Methods of auditing pig wellbeing/welfare


Dr John Carr



The pig industry worldwide is progressively embracing methods to enhance pig welfare.  The method generally chosen has been using audits and checklists.  These ‘audits’ range from relatively a simple checklist with few questions (Malton Code UK 1990’s) to comprehensive assessments with scoring of farm systems with detailed booklets on compliance – SWAP programme (USA 2004).


The veterinary profession has been instrumental in many of these programmes and is generally regarded as being a key fair and impartial ‘auditor’ by all parties – from the farmer, slaughterhouse and pork consumer.  However, is the veterinarian really able to see the farm from the pig’s perspective?


The basis of most ‘audit’ systems relies on a checklist on the farm equipment and its interaction with the pigs in the building.  The primary assumption is that if the building facilities do not injure the pig – then the pig’s welfare is being adequately catered.  However, while this method is a good basis for a clinical examination of a farm it is not a good indicator of a pig’s welfare.


To audit the pig’s welfare, the assessor needs to understand the pig and their needs – which is fundamentally different from the farm and its needs.  The welfare audit demands an understanding of animal husbandry – a subject which is generally lacking depth in modern veterinary curriculums.


The basis of animal welfare is the 5 freedoms based on the Bramble code instigated in the 1960’s:

  1. Freedom from thirst, hunger and malnutrition
  2. Freedom from discomfort
  3. Freedom from pain, injury and disease
  4. Freedom to express normal behaviour
  5. Freedom from fear and distress

Farming inherently abhors any farm which fails to provide freedoms 1,2,3 and 5.  However, freedom to express its normal repertoire of behaviours can only be achieved if those behaviours are understood by the stockpeople and the veterinarian assessor.  Achieving normal behaviours should be the focus of an animal welfare “audit”.


To provide an environment suitable for pig’s its daily behaviour can be considered in eight broad categories:

Play; social interaction with other pigs; feeding behaviour; reproductive behaviour; behaviour at rest;  its defecation behaviour; the pig’s ability to adapt to inadequate environments and finally its interaction with man.


Each of these areas will be examined with examples from various parts of the farm.


Who are pigs?


Before we investigate behaviour we should introduce the central customer - the pig.


The suborder suina includes a range of species spread around the whole world represented by the Peccary (3 species) in North and South America; in Africa the hippopotamus (2 species) and the suidae: Warthog (2 species), Red River Hog (2 species) and Giant Forest Hog and finally in Euroasia: the Babirusa and suis (7 species – including Sus scrofa).


All modern farmed pig belongs to the species Sus scrofa. 


The pig is not naturally represented in Australia and Antartica.  Since European colonization of Australia, the pigs have successfully colonized the continent with over 20 million pigs now living feral.


The major limiting factor to the spread of the pig around the world is the snow line.  The pig otherwise has adapted to temperate and tropical forests, open savanna and desert areas.


Sus scrofa (the European Wild Boar) evolved in the dense temperate forests of Europe with a temperature range of 0-20°C.   The pig lives in the dense low light intensity forest of 50-200 lux and generally live close to water.  Pigs enjoy wallowing particularly in the hot weather.  The pig is polyoestrus but does exhibit some seasonal breeding.


Knowing the pig’s evolved environment is the basis for providing a suitable framework within which to farm.


Pigs at Play


Any stockperson watching a group of pigs will soon be amused to observe their play activities.  Play prepares them for situations and trains survival skills.


Pigs are extremely intelligent animals with a degree of complex behaviours that match and if not surpass a domestic dog.   Unlike cattle and sheep, pigs exhibit a greater inquisitive and individualist behaviour patterns.  This can be practically demonstrated when moving a group of pigs.  In many ways pigs are more like people than they would wish to admit.


Providing an environment where pigs can explore their play behaviour can help relieve stress and allow the pig to cope better if their environment is temporarily adverse.



