Behvaviour and habits of pigs


“They looked from pig to man and man to pig and could not see a difference” (Animal Farm, Orwell)


Understanding the normal behaviour and habits of pigs is an essential precursor to designing suitable accommodation for pigs and thus maintaining their health.  With the increase in total born and thus numbers weaned a rethink of the buildings currently in use may be necessary to provide an adequate environment for the pigs.


Pigs in the wild

Pigs (Sus scrofa) have evolved from living in deep thick European forests.  But they have proven to be extremely adaptable.  Naturally the Suidae have adapted and colonized all global climate zones – below the snow line. They are one of the most successful families of mammals.

The only real difference between man and pigs is that Homo sapiens are African with a temperature comfort zone of 24°C whereas Sus scrofa are European and are more comfortable at 16°C


A wild boar in a modern environment?

Being sympathetic to the needs of the pig produces better environments for production.


What are the basic behaviours to consider?

Sleeping    Defecating

Eating                  Drinking




Pigs, especially young growing pigs, sleep most of the day.  The sleeping area is therefore an essential component to the design of the pen.  Unfortunately, most pig buildings provide adequate lying areas – but poor sleeping areas.

Pigs require a sleeping area which is dry, draught free and at the correct temperature.   There is required to be sufficient space for all the pigs to find a place.  Pay particular attention to the sleeping area.


Each day stockpeople should examine their pigs to check they are sleeping comfortably.  The first concern is that there is sufficient space.  When the stockperson enters the house, they should do so quietly so as not to disturb the sleeping pigs. Observe and understand their pattern around the house.

This can be easily achieved by having a window looking into the house.  In the picture above, not that one pig (arrowed) is sleeping outside the main pen.  This pig is under the most stress and is the most susceptible to pathogens.


It is vitally important that the stockpeople understand the different postures portrayed by sleeping pigs and correctly interprete their meaning.

Too cold


Lie 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. Pigs sleep with legs stretched out from the body.



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 and can destroy the building

The sleeping and lying pattern and the posture of the pigs provide an acute indicator of pig comfort.



Pigs are inherently clean animals and avoid lying in faeces.  From a few days of age pigs will become toilet trained to defecate in a specific area of the environment.  This can be classically seen in outdoor reared pigs.


The defecation pattern of the pen provides a good long term (chronic) indicator of comfort. Abnormal defecation patterns indicate a chronic reduction in optimal environment. The defecation pattern can be extremely useful as any member of the health team can easily see and map out the area, even without the pig’s presence.     When the pigs leave a building, examine the defecation pattern and explain any unusual pattern.  The problem, normally with the ventilation system, must then be resolved before the next batch of pigs enters the building.


Pig’s defection area can be expected to be either

Where the pen has a draught – the pigs will defecation under the cold dropping air (blue in the picture).  This area is normally the coldest

Where the pen is wettest – note the faeces under the drinker

Where the pen is darkest and most private.  This may often be by feeders.


Hot pigs will specifically choose to wallow in faeces 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.


Note the pig’s in the picture are lying by the drinkers – another abnormal position




To provide comfort while eating it is essential to provide sufficient feed space.  The feeding space is dependent on the type of feeding system employed – either adlib or restricted.

Feed space allowance with age/weight of the pig

Weight of pig

Trough/hopper length/pig


Restrict feed mm

Ad Lib Fed mm























400 - 460



The most important time when this becomes significant is in the first week post-weaning.  At this time the newly weaned pigs feed as a group and therefore, require 100 mm per weaners.  Unfortunately, majority of farms fail to provide sufficient feed space and thus restrict feed intake and therefore growth post-weaning.   Examination of many pigs which fail post-weaning find an empty stomach and villus atrophy and fusion in the small intestine.

The stockperson should examine all the pigs, at least once a day, when they are eating.  With adlib feeding to examine each pig’s eating pattern pattern would take considerable time.  With restrict feeding; examination of the pigs is easier as they all eat at the same time.   Any pig which fails to enthusiastically eat with its peers can be rapidly recognised and marked for further investigation.

The stockperson must first notice the pig on its own and then ask the question “why”?

The best indication that the feed is adequate is to examine the growth rate of the pigs.  To provide an indication of the growth pig every-time a pig is moved, it should be weighed. This will then provide at least a couple of points on the growth curve – at weaning, at 10 weeks from the nursery to the grower and the age and weight at slaughter.



