• The use of carcass measures to understand lifetime pig welfare status was explored.
• Tail and skin lesions acquired in early life remain visible on the carcass.
• These lesions were not necessarily visible on the live animal in later life.
• Carcass weight was negatively associated with persistent tail injuries.
• Therefore carcass lesions and weight provide useful lifetime welfare information.
There is increasing interest in developing abattoir-based measures of farm animal welfare. It is important to understand the extent to which these measures reflect lifetime welfare status. The study aim was to determine whether lesions acquired during different production stages remain visible on the carcass, and the degree to which carcass-based measures may reflect broader health and welfare issues. 532 animals were assessed at 7, 9 and 10 weeks of age (early life, EL), and at 15 and 20 weeks of age (later life, LL) for tail lesions (TL), skin lesions (SL) and a number of health issues (HI) including lameness and coughing. Pigs were categorised according to when individual welfare issues occurred in the production process; ‘early life’ [EL], ‘later life’ [LL], ‘whole life’ [WL], or ‘uninjured’ (U) if showing no signs of a specific welfare issue on-farm. Following slaughter, carcasses were scored for tail length, tail lesions, and skin lesions and cold carcass weights (CCW) were obtained. Generalised linear, ordinal logistic and binary logistic fixed model procedures were carried out to examine the ability of TL, SL and HI lifetime categories to predict carcass traits. Pigs with TL in EL, LL and WL had higher carcass tail lesion scores than U pigs (P < 0.001). Pigs with TL in LL (P < 0.05) and WL (P < 0.001), but not in EL (P > 0.05), also had shorter tails at slaughter than U pigs. In relation to TL scores, U pigs also had a higher cold carcass weight compared to LL and WL (P < 0.001), but not EL pigs (P > 0.05). Pigs with SL in EL, LL and WL had higher healed skin lesion scores on the carcass than U pigs (P < 0.001). Health issues recorded during lifetime were not reflected in carcass measures used (P > 0.05). The current study shows that tail lesions and skin lesions, acquired at least 10 weeks before slaughter, remain evident on the carcass and consequently, may be useful as tools to assist in determining the lifetime welfare status of pigs. Low CCW was associated with tail lesions, supporting previous research suggesting that tail lesions have a negative impact on growth performance in pigs.
Tail docking is an undesirable mutilation of pigs. Currently virtually all young piglets are docked in conventional farming so as to prevent tail biting later in life. However, throughout Europe efforts are made to reduce tail docking. Often farmers provide additional enrichment to try and prevent tail biting. Nevertheless, stopping the practice of tail docking may, and frequently does, lead to elevated levels of tail biting, resulting in tail wounds. In relation to this farmers and policy makers would like to know what levels of tail biting would be equivalent to tail docking in terms of pig welfare, i.e. how much tail biting can be allowed before deciding it would be better to continue tail docking. But this poses the problem how to weigh the (lack of) welfare involved in tail biting of a grower or finishing pig against the pain of tail docking of young piglets. Is this possible? And if so, how?
We recently had a brainstorm session on this subject. This is an outline of what we came up with, including a very tentative personal estimate (by MB).
In my personal view when (in the end up to) about 12% of undocked pigs were tail bitten that would be roughly equivalent in welfare to the docking of all piglets. The uncertainty margin, however, is high, at least ranging from 5-25%. The reasoning underlying my estimate is as follows.
Firstly, piglets are normally docked using hot iron cautery. This is quite painful as it involves applying both heat and rather blunt trauma. The heat kills bacteria and thus may reduce the chance of subsequent infection of the tail wound. Tail biting at a later age, by contrast, is caused by even more (and multiple) blunt trauma (due to biting). It also has a substantially higher likelihood of infection. In addition, there is e.g. fear in the tail bitten pig due to being chased by a biter. Based on this I would say that pain (and stress directly related to tail biting) may roughly be about ten times as high in intensity and about ten times as long in duration, compared to tail docking. This would imply that 1 tail-bitten pig is off-set by about 100 docked piglets as regards the intensity and duration of the pain involved.
However, animal welfare encompasses more than just pain. An important additional factor is the level of stress which is not directly related to tail biting activity.