Pigs will gain comfort and support from other pigs and/or other animals.  Pigs should not be kept in isolation.  There may be obvious exceptions when the pig is under treatment for meningitis or a severe lameness.  However, once the pig is over the critical stage of the condition it should be housed with other pigs of a similar weight and age.


Environmental enrichment

Adult pigs

Adult pigs, similar to adult humans generally have a lower requirement to play with items placed in their pen.  However, playing music to adult sows can have a calming effect and has been used to reduce savaging of piglets by gilts.   Farrowing sows can be provided with chopped paper, straw and hay to allow them to act out their nesting behavioural requirements.  Adult sows can be provided with some chopped straw even while being housed in stall accommodation.  Note that the bedding materials can cause disturbance to the slurry system which if blocked would lead to significant other problems.

Wean to finish pigs

All wean to finish pigs should be provided with toys within the pen.

The simplest toys are often the most effective.   Pigs love to play with chains, rattles, large plastic bottles, rubber belting, old boots and feedbags.  Large balls became popular in the 1990’s and while these can be useful, pigs can also become bored with them.  In addition they can be placed in feeders and block feed access.   Car tires should be avoided as they have metal supports which can be swallowed resulting in intestinal rupture.


Pen layout

Pen layout can encourage play behaviour.  However, note that in pens which are long and narrow this can result in a running game with large numbers of pigs running at high speeds.  As the pigs attempt to turn at the end of the pens, individuals may slip and become injured – including long bone fractures.  When designing the pen ensure that this running behaviour is catered for by providing chicanes which will slow the pigs down.


Social behaviour


Pigs are extremely social animals.  Their family group is matricidal based on a small family group of breeding females with their piglets and weaners.  The boars are solitary.  Sus scrofa live in groups of 20-40 individuals.  In modern farming we expect pigs to adapt to larger grouping.  The wrong group size can lead to excessive fighting and evidence of vice.   The major grouping time occurs at weaning.  Groups should be formed at weaning from which new animals will not be added.  The group can be subdivided as the animals grow towards finishing and are moved to new housing.  However, mixing and creating a new group will reduce growth rates by a week.  Wean to finish operations avoid this need to moving and potentially mix groups of pigs.


Weaning can be an extremely stressful time for the pig where we see a change in behaviour from a group litter to more individualistic within a new group of pigs.  This change is not immediately at weaning but takes a number of days.  It is therefore, imperative that the veterinarian assists this transition time.  However, the veterinarian needs to first understand the basic challenges of weaning.


What is the pig’s pre-weaning environment


It is important to try and mimic the pig’s pre-weaning environment in the immediate post-weaning period.  


Pre-weaning each piglet has:


A drinker each.

A feeder each.

Minimal competition at eating/drinking.

Eat and drink warm liquid feed.

Eat and drink as a group/litter.

Eat and drink once every 1-2 hours.  Sows in crates lactate once every hour.  Loose housed sows by 24 days lactate once every 2 hours.

Mother determines the time to eat – the piglet does not.  It is not an instinctive drinker, it is behaviour driven.

Sleep as a group.

Clearly defined sleeping area.

Clearly defined defecation area.


Piglet asleep

The piglet may not even recognise itself as an individual, only recognise the group


Environment immediately post-weaning

How many of these environmental features are catered for after weaning?  In addition, note that the pig would normally be weaned over a 12 week lactation period rather than the 3-4 weeks currently practiced in farmed pigs.


Water supply

It is essential to train the newly weaned pigs where their water supply is positioned.

