also e.g. enrichment-based and other risk factors.

In the case of fp in poultry, in a classic paper Newberry et al. (2007) questioned the assumption of communicating vessels underlying the hypothesis that fp is redirected foraging behaviour as proposed earlier by Blokhuis (1986). Newberry et al. (2007) showed that birds with high levels of ground pecking as chicks were more likely to develop high levels of fp as adults compared to low ground pecking chicks. However, the high ground pecking chicks also continued to show high levels of ground pecking as adults, shedding doubt on the theory that fp would replace ground pecking.

Under ‘mechanism’ Van Niekerk (2015) presents both a balance model and a tipping-bucket model for fp (see also Van Niekerk (In prep.)). The bucket model was modified from a tb model originally proposed by Vermeer in Bracke et al. (2012). The main problem of the tipping-bucket model is that it suggests that fp/tb cannot stop, cannot be made undone (or perhaps only via an external ‘force’, e.g. a farmer taking adequate measures to correct the problem). Perhaps the model could be improved, e.g. by making a tumbler-type tipping bucket, such that it can be emptied, and then may restore its original position. However, this revised tumbler model would still be deficient in that post fp/tb set points are not the same as before (as a tumbler would suggest). Another option might be a series of buckets. Once tipped, the next bucket could stay down, with the next bucket being smaller, such that the next tipping point would be reached sooner, with preventive measures reducing the flow of water into the bucket. This would solve the issues just mentioned, but it would seem to be a somewhat ‘artificial’/non-parsimonious model.

Tipping bucket model of feather pecking

Figure 2. Tipping-bucket model of feather pecking (Van Niekerk (2015); modified after Bracke et al. (2012)). 

Balance of causes of feather pecking

Figure 3. Balance model (Van Niekerk (2015), from http://www.henhub.eu/fp/mech/).

Perhaps the balance model could be modified to a balance between ‘fixed’ risk factors on the one scale and management (farmer effort) to reduce tb/fp risk on the other scale of the balance. However, the symmetry in disbalance suggested by the model does not seem to make sense: too much pressure on one side does not have the same effect as too much pressure on the other side. Also, fp/tb does not seem to be (totally) reversible: inducing fp/tb by removing a bit of enrichment cannot be undone by adding the same bit of enrichment (at least not shown). Also, to date no studies are available showing reversibility by adding other factors (e.g. inducing tb/fp by poor litter quality and then ‘treating’ this problem by adding e.g. better feed, etc.).

 

The next figure (Figure 4 below) shows a newly developed ‘face’ model aimed at incorporating the different types of animal involved (actor, victim, neutral), as well as emphasising the role of the farmer (as a kind of ‘actor’) in dealing with a fp/tb problem. The farmer is important for prevention and treatment of fp/tb. The emergence of an animal-actor is necessary to start fp/tb, but the responsiveness of the victim also plays a roll. For example, a victim may more or less effectively avoid becoming a victim and respond more or less in a way that leads to escalation of an outbreak. While a learning process may have transformed actors into individuals predisposed to show the abnormal fp/tb behaviour again at a later stage, similarly, at some point victims may show learned helplessness (which may also more or less permanently alter their behavioural predisposition).

Figure 4. New ‘face’ model of feather pecking (fp)/tail biting (tb), showing its multifactorial nature (‘left ear’), the role of different types of animal (actor & victim (‘eyes’), neutral (‘mouth’)), array of responses (‘right ear’), as well as the role of the farmer (‘nose’) in dealing with the problem. Both positive and negative feedback loops (‘glasses’ around the eyes of the face) are involved. Evolution and life history (‘hairs’) determine the set points of the individuals (animals and farmer). The comparators (‘pupils’ etc.) are (more or less) equivalent to welfare (smiley, balance, bucket and marble run) as indicated in the ‘necklace’ below the face. TIM: tail in mouth; OCTB: obsessive-compulsive tail biting; p.m.: pen mate; i.r.t.: in relation to. (Modified after (Bracke, 2017), and incorporating elements of the other models shown above, i.c. the balance and bucket models).

Reading guide

This was blog post nr. 5 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.

Acknowledgements

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

 

Towards a common conceptual framework and illustrative model for feather pecking in poultry and tail biting in pigs – 6. Disease framework

This is post 6. “Disease framework” 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.

6. Disease framework

Brunberg et al. (2016) characterise feather pecking (fp)/tail biting (tb) as an abnormal behaviour. However, they do not frame it as a disease. This section deals with the question whether fp/tb may/should be regarded as a disease, i.e. as a medical disorder, in particular a mental/behavioural pathology.