Firstly, there may be stress related to the treatment of tail biting, e.g. when biters and/or victims are taken out of the pen (resulting in social isolation and/or fighting). This stressor, however, is partly offset by the enhanced enrichment normally provided to pigs experiencing an outbreak of tail biting (though not all pigs are equally affected by the ‘costs’ and ‘benefits’). Note that there is another, more macabre, offset involving ‘happiness’ too, and that is the excitement experienced by the (sometimes fanatic) biter pigs when a tail-biting outbreak has started. Note also, that this biter ‘welfare’ is at the same time an indicator of the level of (background) stress experienced by pigs leading to this abnormal behaviour in the first place.
A much more important source of stress that must be taken into account, therefore, is related to the general housing conditions to which the pigs are exposed prior to a tail biting outbreak. Tail biting is an unnatural behaviour that is triggered by (some kind of) stress. Pig farmers are aware of this and will try and prevent tail biting by generally improving the housing conditions when they (start to) raise pigs with intact (undocked) tails. Thus the expected level of stress to which the pigs are exposed is likely to be higher in the case of routine tail docking. When farmers stop tail docking they normally provide much better enrichment (rooting material & space). Farmers raising pigs with intact tails will also take other measures to reduce stress, e.g. provide better climatic conditions, better feed and better health care. These stress-reducing measures don’t just apply to the biters or the victims of tail biting. They apply to all pigs in the pen. Furthermore, they don’t just apply during an outbreak of tail biting, but they apply throughout the pigs’ lives. Hence, the reduced stress levels are a major factor reducing the off-set between docking and tail biting based exclusively on pain (and pain-related fear). I would estimate that the improved living conditions may reduce the off-set by at least a factor 10. This would mean that taking into account both pain and stress, 100(%) docked pigs (kept with minimal care and in a more barren environment) could be roughly equivalent to similarly-sized group of pigs with intact tails under enriched conditions and in which 10% of the pigs has been tail bitten.
Tail biting in docked pigs
However, we know that tail biting does not only occur in undocked pigs. It is also seen in docked pigs. Roughly 2% of docked pigs are tail bitten. It seems safe to assume that the level of pain from being tail bitten is roughly comparable in docked pigs and in undocked pigs (though docked tails may be more sensitive and thus less likely to get bitten). Taking this into account would imply that 100 docked pigs of which 2% also experiences tail biting later in life would be having a level of (poor) welfare comparable to 100 undocked pigs of which 12% gets tail bitten. This is about 6 times as much tail biting as the 2% base-line set under conventional docking conditions.
It must be emphasised again, however, that this level of 12% tail biting is a very rough estimate. So, a wide safety-margin applies, e.g. 5-25%. This may depend in particular on the quality of enrichment and the extra care provided under non-docking conditions.
Please note, that this post is the result of a brainstorm session only and presents a personal view. It illustrates how systematic reasoning (using principles of semantic modelling) can be used to start to answer this rather important welfare question. I have provided a very rough estimate. For a more accurate assessment more detailed studies would certainly be required, both in terms of more carefully including what is already known and in terms of accumulating more empirical knowledge about what is not known yet. At present the assessment is still very speculative, and meant to illustrate primarily how to in principle deal with the question of what level of tail biting is equivalent to a practice of routine tail docking.
Postscript: Excluded aspects and some feedback from readers
Note that, in my estimate I neglected several (minor) aspects.
Firstly, I neglected the fact that for tail docking piglets must be picked up. This results in stress, both in the mother sow and in the piglets. From an evolutionary perspective the procedure of catching piglets may be equivalent to experiencing capture by a predator. This would mean that the given estimate would be a moderate underestimation. However, tail docking may be performed in combination with other treatments such as iron injection and castration. If so, the additional stress from handling may be relatively minor. Note, however, that castration applies only to males and may be banned in the near future, and iron injection may be given orally as a kind of ingestible compost, or as has recently been shown, may not be necessary at all. Hence, combining such treatments with tail docking has a reducing likelihood.
Secondly, I assumed that teeth cutting will not be practiced to treat an outbreak of tail biting, neither in the docked pigs, nor in the undocked pigs. Or, more precisely, at least I assumed teeth cutting is not practiced in substantially different numbers of pig. Such teeth cutting is painful and illegal, so it could be considered appropriate to ignore the practice. However, if it were practiced more in undocked pigs (which are likely to experience higher levels of tail biting), then it would have a substantial impact on the level of equivalence, pushing the percentage back down again substantially.
