Ethology and WEthology and Welfareelfare of Pigs of PigsChapter 1Chapter 1

Author: RNDr. Marek Špinka, CSc.

Evolutional Lineage of Evolutional Lineage of Domesticated Pigs‘ Behaviour Domesticated Pigs‘ Behaviour Domesticated pigs are descended from the wild boar.Domesticated pigs are descended from the wild boar.

Through Through domestidomesticcaationtion a andnd breeding, the wild boarbreeding, the wild boar’s ’s behaviourbehaviour was made calmer and less active.was made calmer and less active.

However, theHowever, the p primary behavioural patternsrimary behavioural patterns ( (feedingfeeding, soci, sociaal, l, agagggresresssivivee, mate, maternal, etc.rnal, etc.) ) were were left unchanged.left unchanged.

Domesticated pigs inherited their ethological needs from their ancestors in the wild.

Sensory Perception and Communication

Scent – the Most Important Scent – the Most Important Sense of Perception in PigsSense of Perception in Pigs

Pigs use scent during:

Feeding

Distinguishing of individual pigs

During signalisation of danger, via

pheromones.

Pigs are able to smell signals that humans cannot.

Example of the Importance of the Sense of Smell to Pigs

It has been proven by experiment that a sow cannot distinguish her piglets individually until the second day after birth.

Practical result:

a mother will happily rear spurious piglets.

Hearing is Important for Communication

Examples of vocal communication:

The piglets synchronise the rhythm of their suckling to the mother’s grunting.

Sows react to piglets‘ squealing by immediate readiness to protect them.

Too much noise in the stalls impairs

communication between pigs.

An eAn example of vocal communication: xample of vocal communication: a a lonely lonely piglet calling its motherpiglet calling its mother

Sense of Touch - Important during Interactions with Surroundings

Uses:

searching for food,

exploring new objects,

suckling – by massaging the sow’s teats, piglets trigger the ejection of milk.

Social Behaviour

Pigs are Social AnimalsPigs are Social Animals

The natural number of female pigs in a group is 3-8.

There are strict hiearchical relationships inside the group.

Pigs strongly protect their territory – unknown pigs are unwelcome.

Pigs should be kept in stable groups.

Meeting of Strange Sows Always Leads to Fights

Fights are most intensive during the first few hours after meeting.

Increased aggressivity lasts for a few days.

Wounds from fights are slight, but the stress is sizeable.

Groups of sows should be mixed as little as possible.

Group HierarchyGroup Hierarchy

Sows naturally form a stable group hierarchy, with a low level of aggressivity.

When establishing the hierarchy, the dominant sow will attack a submissive one, pursuing from a distance of about 1-3 meters.

Therefore, the wall of a group stall should be at least 3 meters long, so the submissive sows have room to retreat.

Feeding Behaviour

Digging

It is in pigs’ nature to obtain most of their food from the soil.

Pigs need to spend part of their time digging in a suitable substrate.

Pigs kept in stalls should be provided with bedding. It will satisfy their need to dig.

Chewing

Pigs, as descendants of the wild boar, have a natural inclination toward a mainly vegetable diet, with a high proportion of fiber.

Pigs need to spend a considerable amount of time chewing their food, even if they get a high energy food.

Straw satisfies pigs‘ need to chew.

Bar bitingVacuum chewing

An unsatisfied need to chew leads to:

Caused by a lack of bulk feed.

Caused by a combination of starvation and restriction of movement.

This is a prime example of abnormal behaviour, and is a sign of compromised animal welfare

Social Hierarchy and Feeding

Pigs need to eat together with other pigs.

Dominant pigs eat preferentially.

Conflicts during feeding lead to fights and prevention of access for inferior pigs.

Pigs must be enabled to access the feed all at once, or the eating individual has to be protected by a feeding machine.

Maternal Behaviour and Behaviour of Piglets

Pregnant Sows Build a Nest Before Delivery

In natural conditions, pregnant sows build a nest 1-2 days before delivery.