The water supply needs to provide more than 500 mls/min.  Less than this flow, pigs will not spend enough time to get their daily water supply.  In the first week post-weaning there is little diurnal variation in water intake – unlike after a week where water consumption becomes associated with feed.  Insufficient water supply leads to fighting and ultimately variation in the group.  Consider adding a sweetener or citric acid to the water if it encourages intake.                                                                                             



Assess whether the pigs are comfortable by looking at the pigs when they are asleep and look where and how they are laying see lying behaviour discussed later.  It is essential to provide a sleeping area which is draught free and with an initial air temperature of 30oC.  Avoid gases moving from the slurry pits into the pig’s building.  Enter pens quietly to assess weaner lying patterns.  Noisy stockpeople will miss clear evidence of draughts  The provisions of windows looking into the nursery can greatly help the stockperson monitor the wellbeing of the pig’s under their care.  Keep the lights with 50-100 lux lit for the first 3 days so the pigs can find the equipment, before weaning they probably had 24 hours of light.



The floor needs to be non abrasive.  Having steps to feeders can cause damage to the knees and legs, particularly important in future breeding stock.  The stocking rate is important and you need to avoid both under- and over-stocking.  This can only be achieved through good pig flow.  Pigs to 20 kg require 0.2 m2; to 30 kg they require 0.3 m2.  All-in/all-out and adequate pressure washing/disinfecting is essential to prevent cross over of infection from one group to the next.


Stock the pig’s themselves

To manage the pigs adequately it is essential to maximise the weaning weight.  Provide alternative systems designed to provide more ideal environments to assist the smaller weaned pigs.  One possibility is by streaming.  These smaller more compromised pigs should be provided with wet creep feed for longer than the rest of the group.  Never introduce compromised pigs back into newly weaned pigs at 7 kg, the immune system of the 7 kg pigs is grossly inadequate to cope and never move weaned pigs back into the farrowing area.



Feed behaviour in the 1st five days impacts social interactions.

Palatability           Feed at this stage is a high quality, high cost milk diet.  The feed will sour quickly.  It is essential not to store the feed at above 18oC.  Ensure the feed bag is closed at all times.      

How many times to feed       Prior to weaning pigs eat every 1-2 hours (12-24 times a day) depending on the management system.  The mother determines feed times, the piglet does not.  Manually feed weaned pigs 6-4x a day with the stockperson acting as ‘mum’.   This is continued for 3 to 4 days post-weaning.  Ensure all weaners eat.   While this seems extreme, if the feed intake in the first week can be optimised this can be worth 10 days to finish and the reduction in treatments easily compensates for the extra labour effort.

Type of feed         The piglet thrives on liquid/porridge type feed.  Provide a creep/water mix.  Aim to get the pigs to ‘beg’ for the feed, this makes identification of any poor feed intake pig much easier, but does require a feeding system where all pigs can eat together.  Any weaner that misses two eating episodes should be taken to the trough and force fed/watered.

Type of feeder     It is vitally important in the first week that all pigs can eat together and therefore a trough is required.  The neck space for a pig at 7-10 kg is 70-100 mm.  The use of long feed troughs can provide sufficient space.  Once the pigs are eating well move to dry feeding through the normal pen trough.


Feeding behaviour

Feeding is an important event in the pig’s life.  For example in the last section it was discussed how feeding can impact social interactions.  Understanding the behavioural characteristics of feeding is vital for the stockperson to understand and observe.  A change in a pig’s feeding behaviour can be an important key to indicate poor wellbeing and therefore, the need for enhanced stockmanship.  The use of remote sensors in monitoring feed auger turns or feed bin weight changes can provide essential real-time information on pig health and wellbeing.


The classic feeding behaviour repertoire is demonstrated by nursing pig and the following outline illustrates the typical pattern exhibited by mother and her piglets.


Nursing Patterns

What attracts new born piglets?


Vocalisation of sows. Dark areas. Afterbirth and birth fluids. Movement along hair patterns.

Suckling after birth


Piglets contact the udder as quickly as 3 minutes, but average 15 minutes and 30 minutes to contact the teat


Milk is continuously available for several hours post-farrowing and there is little aggression as pigs sample multiple teats


Cyclic milk ejection, approximately hourly, results in more aggression until the piglets select their preferred teat.