A third point to note is that I did not include in the estimate other ethical considerations or our (anthropomorphic) emotional responses. An example of the latter may be related to the amount of blood seen in the pen, the farmer’s level of stress (unpredictability) associated to this, and the potentially adverse economic consequences associated with tail biting. An example of other ethical considerations is the fact that tail docking may be considered to be an infringement of the animals’ integrity or intrinsic value. In such a rights-based moral view tail docking may be considered ethically wrong, regardless of the level of tail biting when tail docking is stopped. Such aspects were excluded because these are aspects not directly related to animal welfare. They are more related to our human perception of ethics and/or human welfare, rather than animal welfare.
Finally, it is most important to emphasise that I have considered steady-state conditions, but realize that all practices are subject to optimisation. The practice of tail docking has already been optimised for over a period of at least 50 year. By contrast, the practice of raising pigs with intact tails still more or less has to enter the phase of optimisation in commercial practice. This implies that substantially higher levels of tail biting may be regarded as acceptable, provided this is only temporary and provided it leads to substantially lower levels of tail biting later on. In other words, it requires that farmers will persist in raising pigs with intact tails and have a chance to learn to deal with it over a certain transition period, both in terms of prevention and treatment of tail-biting outbreaks.
Feedback reader 1:
Regarding the painfulness of tail biting vs tail docking, I find it impossible to guess the relation – especially as tail biting comes in so many forms.
I absolutely agree that a weighing like this is necessary, but I also think it is a bit dangerous to throw out estimates that are not really based on any evidence (or at least you do not present any?), such as the 100 times worse pain experienced by bitten pigs than docked pigs. Also, tail biting is very heterogeneous, from just a small, one-time bite, to a chronic situation, where the entire tail is lost, so the way you estimate the pain simplifies the matter greatly.
As to the expected level of actual tail biting when docking is stopped: I estimate a two-fold increase in tail biting if no docking is performed. Perhaps somewhere between 2- and 4-fold, based on e.g. slaughterhouse data. There may be a 4-fold increase when the housing situation is not improved otherwise – which you also take into account in your text – when applying a non-docking policy the farmer would normally also improve housing conditions, thus reducing the risk further. I certainly agree that when a farm stops docking, they will probably have a higher incidence of tail biting initially, but on the long-term (as is shown e.g. in Finland where tail docking is totally forbidden, and the tail-biting incidence, based on abattoir data is around 2%), a 10 or 12% incidence is certainly higher than I would expect.
Feedback reader 2:
Having read your blog I think you need to factor in adaptive, compensatory pain modulation into your model.
It is sometimes too easy to fail to take into account post-injury peripheral and central modulation of pain signalling that occur as part of the normal healing process and only focus on the ‘pro-pain’ component.
I also don’t see how you can substantiate this claim?
‘Based on this I would say that the pain of tail biting may be about ten times as high and about ten times as long, compared to tail docking. This would imply that 1 tail-bitten pig is off-set by about 100 docked piglets as regards the intensity and duration of the pain involved’.
While I think it might be possible to attribute weighting to some risk factors within systems, I don’t think it can be applied to pain experienced by an individual (or even at group level as you are suggesting) because there are so many factors that contribute to an individual’s experience of pain? I don’t think you can quantify the painfulness of tail biting and tail docking.
Also when thinking about stress you might want to define what you mean by that in relation to chronicity?
Short-term compensatory responses to stress are in my view positive for the animal; however beyond that when there is a failure of compensation and ultimately homeostatic decompensation then they are undoubtedly negative.
I guess I’m suggesting that any weighting approach might need to accommodate (or factor in) changes over time (i.e. dynamic weighting?)
I hope you find my comments helpful?
As to substantiation, again, it’s my suggestion for a start of an argument to answer this in my view fairly important question. My answer is based on my personal experience as a vet and scientist, and on reasons indicated in the blog. It is certainly in need of further study, examination and assessment. I fully acknowledge the considerable level of uncertainty as well as the risk associated with trying to answer the question. At the same time, however, I would also argue that there is a considerable risk in refusing to try to answer the question, as this leaves the issue to stakeholders.
