Tag: Model

Towards a common conceptual framework and illustrative model for feather pecking in poultry and tail biting in pigs – 3. Overview

This is post 3 on “Overview of main similarities and differences between feather pecking and tail biting” 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.

3. Overview of main similarities and differences between feather pecking and tail biting

Table 1 shows an overview of similarities and differences between feather pecking (fp) in poultry (i.c. laying hens) and tail biting (tb) in pigs (i.c. weaned and growing/fattening pigs).

Table 1 is based primarily on Brunberg et al. (2016) and supplemented with our own (esp. MB and TvN) knowledge about fp and tb (also as presented on the henhub website www.henhub.eu). The table is intended to summarise the most relevant similarities and differences between fp (in hens) and tb (in pigs), and thus support decision making in dealing with fp/tb in practice.

The key risk in fp/tb is the fact that both laying hens and pigs are originally omnivorous generalists that have been become production specialists in feed intake and food conversion in intensive farming conditions. The motivation for fp/tb relates to a frustrated foraging need, which is modulated by a whole array of different risk factors, hence resulting in this multifactorial welfare issue. In addition to similarities the table also identifies a number of differences between fp in layers and tb in pigs, e.g. we don’t have genetically selected lines for tail biting comparable to the high and low fp lines in poultry. Hence, an experimental model to study tb in more detail is currently largely lacking (though pigs selected for social breeding value (high indirect genetic effects for growth) showed considerably less ear biting, tail damage, aggression and enrichment manipulation (Camerlink et al., 2015), and may thus in principle be suited to be used to study tb experimentally in more detail).

The table may perhaps be improved upon further by specifying relationships between the items specified as risk factors (in the left column) and the different responses identified in the process of fp/tb (in the right column; cf (Fraser, 1987a)).

Another suggestion relates to the many risk factors that may hamper practical problem solving. While scientific experiments necessarily vary only a few risk factors in order to reliably examine which factors may affect fp/tb, a tentative suggestion for solving the multifactorial fp/tb problem could be to try to formulate multifactorial solutions. This may be esp. relevant when monofactorial solutions fail to solve the problem. However, an important drawback of this approach is that it may essentially remain unclear which factors are accountable for any (positive or negative) results. When a multifactorial approach is working, it may be possible to tease out in subsequent research the relative contribution of the different risk factors. When it doesn’t work, that may be the end of the road for that particular type of farming (given the constraints imposed).

Table 1. Comparing risk factors and animal responses related to feather pecking (fp) in poultry (laying hens) and tail biting (tb) in pigs, taking Brunberg et al. (2016) as a starting point, supplemented with own author expertise (marked as *). Common risk factors (similar across species, specified between brackets when ‘unknown’) are followed by notable differences between Hens and Pigs (specified on the next lines). Black characters: risk increasing factors; green: risk decreasing factors (benefits); red (in the column ‘risk factors’): particularly welfare-reducing risk factors. ‘No’: means that the opposite reduced fp/tb.; behav.: behaviour; envir.: environment; decr.: decreased; incr.: increased; HFP: high fp line/breed; LFP: low fp line; TIM: tail-in-mouth; w: weeks; d: days; mo: months. The cells in column ‘Responses’ are not directly (horizontally) related to the risk factors. Responses are stacked: more positive behaviours are presented at the bottom; worst (form of escalation, i.e. cannibalism) is shown on top. Responses are related to ‘type of animal’ (victim, actor, neutral) (with welfare aspects specified at the level of the type-of-animal label). Poor welfare responses are shown in red (in the column ‘responses’). See the text for a more detailed description of how to read the table.