Of course, a lesion of the bitten/pecked animal (victim) can be regarded as a health disorder. However, when fp/tb is primarily seen as a behaviour of the actor, and not as a medical disorder, then adequately understanding the behaviour requires addressing the 4 why questions proposed by Tinbergen (1963). That is, a behaviour is sufficiently understood if we understand its mechanism/causation, its function/adaptation, its evolution/phylogeny (over generations) and its development/ontogeny (over the course of the individual’s life).

These aspects have been covered for the most part by Brunberg et al. (2016). However, aspects related to the importance and treatment of fp/tb were only marginally addressed.

When we were looking for a format to present the available information about fp at the www.henhub.eu/fp website, which was intended to inform farmers and the public, we decided to use the framework commonly used to describe medical disorders (Van Niekerk, 2015). This implies a characterisation of aspects like signs/symptoms/diagnosis (kinds of fp/tb), pathophysiology (mechanism), prevention, treatment and (economic) importance of fp.

Aspects related to (differential) diagnosis and pathophysiology may, for example, deal with the question whether ear biting, ear necrosis and flank biting are to be regarded as forms of (i.e. having a causation (and treatment) similar to) ‘tail biting. Conversely, Taylor et al. (2010) identified three types of tb in pigs: two-stage, sudden forceful and fanatic. These may be 3 different syndromes, all labelled ‘tb’.

The importance of the fp/tb problem does not only concern production losses and financial implications. It may also concern legal, psychological and ethical aspects such as animal integrity, the attitude regarding ‘blood’ in the pen, aversion to sustainability pressures among farmers, e.g. due to fear of (over-)regulation. As to the legal relevance, both tail docking and beak trimming have been banned in the EU some time ago, yet despite this farmers have mostly continued to perform these procedures routinely (and they were repeatedly being granted exemption to do so).

Once fp/tb is regarded as a problem that needs to be solved, the disease framework clearly has added value. For example, it is important to realise/understand that the management of risk factors applied for the purpose of prevention of fp/tb is not necessarily the same as applying them for the purpose of curative treatment, i.e. counteracting an outbreak of fp/tb. E.g. it is likely that more enrichment is needed to treat than to prevent fp/tb.

In the commercial practice of intensive livestock farming fp/tb are common problems, esp. when routine mutilations were no longer allowed. However, that does not imply that it is normal for the animals involved to show such abnormal behaviours. Fp/tb have been labelled so-called technopathies, i.e. pathological behaviours associated with agro-technologically designed living conditions. A common perception among applied ethologists, namely, is that there is a wide discrepancy between the animals’ living conditions in intensive livestock farming and the animals’ environment of evolutionary adaptation. That is, the living conditions are not normal. They are likely to overtax the animals’ control systems, thus leading to behavioural pathology/disorders. From an evolutionary perspective fp/tb is not part of the adaptive behaviours in which poultry/pigs deal with a variable environment. Instead these abnormal and injurious behaviours result from a frustrated need to perform rather species-specific foraging behaviours (scratching/rooting) for substantial periods of time, leading to boredom in relatively barren environments imposed under intensive livestock conditions.

The fact that these mutilating, harmful social behaviours (fp/tb) also (seem to) require preventive surgical interventions/mutilations (beak treatment, tail docking) strongly indicates that the label ‘medical disorder’ would seem to be appropriate. In humans self-harm and harmful social behaviour have been classified as (symptoms of) medical disorders, e.g. self-mutilation  in borderline patients and antisocial/dissocial personality disorder respectively. Preventive mutilation also implies an infringement of the animals’ integrity (a moral concern). It also indicates that the environment is not suited for the animals. Examples of preventive mutilations in human medicine are (religious) circumcision (e.g. for religious reasons or to prevent HIV in sub-Saharan Africa (Siegfried et al., 2009)), preventive mastectomy in women who are BRCA1 or BRCA2 mutation gene carriers (Zagouri et al., 2013), and prophylactic colectomy or even Whipple procedure (a major surgical operation involving the removal of the head of the pancreas, the duodenum, the proximal jejunum, gallbladder, and part of the stomach), e.g. in case of familial adenomatous polyposis (i.e. to prevent intestinal cancer). Whether in humans or animals, preventive surgery, even if intended to prevent ‘greater harm’ later in life, is not to be regarded as ‘normal’. E.g. in the case of pigs and laying hens the preventive mutilations have been associated with chronic ‘phantom’ pain because of neuroma formation (pigs: (Simonsen et al., 1991; Di Giminiani et al., 2017); poultry: (Gentle, 1986)). And, while the mutilation may solve the problem of future victims, in doing so it masks the problem (stress, mental pathology) that gives rise to neutrals becoming actors that engage in destructive, harmful social (or sometimes self-mutilating (van Zeeland et al., 2009)) behaviours. To paraphrase an early Dutch researcher of tail biting in pigs, Gerrit van Putten: the pig’s tail is a thermometer of animal welfare, which was discarded when the “temperature” became too high, i.e. the tails were docked rather than that housing conditions were improved. Also regarding the practice of preventing fp/tb using routine mutilations, it has been pointed out that these procedures are not fully effective. E.g. Zonderland et al. (2011) estimated a prevalence of 2.12% tail biting despite (very short) tail docking on Dutch farms.