Feedback reader 3:
Joining the discussion rather late, but basically I agree with the points others have made. I think it quite reasonable to conceptually set out the trade-offs which would determine the level of tail biting above which tail docking could be ethically justified, but putting numbers on some of these things is rather difficult.
For risk of tail biting in docked and undocked pigs we have a growing number of published sources and comparative national data.
For experimental comparisons we have old data suggesting increases of 30-60% in pigs in unbedded systems.
More recently we have studies suggesting somewhat lower results if straw is given.
So this part is perhaps simple, but depends on your assumptions about which husbandry systems will pertain across Europe.
For the welfare detriment of tail docking and tail biting, data indicate that both have long lasting effects on pain processing pathways, but the implications of this for pain perception for the individual are uncertain.
For tail docking, the data I have seen are still contradictory on whether cautery is more or less painful than simple section (some suggest the cautery destroys the nerves whilst others suggest greater pain). There is also the possibility of tail docking with anaesthesia/analgesia as a route of adoption.
For tail biting, the short term pain will certainly depend on the severity and, even more, on the prevalence of infection. The data on this are currently lacking to my knowledge.
The welfare impairment of keeping in conditions which give rise to tail biting is clearly the greatest of all in magnitude (severity x duration x no of animals) but I don’t think we have any way of comparing the welfare severity of ‘behavioural frustration’ against that of injury/pain. I would be concerned about taking arbitrary figures in the absence of any logical basis.
So, I guess my suggestion would be to explore the framework for this decision, but be very wary about pretending we can quantify it.
I also think the issue not addressed in your blog is the time course of any transition to cessation of tail docking and how to manage this. What proportion of farmers would have the awareness, capital and staff training to implement the changes necessary to their existing housing if obliged to cease tail docking (some older, fully slatted and large group housing systems will pose much bigger challenges and possibly require replacement of buildings), and how long would it take across Europe to reach the ‘acceptable’ situation of relatively low differential in tail-biting prevalence between docked and intact tails, rather than the ‘unacceptable’ differential shown for “one off” change in tail-docking experiments (stopping docking without further improvement of the environmental conditions). I think it important to highlight that your analysis relates to a ‘steady state’ situation and the importance of how any transition is managed and the welfare implications which this will have.
Note that I have not been comparing docking versus non-docking in a mono-factorial way. I compared docking in a more barren environment versus not docking in a more enriched environment supplemented with special attention by the farmer, as that is what will normally happen in practice. I have now emphasised this more clearly in the text.
I largely agree that we currently largely lack the data needed to quantify more precisely. However, I also believe that in principle it is possible to do so, and that the estimate/assessment can be more or less verified empirically (as the body of knowledge accumulates and modelling principles are improved). Personally, I am inclined to try and quantify despite considerable uncertainty, because it provides a better starting point for further discussion. In addition, such preliminary but more science-based estimates are much needed to complement the inevitably politically-loaded figures and personal assessments presented by farmer-representatives and NGO’s arguing either (rather exclusively) against or in favour of ending tail docking as a routine practice to prevent tail biting.
An important point I’ve been trying to make is that pain is not the only relevant aspect of welfare involved in tail docking and tail biting, and that the levels of enrichment and care should also be taken into account. I don’t think it is even possible to honestly say it is not possible to ‘add’ these aspects, since proper political decision making (in all kinds of areas, not just tail biting) simply does and has to, whether it is considered scientifically possible or not. And if so, I would argue it is most reasonable to try and provide the best possible scientific support, while being as honest as possible e.g. about uncertainty margins and the relevance of incorporating more information. I also think the estimate provides broad support to ‘farewell-dock’ initiatives such as those in Finland, Sweden, Denmark, the Netherlands, the UK and Germany.
Please have a look at this pig’s tail. You may note that contrary to most EU pigs, this Finnish pig has a curly tail. In addition, please note that this pig does not only has a curly tail. Its tail also has a hairy plume. That is what a pig’s tail should look like: It is the pig’s welfare thermometer.