Type of factor Risk factors (Multifactorial, related to the type of factor, i.e. environment-, group- & animal based) Responses (behav., physiology, pathology & welfare, related to type of animal, i.e. victim, actor, neutral) Type of animal
Envir.-based Modern large-scale specialised farms Victim: fear, pain (during outbreak), stress, sickness (during treatment, recovery) Victim
Barren pen (no proper foraging material, straw), large discrepancy between intensive farming envir. and the natural envir./envir. of evolutionary adaptation Cannibalism
(Partly) slatted floor
Hens: (Litter)
Pigs: Concrete		 (Wound) infection
Indoors*
Hens: Range (may provide foraging opportunities and reduce stocking density)
Pigs: – (Outdoor area may provide rooting substrate (soil), fibre (pasture), but not necessarily)		 Production loss (reduced growth)
Hens: Egg laying (reproduction)
Pigs: Growth (production)
One size fits all (food, climate*)
Standardised feed, optimised for average individual (vs indiv. needs); perhaps probiotics may treat fp/tb
Hens: –
Pigs: No phase feeding; decr. feeding frequency predicted tb outbreaks 9 w later; tb victims made more feeder visits 2-5w prior to tb		 Appearance
Hens: Deteriorating feather cover
Pigs: Tucked tails
Feed changes and ‘hiccups‘ in providing feed (unpredictable frustration) Decreased tryptophan, serotonin levels
Feed type; Reduced feeding time, not ground, concentrated feed, less fibre
Hens: Pellets give more fp than fine ground feed; no mash/pecking materials; high E diet; no feathers in diet (acting as fibre, incr. feed passage)
Pigs: Contradictory results (liquid/pellets/meal) but straw reduces tb & is consumed		 (Fp/tb) Wound(s)
Hens: Esp. tail, body (not back of head)
Pigs: Tail (possibly ears, flanks, legs)
Protein, mineral (NaCl) deficiency; supra-nutritional NaCl may alleviate fp/tb
Hens: Deficiency of crude protein, amino acids, minerals (Na, Ca)
Pigs: Nutritional imbalance incr. tb
Feeder space, feed competition (bite/peck to get access to feed) Salivation (pH incr.; alleviate peptic ulcers)
Rearing conditions (both poor rearing conditions and a backdrop from enriched rearing conditions to deprived conditions later in life)
Hens: Absence of litter around 5w, high stocking densities, rearing on wire floor
Pigs: More piglets/stockperson, fostering, no straw in farrowing pen, reduced feeder space during rearing gives more tb later in life; multi-litter rearing decr. manipulative behav.; providing straw during rearing and then depriving pigs of straw later is also considered a risk factor		 [Microbiota composition?] Hens: HFP has different microbiota composition than LFP; feather eating changes gut microbiota;
Pigs: Unknown
(Pen size, pen design)
Hens: (Large)
Pigs: (Small)		 Escalation of tp/tb (outbreak)
Group-based (envir.- & animal based) Group housing
Hens: (Very) large groups (10-100.000 birds)
Pigs: Small (~10 pigs)		 Arousal, restlessness, excitement (positive), fear & avoidance (negative).
Hens: Cut feathers increased fp
Pigs: Blood tail model (rope) increased (tail) biting behav.
High stocking density
Hens: More fp in largest groups (15-120 birds)
Pigs: (Not uniform results)		 Cognition, (social) learning, (synchronisation; copy-behaviour; stimulus enhancement)
Farm health status (any (major) stressor/immune suppressor probably)
Hens: Vaccination (specific immune stimulation) when young may incr. fp as adults; LFP have better immunocompetence; e.g. E. Coli incr. severe fp
Pigs: Better health status reduces tb; straw reduces infections		 Prevalence/intensity:
Hens: Fp on 86% of UK flocks; SFP esp. when adult; fp up to 135 bouts/bird/hr; 3 severe pecks/min
Pigs: Tb on 30-70% of farms; fanatic biters bite 11-25% of time
Mutilation (3 aspects are relevant: 1. Method used; 2. Amount of tissue removed; 3. Age of treatment; esp. 2nd aspects is relevant as risk factor)

Hens: Beak treatment (previous beak trimming (may remove larger/smaller part of the beak), now infrared beak treatment) (Note: In poultry, as it were the (future) actor is mutilated)

 Severe fp (SEP)/tb

Hens: –

Pigs: Three types of (severe/injurious) tb: two-stage (starting with TIM), sudden forceful, and obsessive (fanatic)
Pigs: Tail docking (longer or shorter part of the tail) (Note: in pigs as it were the (future) receiver is mutilated by removing the tail) Actor: (Excitement, pleasure [during outbreak], pain, stress [during treatment])
Hens: Pecker
Pigs: Biter		 Actor, performer
History of fp/tb (once an outbreak has occurred, the likelihood of another outbreak increases; animals are never the same again after an outbreak; (irreversibly) changed set points) Object-direction:
Hens: Towards feathers
Pigs: Towards the tail
Animal-based (Bred for) very high production-efficiency (genetics, breeds) (esp. genetic motivation of feed-related behav.; behavioural need to species-specific foraging behav); fp/tb has moderate heritability (~0.2) Neutral (in same pen)/control (on other pen):
Neutral as a biter in spe: boredom, frustration, behavioural deprivation, esp. of foraging motivation		 Neutral / control
Hens: (Eggs)
Pigs: Lean meat; neutrals have different genetics		 Gentle manipulation
Hens: Gentle fp is prevalent in young birds, decr. with age
Pigs: Tail in mouth (TIM),
Domesticated 5-6000 years ago; bred in 50 years of intensive selection from foraging generalists (omnivorous (variable diet; need to explore)) to meat & egg producing specialists; fp/tb not selected against; tb&fp are correlated to production, but not in the same way Pen-mate directed exploration
Hens: (Deteriorated) plumage condition
Pigs: Wet tails
Hens: Male peckers had higher body fat; female peckers had earlier onset of lay; HFP: Better growth, lower total egg mass, decr. feed efficiency
Pigs: Lower backfat, lean tissue growth		 Consummatory behav.:
Hens: Feather eating (more in HFP)
Pigs: –
Being different
Hens: Plumage colour (standing out from others; incidental pigmented birds were more often victims)
Pigs: [Lame pigs get bitten]		 Object/substrate-directed exploration/foraging in accordance with nature, showing natural behav. (50-60% of time)
Hens: Scratching, pecking
Pigs: Rooting, biting
Personality
Hens: Peckers appear more proactive, fearful (in open field), stress (cortisol shows variable results); more foraging & walking when young incr. fp as adults; HFP more active; mobility to get to the nestboxes (i.e. too calm birds are at risk for fp)
Pigs: Low backtest responders showed less pen-mate manipulation; biters more sitting & kneeling 6d prior to tb; victims more posture changes 6 d prior to tb; tail posture (tucked) may predict tb 2-3d before outbreak
Sex, probably females more active performers
Hens: All females
Pigs: Mixed/uni-sex; males receive more tb; uncastrated males are more likely to become fanatic biters (1 study)
Age: Onset around sexual maturity (also then shifting nutritional needs)
Hens: Adult (16-80wks); progesterone (& oestrogen) incr. up to 18w incr. fp; testosterone decr. fp; SFP ~20w in females, but not males
Pigs: Young, prepubertal (<5-6mo); perhaps associated with teething*
Body weight
Hens: –
Pigs: Biters are lighter; victims tend to be heavier before tb (later decr. growth)

Reading guide

This was blog post nr. 3 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 – 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 – 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

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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.

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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.

Acknowledgements

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