Cyclic nursing and suckling (approximately once every hour)


Sow’s behaviour

Piglet’s behaviour

Slow grunting

Assemble at udder

Increase grunt rate

Nosing and teat location

Rapid increase in grunt rate

Slow suckling

Milk flow (15 sec)

Rapid suckling

Grunting declines

Slow suckling or nosing

Sleep or change position

Fall sleep

Teat Order


Established within 3 days


Consistence often over 90%


Less stable in large litters


About 10% of piglets use more than one teat


Multiple teats more common in small litters


Unused teats regress


When sow turns over, so does the piglet teat order, it is teat specific


Consequences of a teat order


Stable teat orders lead to more uniform growth


Relative weight gain within litters depends on competition for teats


Evening out litters by weights (first  3 days) or selective teeth clipping reduces small piglets


Unused teats produce less milk in subsequent lactation


Mixing after day 9 piglets find it difficult to re-make teat order.  It may take 2 days to restore order.  Thus the group weaning weight is reduced.

In with natural state  a sow would introduce her piglets to other sow's piglets around day 10.  After day 14 the group of piglets join the main group.

Poor housing before and after farrowing can significantly interfere with this nursing behaviour resulting in poor colostrum intake.  This can be disastrous for piglet survival.  If poor feed intake is chronic, reduce an individual pig’s access to milk resulting in reduced and variable weaning weights.  Facial necrosis may be seen in the affected piglets.  Understanding nursing behaviour and providing suitable environments minimize fighting during suckling.  If the piglet is provided with adequate milk supply it would not be necessary to teeth clip piglets within the first week of life.  This is demonstrated by outdoor farrowed pigs.


Reproductive behaviours


Providing an environment sympathetic to the pig’s reproduction needs is essential to the maintenance of pig flow and production.  Even pig flow is a key component to reducing variation within batches – eliminating overstocking and understocking a major cause of poor pig health and wellbeing.


The behaviours exhibited at courtship are used as an example.


Courtship sequence in pigs





























Methods to enhance the signs of oestrus in sows and gilts


Have the assistance of a boar, preferably a mature boar that is producing a large amount of pheromones (scents) that stimulate the female.  He must be trained in the layout of the dry sow house/gestation area, but must not become too accustomed to the work, or he will only detect the sows which waste their feed.

House sows and gilts no closer than 10 metre from the boars.  Ideally the sow and gilts should not be able to see the boars until the time to mate/detect oestrus.

Oestrus detection should start three days after weaning and continue daily until served and daily for the entire duration of pregnancy.

The boar should be presented to the head of the sow or gilt.  However, note that this is only stage one of the courtship sequence.

It is essential to have at least 20 minutes a day boar exposure in gilts to induce oestrus.  Constant exposure can be detrimental to the length of oestrus exhibited.

The boar needs to be within 1 metre of the sow/gilt face to stimulate oestrus.  The stimulatory pheromones are in the boar’s saliva.

Signs of oestrus should be exhibited within 30 seconds of boar contract.

Heat detection is easier if sows and gilts do not have boar stimuli (sight, sound or smell) for one hour prior to checking for oestrus.   Gilts only exhibit intense oestrus signs for periods of 7-10 minutes and may take 45 minutes before being able to re-exhibit oestrus.

Use another unfamiliar boar if sows or gilts exhibit some of the signs of oestrus, but will not mate.  This is particularly important in a group of gilts where one is detected by one boar but several others in oestrus are missed by the stockperson’s enthusiasm for the sow/gilt which exhibit’s first.

Apply all the principles of stockmanship

Ears to detect a calling sow

Eyes to detect the restless, nervous sow, which is off her food, has a swollen vulva, which is slightly red.

Touch to exhibit back pressure test in the presence of the boar

The commonsense to be quietly patient in observing animals.


Using this understanding of courtship behaviour allows for efficient effective breeding systems to be designed.  These systems can both speed up breeding programmes - reducing stockpeople boredom while maintaining or even increasing farrowing rates and litter size.