Sows housed in stalls still have a need for suitable material to collect and arrange into a nest prior to delivery.

It is essential to provide sows with appropriate

bedding material with which to build a nest before

delivery.

Sows Lie Down During and After Delivery

During delivery, and for about 12 hours after, a sow calmly lies down.

Newly-born piglets independently look for a teat to suckle colostrum.

Sows don‘t mind restricted movement at this time.

Danger of Overlying

A piglet weights only 1 % of sow‘s bodyweight.

The danger of overlying lasts for about 3 days after delivery.

Piglets can be protected either by a farrowingcrate or by sow‘s natural behaviour.

milk ejectionmassaging of teats

Suckling is a complex interaction comprising

expulsion of milk

enables suckling

stimulates sow‘s

teats to eject milk

(see the following pictures)

Vocal communication

Function of grunting: to synchronise behaviour of the sow and her piglets

Vocal communication during suckling:

1. grunting of the sow

Function of ”croaking“: signals pig‘s identity, and strenghtens the mother-piglet relationship

Vocal communication during suckling:

2. ”croaking“ of piglets

Function of squeaking: signals the broken order of teats to the sow

Vocal communication during suckling:

3. squeaking of piglets during a fight for teats

Playful Behaviour

Playful behaviour is usually observed in piglets 2-6 weeks old.

Social playful behaviour can appear to be fighting. However, no injuries occur.

By playful behaviour, the piglets train their social and motor skills.

Piglets’ should be housed with sufficient space and bedding to allow for playful behaviour.

Weaning – Loss of Mother

The natural age for weaning of piglets is around 12-18 weeks.

If weaned early (3-4 weeks or sooner), piglets have an unsatisfied need to suckle.

This results in the massaging of the bellies of other piglets, a form of abnormal behaviour.

Piglets shouldn‘t be weaned before their 28th day.

Weaning – Multiple Stresses

During weaning, the piglets are exposed to

multiple stresses:

loss of their mother,

loss of milk,

shift to a strange environment,

mixing with strange piglets, resulting in fights and injuries.

It is desirable to separate these stresses: first, segregate the mother, leaving the piglets in their original environment. Wait a few days, then move the piglets.

Housing and Behaviour

Proper housing should provide a pig with:

room to rest peacefully,

proper bedding, by which a pig can thermoregulate

(if this is not provided, the air should be regulated),

separate space for defecation,

stimuli for expressing their natural behaviour,

safety from fear of man/farmer.

lying on a cool surfacewallowing

Thermoregulation in Hot Environment

The pig wets its body in

water, mud, and

eventually in excrement.

Heat is released through

evaporation.

The pig cools its

body through a

convection of heat

to the cold floor.

Pigs are not able to cool themselves by sweating.

In high temperatures, they lower their body temperature by thermoregulation:

physical contact bedding

Thermoregulation in Cold Environment

burying themselves in straw reduces

heat loss

resting in close

physical contact

reduces heat loss

Pigs also thermoregulate in low temperatures.

Natural and Functional Division of Housing

The size and arrangement of the stall should allow pigs to carry out different ativities in separate areas of the stall.

resting – in dry, quiet spots

by wallsdefecation - in cool, wet

spots

activity – in a free space of the stall

Poor and Overcrowded Housing:

disables functional division of the stall,

does not offer a permanent place for rest, which

leads to distress,

doesn‘t support creation of a separate place for

defecation –> the animals and stall are unnaturally

dirty

The housing should provide pigs with a chance to functionally divide the stall.

tail biting

cause: no bedding

two different solutions

tail docking - solves

the consequences

Abnormal Behaviour and the Environment

provide bedding -

solves the cause

Human-Animal Relationship

Rough handling causes stress, and fear of humans.

This impairs sows’ reproduction.

A good attitude towards animals makes work in a stall more interesting and brings more satisfaction to the workers.

Kind handling also improves productivity, and has direct economic results.