Another indicator for viewing fp/tb as a medical disorder is the fact that fp/tb outbreaks lead to injuries (wounds), which may even escalate into cannibalism and/or death due to secondary infections of the wounds. This (progressive) loss of normal functioning and lack of homeostasis have typically been regarded as indicative of disease, esp. since these are also of economic significance to the farmers (Zonderland et al., 2011).

However, fp/tb is not just a problem because of wounds inflicted on the victims. As Brunberg et al. (2016) rightly point out, the (acute pain of the) victim is not the only welfare concern. An important part of the (more chronic) welfare problem concerns the stressors/behavioural deprivations that lead neutral animals to become actors of fp/tb. Fp/tb, therefore, is not just a medial disorder because of the clinical wounds (and surgical prevention practices), but also because of the likely mental disorder leading to the abnormal fp/tb behaviour shown by the actors. Taylor et al. (2010) distinguished three types of tail-biting pigs: two-stage (where tail biting is preceded by more gentle tail-in-mouth (TIM) behaviour), sudden forceful (without prior TIM, e.g. to get access to the feeder) and fanatic tb. The latter was also labelled as ‘obsessive’ and ‘persistent’, and may thus be classified tentatively as an ‘obsessive-compulsive’, which seems to come close to labelling this type of tb as an obsessive-compulsive mental disorder.

Formerly, harmful social behaviours like fp and tb have been labelled as ‘vices’. However, that label implies seeing the actors as a kind of criminals. In fact, and esp. the medical framework, would turn the actor into a kind of victim too, i.e. a victim of inappropriate/depriving/stressful living conditions of intensive farming.

A related point indicative of fp/tb being a medical disorder is the fact that fp/tb problems tend to spread in a pen (and perhaps also across pens). This may make fp/tb resemble an infectious disease/epidemic. In other words, fp/tb has disease-like properties: the behaviour has a tendency to escalate into a fp/tb outbreak. While it may be that novelty and reward (the taste of blood) may account for the frantic and ‘contagious’ appearance, the behaviour seems to be ‘contagious’, in that other animals in a pen/enclosure may acquire the behaviour once the first animal has started to engage in it. In this respect, it may be noted, that esp. in pigs often the pen is regarded as an ‘experimental unit’, while it remains to be shown that pigs in neighbouring pens remain unaffected by (the arousal caused by) ongoing tb.

A further disease-like property of fp/tb is the role of stress in the aetiology of the problem.  Many diseases are aggravated by common stressors like high stocking densities and limited access of food or a poor climate, e.g. because stress may reduce the immune response needed to combat the disease. Similar stressors also play a role in triggering fp/tb. However, the underlying pathophysiological mechanism may not be the same, as stimulation of the (humoral) immune response has been shown to predispose (rather than inhibit) fp in laying hens (Parmentier et al., 2009).

Finally, it may be pointed out that most major textbooks describing the diseases of poultry/laying hens and swine/pigs already have a chapter or section on fp and tb respectively. In that respect, a start has been made to recognise fp and tb as a medical/mental/behavioural pathology. The conclusion of this section, we believe, justifies a more proper recognition of fp/tb as a medical disorder, i.c. a mental disorder, in the future.

Reading guide

This was blog post nr. 6 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.

Acknowledgements

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

From beak to tail – Mechanisms underlying damaging behaviour in laying hens and pigs (Satellite workshop ISAE-2017)

August 7, 2017 a very nice one-day meeting was held in Aarhus (DK) to discuss feather pecking in laying hens and tail biting in pigs.  The meeting was a joint initiative of FareWellDock and GroupHouseNet. A Skype4business connection made it possible for about 10 external participants to join the meeting in addition to the 60 delegates present in person.