Curly tail as sign of melting pig-welfare iceberg
The FareWellDock project has accumulated scientific information directed at reducing the need for tail docking in Europe. In this way it has contributed to ending the progressive melting of the pig-welfare iceberg. But sometimes, a picture says more than a thousand words, for the pig’s tail is an iceberg indicator for pig welfare.
Tail biting is a common problem in growing–finishing pigs, which can compromise health, growth, and welfare of pigs. Because tail biting is an abnormal behavior performed by tail biters toward victimized pigs, understanding these pigs may help us solve the problem. This study was conducted to evaluate immune function of tail biters and victimized pigs. Pigs (n = 240; 25.7 ± 2.9 kg initial weight) were housed in 8 pens of 30 pigs for 16 wk. Once visible blood on a tail appeared, pigs in that pen were assessed daily for tail score (0 = no damage, 1 = healed lesions, 2 = visible blood without swelling, 3 = swelling and signs of infection, and 4 = partial or total loss of the tail). Victimized pigs were defined as pigs with tail scores equal to or greater than 2. Meanwhile, a 2-h observation was conducted for 2 consecutive days to identify tail biters. In each pen in which tail biting occurred, blood samples were collected from victimized pigs on the day that tail biting was first observed as well as from tail biters and 2 control pigs with no sign of tail damage. Fourteen biters (6 barrows and 8 gilts), 30 victimized pigs (21 barrows and 9 gilts), and 28 control pigs (14 barrows and 14 gilts) were identified for blood sampling. Total serum protein and IgG concentrations were analyzed using the spectrophotometric method. Data were analyzed using the Glimmix model of SAS (SAS Inst. Inc., Cary, NC). Compared with control and victimized pigs, tail biters had lower total serum protein (P = 0.01; Table 018) and IgG concentrations (P = 0.01), suggesting poor immunity. There were no differences in total serum protein or IgG concentrations between control and victimized pigs. These preliminary results suggest that tail biters may experience compromised immunity.
This study examined effects of the amount of straw offered on occurrence and severity of gastric lesions in pigs kept in pens (18 pigs, 0.7m(2)/pig) with partly slatted flooring and 10, 500 or 1000g straw/pig/day from 30kg live weight. The pigs had ad libitum access to dry feed. Forty-five pigs were used, three from each of 15 pens. After euthanisia, the dimension of the non-glandular region of the stomach was measured. Lesions were characterized and scored. Irrespective of straw provided, 67% of the pigs showed signs of gastric pathology. Pigs provided with 500 or 1000g straw were pooled as ‘permanent access’. The proportion of pigs with ulcerations was reduced by permanent access to straw (7 vs. 33%; P<0.05), suggesting that permanent access to straw may improve animal health, and be considered as one possible strategy to limit gastric ulceration in pigs.
We investigated the effect of straw amount on pigs’ time spent manipulating straw.
We investigated the effect of straw amount on pigs’ simultaneous straw manipulation.
Increasing straw from 10 to 430 g/pig/day increased both measures.
Increasing straw above approx. 250 g did not significantly increase the behaviour further.
According to European legislation, pigs must have permanent access to sufficient quantity of material to enable manipulation activities. However, few studies have quantified how much straw is needed to fulfil the requirements of growing pigs. We investigated the effect of increasing amount of straw on pigs’ manipulation of the straw, and hypothesised that after a certain point increasing straw amount will no longer increase oral manipulation further. From 30 to 80 kg live weight, pigs were housed in 90 groups of 18 pigs in pens (5.48 m × 2.48 m) with partly slatted concrete floor and daily provided with fresh uncut straw onto the solid part of the floor. Experimental treatments were 10, 80, 150, 220, 290, 360, 430 or 500 g straw per pig and day. At 40 and 80 kg live weight, the time spent in oral manipulation of the straw by three focal pigs per pen (large, medium and small sized) were recorded along with the percentage of pigs manipulating straw simultaneously. This was recorded in three 1-h intervals (1 h before and 1 h after straw allocation in the morning, as well as from 17 to 18 h in the afternoon). With increasing quantity of straw provided, we found a curvilinear (P < 0.01) increase in the time spent in oral manipulation of the straw. Smaller pigs spent more time manipulating straw than larger and medium sized pigs (367, 274 and 252 s/h for small, medium and large sized pigs, respectively; P < 0.001), and pigs spent more time manipulating straw at 40 kg than 80 kg live weight (356 vs. 250 s/h; P < 0.001). At both live weights, pigs spent most time manipulating straw during the hour after allocation of straw. Similar effects of increasing amounts of straw were found for the percentage of pigs engaged in simultaneous manipulation of the straw. Post hoc analyses were applied to estimate the point, after which additional straw did not increase manipulation of straw any further. For the time spent manipulating straw the estimated change point was 253 (approx. 95% confidence limits (CL) 148–358) g straw per pig and day. For the number of pigs simultaneously manipulating straw the change point was 248 (CL 191–304) g straw per pig and day. These results show that increasing the quantity of straw from minimal to approximately 250 g per pig and day increased the time spent in oral manipulation of the straw, as well as the occurrence of simultaneous straw manipulation.