Behaviour at rest


To provide an environment which will help maintain the wellbeing of pigs in a group, it is essential that all members of the health team recognized the signs of comfort.  The behaviour of the pig at rest can be a useful real time indicator of comfort.



Lying pattern as a real time indicator of comfort

Too cold


A cold pig lies on the floor with their legs tucked under their body to reduce floor contact.  Lie huddles with other pigs.  Lie close to a wall

Pigs may shiver,  The pigs may become hairy

With larger pigs they seen unable to adopt this tucked position for very long and tend to lie semi-recumbent with their legs tucked into their body.


Within a group of pigs there will be a selection of lying patterns. The main group of pigs will sleep together in a pile, however, other pigs will be lying spread out but with maximum contact with the floor. These separated pigs will be the more dominant pigs. The lower order pigs will lie on the edge of the main group. Comfortable pigs sleep with legs stretched out from the body.  A hot pig may chose to lie in a wallow to make itself comfortable    Outdoor sow wallowing

Too hot

Pigs will be panting > 40 per minute

Pigs are generally dirty.

Lie away from other pigs, sometimes against a cold wall.

They do not pile

Lie in any wet/cooler area

Pigs will dig into earth/bedded floors.

The stockperson needs to understand the effect of adverse environments on the thermal-comfort requirements.


Environmental conditions which may change the thermoneutral zone of pigs


Change C

Straw bedding


Deep straw


Slight draught




Very cold and draughty


Pig housed on its own


Wet floor


Wet bedding


Fully slatted floor




Poor lying area


Restrict feeding



Note that in general it is more difficult to provide a cooled environment for pigs.  Cold pigs can be relatively easily warmed.  Stockpeople will often run buildings to make themselves comfortable rather than their pigs.  This is particularly seen in farrowing houses where the environment is complex – the mother (sow/gilt) requires an air temperature of 16-18°C whereas the offspring require 28-32°C ambient air temperature.  Note the lying behaviour of the mother and offspring allows the stockperson to maintain the wellbeing of both groups.


Defecation behaviour


Pigs are inherently clean animals and avoid lying in feaces.  From a few days of age pigs will become toilet trained to defecation in a specific area of the environment.


Pig’s defection area can be expected to be either:

Where the pen is coolest

Where the pen has a draught

Where the pen is wettest

Where the pen is darkest

Where the pen is most private


Floor defecation pattern

The defecation pattern of the pen provides a good long term indicator of comfort.  The veterinarian can see the area even without the pig’s presence.   Abnormal defecation patterns indicate a chronic reduction in optimal environment.


Hot pigs will specifically choose to wallow in feaces and slurry to assist cooling.  Sometimes, this is unavoidable, but its occurrence should be minimised.  Once pigs become ‘dirty’ they can be extremely difficult to retrain – even when provided with ‘ideal’ environments.


Abnormal defecation patterns can also limit other pen resources creating additional stressors – for example when pigs defecate into feeders, waters or over lying areas.


Adaptation to inadequate environments


The pig is able to accommodate a range of environments and cope with temporarily inadequate environments.  Big pen and large group situations allow the pig to choose the most suitable environment.  In particular the pig will select the best area to sleep and defecate.  However, a suitable sized area needs to be available for the pigs to find.


The pig demonstrates a predictable range of behaviours.  All members of the health team should be aware of the visual signs of vice and be willing to immediately investigate and change the environment.


When there are any evidence of vice the stockperson should immediately check the following stressors:

Check stocking density. Check tail length, in particular variability. Check feed particle size (target> 500 µm). Check salt (NaCl) concentration in feed or water. Check water supplies. Check for evidence of a draught at pig height (cold draught air speed > 0.2 m/sec). Check air quality  (target  - NH3 < 20 ppm  H2S < 10 ppm and CO2 < 3000 ppm). Check humidity (target between 50 and 75%). Check light intensity.  Check water supplies.  Check feeder space availability. Check 24 hour temperature fluctuations.  Mixing pigs.  Moving pigs.  Facial necrosis is associated with lactation failure.