Programme:

Opening of the meeting, introduction and networking session,
Anna Valros, Sandra Edwards

9:50-11:00 Theme 1: Mechanisms underlying the link between health and damaging behaviour
Invited speakers: Janicke Nordgreen (pigs), Jerine van der Eijk (poultry)

Mini research seminar
≥ Lisette van der Zande: The estimation of genetic effects of tail damage on weaned pigs and its influence on production traits
≥ Anja Brinch Riber: Link between feather pecking and keel bone damage
≥Mirjam Holinger: Does chronic intermittent stress increase tail and ear manipulation in pigs?
≥Laura Boyle: The effect of removing antibiotics from the diets of weaner pigs on performance of ear and tail biting behaviours and associated lesions

11:00-11:20 Coffee/tea break
11:20-12:20 Theme 1 continues: Group and plenary discussion, Anna Valros
12:20-13:20 Lunch break
13:20-14:30 Theme 2: Predisposing factors for damaging behaviour during early development
Invited speakers: Jo Edgar (poultry) and Armelle Prunier (pigs)

Mini research seminar
≥Ute Knierim: A tool to work on risk factors during rearing for feather pecking in laying hens
≥Elske de Haas, Margrethe Brantsæter & Fernanda Machado Tahamtani: Disrupting availability of floor substrate in the first weeks of life influences feather pecking during rearing and lay – a Dutch and Norwegian approach
≥Anouschka Middelkoop: Effect of early feeding on the behavioural development of piglets around weaning
≥Irene Camerlink: The crooked mind of the commercial pig: can we rectify abnormal biting behaviour by early and later life conditions?

14:30-14:50 Coffee/tea break
14:50-15:50 Theme 2 continues: Group and plenary discussion, Sandra Edwards
15:50 Closing of workshop

Some tweets from the workshop:

Acute lethal aggression is increasingly seen in commercial pig farming, as is excessive neonatal aggression (Irene Camerlink)

About 50 studies link (in-)adequate foraging to injurious feather pecking in poultry (Jo Edgar).

Maternal care strongly influences chick behavioural development (Jo Edgar)

Study: Lots of ear biting on Irish pig farms, up to 50% of pigs; Follow up: Antibiotic use may play a role (both causing & treating) (Laura Boyle).

Feather pecking appears to be linked to keel bone damage (Anja Brinch Riber).

Feather pecking is associated with elevated specific immune response (Jerine van der Eijk).

Tipping bucket model of feather pecking
Tipping bucket model of feather pecking (modified after Bracke et al. 2012 model for tail biting).

Lasers to guard organic hens from bird flu

An organic egg farm in England has set up a novel method of protecting its hens from bird flu allowing them to stay outdoors.

Orchard Eggs based in West Sussex has taken advantage of the latest laser technology available from a Dutch company in order to scare off wild migratory birds and prevent them mixing with the farm’s chickens. As the British government recently extended the avian influenza (bird flu) prevention zone to April 2017, it also raised the biosecurity requirements poultry farmers must adhere to if they want to keep their birds outdoors. Orchard Eggs, owned by young Dutch couple Karen and Daniel Hoeberichts, said once they heard of the new laser technology steps were taken to set it up to complement the farm’s other biosecurity measures.

Read more. (Original article by Chris McCullough, 2017. Poultry Farm Sets Up Lasers to Guard its Organic Hens from Bird Flu – The Poultry Site).

Probiotics may help in dealing with feather pecking

Beak trimming is commonly used to reduce the incidence of feather pecking but this practice is more and more under discussion and banned in several EU countries. The side effects of non-trimmed beaks is an increased feed intake, as the birds have less plumage to keep them warm. Probiotics can be part of the solution.

Laying hens provided with Bacillus subtilis showed better performance (egg weight, egg mass & FCR) in the early stages of production, and persistent larger eggs over the whole period, without negative impact on feed conversion, hen weight and egg shell quality.

See full article by Pauline Rovers-Paap, Orffa Additives in Poultry World, Feb 20 here.

Health tool

Poultry World launched a poultry health tool. It is a rather general introductory entry to main poultry health issues. The tool was created with the assistance of Dr Joseph J. Giambrone, Professor at the Poultry Science Department, Auburn University, USA Maarten de Gussem, veterinary expert, DMV, VetWorks.

The tool lists 66 diseases, organized in four categories: Skin and skeleton, Nervous system, Digestive system and Respiratory system. Unfortunately, the category ‘Skin and skeleton’ is lacking an entry on feather pecking. For this, it is better to visit the Henhub site.