Hence, data from the current experiment identified 250 g straw per pig per day as the amount of straw where a further increase in straw provision did not further increase neither time spent on oral manipulation of straw, nor the percentage of pigs simultaneously manipulating straw. This suggests that, within the current housing system and using this criterion, this amount of straw may be the biological turning point for increasing oral manipulation of straw.
Tear staining or chromodacryorrhea refers to a dark stain below the inner corner of the eye, caused by porphyrin-pigmented secretion from the Harderian gland. It has been shown to be a consistent indicator of stress in rats and to correlate with social stress and a barren environment in pigs. The current study was, to our knowledge, the first to test it on commercial pig farms as a potential welfare indicator. The study was carried out on three commercial farms in Finland, in connection to a larger study on the effects of different types of manipulable objects on tail and ear biting and other behavioural parameters. Farm A was a fattening farm, on which 768 growing-finishing pigs were studied in 73 pens. Farm B had a fattening unit, in which 656 growing-finishing pigs were studied in 44 pens, and a farrowing unit, in which 29 sows and their litters totalling 303 piglets were studied in 29 pens. Farm C was a piglet-producing farm, on which 167 breeder gilts were studied in 24 pens. Data collection included individual-level scoring of tear staining; scoring of tail and ear damage in the growing-finishing pigs and breeder gilts; a novel object test for the piglets; and a novel person test for the growing-finishing pigs on Farm B and the breeder gilts on Farm C. On Farm A, tear staining was found to correlate with tail damage scores (n=768, r s =0.14, P<0.001) and ear damage scores (n=768, r s =0.16, P<0.001). In the growing-finishing pigs on Farm B, tear staining of the left eye correlated with tail damage (n=656, r s =0.12, P<0.01) and that of the right eye correlated with ear damage (n=656, r s =0.10, P<0.01). On Farm A, tear-staining sores were lower in the treatment with three different types of manipulable objects as compared with controls (mean scores 3.3 and 3.9, respectively, n=31, F29=4.2, P<0.05). In the suckling piglets on Farm B, tear staining correlated with the latency to approach a novel object (n=29, r p =0.41, P<0.05). Although correlations with tail and ear damage were low, it was concluded that tear staining has promising potential as a new, additional welfare indicator for commercial pig farming. Further research is needed on the mechanisms of tear staining.
Oberst et al. (2015) presented a poster on the effect of tail docking in neonatal pigs on the expression of genes involved in modulating anxiety-like behaviour at the annual meeting of the Scandinavian Association for the Study of Pain (SASP) at the Karolinska Institute, Stockholm, Sweden (13-14th April 2015).
The abstract is presented below; the poster can be found here
Background: Adverse experiences in early life, such as exposure to stress, can have long term detrimental effects on the future physiology and behaviour of the animal. Typically animals exposed to such experiences are more anxious and more reactive to stress in later life. Tail biting is a major problem in modern pig production, both in terms of animal welfare and productivity. Tail docking in early postnatal life is common practice to reduce risk of this problem, but causes pain and may alter pain sensitivity.
Aims: To investigate whether a significant painful experience in early life (tail docking) alters the expression of genes in the amygdala that are linked to an anxiety-prone phenotype.