The growth rate of pigs is a good indication of health.


Stockpeople are required to understand the daily water requirements and the behaviour of the pig while drinking.  On many farms water is taken for granted.  The stockperson does not think “pig” enough to appreciate the difficulties their charges may have in obtaining a drink.

Pigs which have restricted water supplies will both grow slower and have more diseases.

Classical indicators that there is a problem with the water supply would include:

·   Left feed

·   Dirty drinkers

·   Pigs drinking all night

·   Crowding around the drinkers



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 gain comfort and support from other pigs and/or other animals.  Pigs should not be kept in isolation, including boars. 

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 have a generally 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 chop straw even while being housed in stall accommodation between weaning and pregnancy checking.

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.  Avoid tires as they contain metal parts which can be swallowed by the pig.



How can all of these behaviours be applied to enhance pig health?

This paper has briefly examined five areas of normal behaviour with which all stockpeople must become familiar.  There are other behaviours, not examined here, which apply to individual areas of production, farrowing and breeding for example.

However, using these five behaviour areas, a better building can be designed which promotes health.


For example, the design of the nursery.

A pig to 30 kg requires 0.3 m2 total floor space. 

The pigs require one water nipple drinker to 10 pigs or one water bowel to 20 pigs.

Feed space requirement at weaning is 100 mm per pig for the first 3 days, afterwards 50 mm per pig to 30 kg.   The farm uses 50 cm wide feeders. 

Air movement should be less than 0.2 m/s in the sleeping area.  Ambient air temperature in the sleeping area should be 30°C at weaning to 24°C at 30 kg.   The sleeping area needs to be draught free.  There is no specific temperature requirement for the rest of the housed area. 


The total unoccupied floor area is:

(2*3 m pens)*8 [pig floor area] minus (1*0.3)*8 [feeder space]

This equals – 48 m2 – 2.4 m2 = thus a total unoccupied floor area for pigs is 45.6 m2

30 kg pigs require 0.3m2 per pig.  Thus a total of 152 pigs can leave the nursery.

Note if this number is not whole, the number needs to be rounded down.

With a 97% nursery survival rate =  152*1.03 = 157 weaned pigs which can enter the building. 

With 10 weaned per farrowing place – this results in 16 batch farrowing places.

With a 10 c differential between cost of production and income and 95% finishing rate (survival rate to slaughter) this results in a profit of about 1200 € per batch

Traditional nursery design

Floor plan and cross-section of the room demonstrating air movement.





On this farm there is poor space utilisation – the passageway is 8m2 – room for 27 pigs which would be high profit pigs as the fixed cost of production has already been paid for.

There is a differential air temperature and speed around the house. The pen nearest the door   is colder and has more draught than those by the outlet fan. The whole house has to be at 30°C as the pigs are expected to sleep in all the pens – despite the fact that some pens may have a draught.

The water supply is along the whole house making the defecation area to also be along the outer wall – which reduces the optimal sleeping area for pigs. Pigs like to lie against a wall.

The feeder spaces are rectangular their position demands a long feed line.  The pens are not wide enough to allow for adequate feeder space in the critical 3 days post-weaning when the pigs are restrict fed rather than adlib at which point they require 100 mm per pig.


Modification of the building to accommodate the pig’s behaviour and habits


The building design utilises the whole floor area.  The use of circular feeders reduces the space occupied by the feeder.  Thus the number of pigs which can occupy the building at 30kg can be calculated:

8*7 m2 [Floor area] minus (0.785*0.7*0.7m diameter*2) [Feed area] = 55.13m2

This provides space for 55.13/0.3 pigs = 183 pigs

The temperature can be differentiated to provide 30°C in the sleeping area for the newly weaned pigs and a cooler 24°C in the drinking system. This increases the ventilation in the room which reduces humidity and enhances the respiratory tract defence.  The cooler area also enhances feed intake.   There is sufficient space, to allow for the sufficient feeder space for the first 3 days post-weaning.

The ventilation system allows the room to provide clear occupation zones with defecation and sleeping areas being clearly separate.

The central feeders can be fed from a single feed auger going between rooms reducing the length of the augers.

The enhanced use of the floor space providing room for more pigs increases the profit potential out of the building.  As the world accommodates the recent increase in weaned numbers per batch farrowing place, this room provides room for 12 weaned from the 16 farrowing places per batch.  The increase in the number of these marginal pigs increases the profitability of the batch to over 2300€ per batch.