Areas of Vice

Skin Vice areas copy


Note that postmortem findings can assist the veterinarian recognise that the pig was provided with a suboptimal environment which may have reduced the wellbeing of the pigs.


Examples of pathology indicative of suboptimal environments:

Injury to the skin – as illustrated in the previous picture.  Pulmonary millary abscesses, vegetative endocarditis, bacteriaemia, spinal abscessation and single or multiple discrete abscesses throughout the body


When the pig fails to adequately cope with its environment, the pig becomes compromised and unwell.  It often succumbs to pathogens demonstrating a variety of clinical signs depending on the pathogen.  The stockperson must have measures to cope with all compromised pigs.  Utilisation of hospital accommodation, suitable treatments and humane euthanasia where required.  Poor welfare is unfortunately often associated with stockpeople attempting to heal pigs that are too sick or economically incurable.


Interaction with man


When the veterinarian walks the farm, observe the pig’s behaviour to the stockpeople and yourself.  The pigs should come up to the fence line while you are outside their pen.  Enter their pen.  The pigs should move away initially, but rapidly turn and face you.  Then several members of the group will approach gaining confidence.  Within minutes the group will surround you and may even start licking and nibbling on your legs and clothing.  They can give you a particularly painful bite behind your knee.  These behaviours are more positive in large groups of pigs; small groups tend to be more nervous and reticent.


The relationship between human and pigs can have significant effects on the farm’s performance and wellbeing of the pig.  Handling studies have shown that pigs are very sensitive to brief tactile interactions from humans.


Observe the stockpersons reaction to the pig and look for positive behaviours and provide retraining to eliminate all negative behaviours.


Positive behaviours of the stockperson



Hand on the back

Talking to the pig

Squatting to the pig’s level

AI stockmanship with boar 2

Negative behaviours of the stockperson


Kicks not even forceful but also minor

Hits with hand or baton




Fast movements

(Note: The picture shown was staged)



It is important to realise that negative behaviours are not only about physical interactions but also body posture and general attitude.


If pigs see other pigs being positively handled they will reduce their own fear response.  Interestingly however, it a pig sees another pig being negatively handled it does not increase its fear response.  Pigs which experience negative responses from one stockperson will generally have fear responses to all people.  Therefore, it is important for all members of the team to have a positive attitude.


Permitted use of negative interactions

At times it is necessary to use negative interactions in the day to day husbandry of a pig farm, for instance when it is necessary to get the animal to move out of a pen.  It is also essential after utilising the negative action to enforce positive interactions once the animal is up and moving. This way the long term effect of the negative action can be nullified.




To audit a pig’s wellbeing, the veterinarian needs to familarise her/himself with all the normal repetoir of behaviour, expectations and characteristics of the pig at all the different phases of its life.

There are numerous audits being developed around the world.  Many of these programmes, while well meaning fail to be taken up by the industry unless they are legally enforced and then they are begrudged. 


To ensure that environments are provided which enhance the wellbeing of the pig the whole health team should enthusiastically collaborate and not require enforcement.  The provision of the suitable environment should be natural.  A veterinarian who focuses on providing an environment sympathetic to the pig’s need is more important than one who only measures the numbers of drinkers and then checks the box off the list.

This paper provides one idea of a methodology to enhance the wellbeing to pigs by attempting to provide the freedom to express normal behaviours.  The method demands that the veterinarian understand what are normal behaviours and then encourages the provision of an environment which allows its expression.  Expression of a normal repertoire of behaviours will maintain a pig’s wellbeing; enhance its welfare; provide an enjoyable environment for stockpeople and therefore enhanced profit for owners and farmers.  It is essential for successful and healthy farming to achieve all of these components.  If the pigs are allowed the freedom to express their normal behaviours and produce healthy meat with fewer medications, at a reasonable cost: the average consumer of their meat and other products will be more satisfied that the animal’s welfare is being satisfied.