Methods: Eight female piglets (Landrace/Large White x synthetic sireline) were used. Four piglets were tail docked (amputation of approx. 2/3 of the tail) on post-natal day 3 using hot-iron cautery and four sham-docked piglets served as intact controls. On post-natal day 10, pigs were sedated and then euthanized by barbiturate overdose. Brains were removed, the amygdala grossly dissected and frozen on dry ice. 20μm sections were cut and subsequently processed using in situ hybridisation with radiolabelled probes complementary to corticotropin-releasing hormone receptor-1 (Crhr1) and CRH receptor-2 (Crhr2) mRNA.
Results: Crhr1 mRNA expression was significantly greater (p<0.05) in the amygdala of tail-docked piglets compared with the sham-docked animals. There was no significant difference detected in Crhr2 expression in the amygdala between the groups.
Conclusion: Increased expression of Crhr1 in the amygdala is associated with an anxiety-prone phenotype in rats and pigs, thus it is likely that tail docking in early life leads to enhanced anxiety which may have a negative impact on pig welfare. Ongoing experiments will determine whether these central changes in gene expression are long-lasting.
[Support: BBSRC, DEFRA-part of ANIWHA ERA-NET initiative].
Oberst, P., D.A Sandercock, P.Di Giminiani, S.A. Edwards, P.J. Brunton, 2015. The effect of tail docking in neonatal pigs on the central expression of genes involved in modulating anxiety-like behaviour. Abstract for the poster presentation at the Scandinavian Association for the Study of Pain (SASP) Annual Meeting, Karolinska Institute, Stockholm, Sweden. 13-14th April 2015.
With the increase in attention to animal welfare, researchers have focused their interest on the assessment of pain in farm animals. In humans who cannot self-report, such as infants and unconscious patients, the observation of facial expression is frequently used for pain assessment (Prkachin, 2009). The possibility to assess pain through changes of facial expression has also been studied in animals, and pain scales developed which include the ‘Mouse Grimace Scale’ (Langford et al., 2010), the ‘Rat Grimace Scale’ (Sotocinal et al., 2011) and the ‘Rabbit Grimace Scale’ (Keating et al., 2012). Although with some species differences, the three scales focus on the eyes, nose, cheeks, ears and whiskers of an animal.
Although pigs have fewer muscles for facial expression, there are subtle changes in appearance (Flecknell & Watermann-Pearson 2000), but there are currently no published pain scales based on facial expression in pigs. The aim of this research was to investigate if it is possible to observe changes in piglets’ facial expressions immediately after painful procedures. Thirty-one piglets were subjected to tail docking by cautery, while held by the farmer. Images of faces were taken immediately before and after this procedure. These images were sorted and those in which piglets had closed eyes were excluded.
Images were evaluated by two treatment-blind observers, scoring from 0 to 2 (0 was no evident tension and 2 very evident tension).
Because of the non normal distribution, data were analysed with the non-parametric Wilcoxon Signed Rank Test, which showed that the cheek tension score significantly increased from before to after the procedure (P<0.042). This result shows promise for the adoption facial expression as a tool for acute pain assessment in pigs.
In piglets subjected to tail docking cheek tension score significantly increased from before to after the procedure (P<0.05)
Tail docking is a common practice in most EU countries to reduce tail biting in pigs. Tail biting causes pigs pain and stress but, more importantly, it indicates underlying welfare problems. In a few European countries, such as in Finland, tail docking is forbidden by the national animal welfare act. Yet in Finland, pork production is a professional livelihood ranging from small to large piggeries where all pigs have tails. Animal welfare standards are slightly higher than average on a European scale and farmers take several welfare-improving measures to prevent tail biting. By addressing the problems in animals’ living conditions, health, nutrition and behaviour, tail docking is made unnecessary. Admittedly, occasional outbursts of tail-biting have to be tolerated and biters as well as bitten pigs will have to be treated accordingly to maintain the balance between individual and herd-level welfare.
Pig tails on a large scale
Lively little piggies are nosing each other and biting nylon ropes hanging from the ceiling. A bit calmer and fleshier growing pigs are rooting straw on the pen floor and tasting penmate’s tails and ears. A few pigs have bite marks on their tails, even one freshly bitten tail can be seen, but every pig has a tail of its own as a premise.
Timo Heikkilä, the owner of the piggery, has almost 30 years’ experience in pig production. At the moment his piggery feeds 20 employees, 3500 sows, 4000 fattening pigs and 1200 gilts. The piggery is one of the biggest in Finland and of reasonable size also in European scale.
According to Heikkilä, tail biting used to be a problem on his farm, too. A few years ago there was a tricky situation where slaughterhouses could not take enough pigs in, leaving the pens overcrowded. After the pig rush eased, biting has been only occasional. Heikkilä stresses the importance of good feeding in improving pig welfare and reducing tail biting: there has to be enough feed of good quality available for all pigs. Also the conditions inside the piggery have to match the pig’s needs: feeding trough has to be long enough to serve every pig at the same time, and draught and temperature inside the pen have to be under control. It is also important to even out the litters right after birth, but after weaning penmates should not be mixed anymore.
Tail biting occurs on Heikkilä’s farm, too, but most of the tails are intact.
There is no bedding but the straw rack and a hanging toy provide enrichment for growing pigs (8–30 kg). Floor is mainly concrete and partially slatted. Ventilation seems to work fine as the pens are relatively clean.
Straw for enrichment
Good quality straw is the basis for effectively preventing tail biting, says Heikkilä. It’s not always easy to find large amounts of good straw to buy, so Heikkilä harvests his own straw through summer and fall. Using straw requires dry litter system or, as in Heikkilä’s piggery, a special slurry system designed to stand moderate amounts of straw. Ventilation and air quality are usually associated with the functioning of the slurry system and managing them all properly is especially important for keeping up animal welfare.
Heikkilä uses straw as enrichment material, not as bedding. Every pen has a small rack full of straw for the pigs to pull out and chew. There is only a small handful of straw on each pen floor, but the pigs are eagerly nosing the two straws crossed and rushing around when extra straw is thrown to the pen.
Newspapers, tar and strict rules
Prevention of tail biting through improved animal welfare is the most important measure, but when biting occurs, other measures are needed. Whenever there is a bitten tail, Heikkilä says he throws generous amounts of paper or straw into the pen, puts some tar on the bitten tail, and if possible, takes the bitten pig into a separate pen for recovery.
In Finland pig health in general is exemplary and antibiotic use is restricted. On Heikkilä’s farm, illness protection is profound. After a trip to home country, foreign employees face 48 h quarantine before entering the piggery. Work clothes are changed after a thorough shower and a Finnish sauna. The color coding of clothes for different piggery units is as strict as it is in the animal hospital of the University of Helsinki. Health as a part of animal welfare and a way to prevent tail biting is not a joke in this piggery.
If keeping pigs with tails in commercial, large-scale system works in Finland, why wouldn’t it work also in other European countries, Heikkilä suggests. He lists research, change of generations, shutdown of old-fashioned farms, and change in farmer and public attitudes as the most efficient ways of moving forward in animal welfare. All this requires also political goodwill and steering. The measures taken to improve pig welfare on Heikkilä’s farm don’t fundamentally differ from the basic Finnish standard, and there is a number of issues and options to further improve pig welfare. However, the reasonable scale and profitability of Heikkilä’s farm proves that these measures are feasible in modern pig industry.
Heikkilä cherishes the idea that every civilized state can afford keeping pigs with tails, and that we shouldn’t push animals too far but be happy with less to keep our animals happy as well. Tail biting may not ever completely end, but at least there would be less suffering if few animals are bitten compared with the situation where all animals have to face mutilation.
Heikkilä’s advice to keeping pigs with tails:
1. Wellbeing is the starting point. Avoid tail biting by prevention.
2. Provide enough room for feeding (pen size, trough length)
– all pigs have to have access to food simultaneously.
3. Take care of warm and draught-free resting area.
4. Take care of proper ventilation and air quality.
5. Give stimulation and rooting material preventatively, before problems arise.
6. Take good care of animal health.
“There’s always someone in charge of what is happening with the pigs – if it’s not me, it’s one of my employees”, says Timo Heikkilä.
Reseach related to prevention of tail biting:
FareWellDock is a three-year research project which is part of the Animal Health and Welfare (ANIHWA) ERA-net initiative. The aim of the FareWellDock project is to supply necessary information for quantitative risk assessment and stimulate the development towards a non-docking policy in the EU.
Read also the results of the Finnish research project on pig enrichment.