27 September 1996


Pigs see their surroundings from a viewpoint under a metre from the ground and their poor eyesight causes them to baulk at unfamiliar objects. So when seeking to improve pig flow, look at objects from pigs eye level. Jonathan Riley reports

PIG buildings designed carefully improve the flow of pigs, cutting labour inputs and reducing stress levels of stock and stock carers alike.

This is the view of ADAS researcher Hans Spoolder. He says passageways and handling systems should be designed so that minimal encouragement from stock carers is needed to create a steady flow of pigs.

"Stress for pigs and stock carers is increased when pigs are moved. Trials in the UK and Australia have shown that when pigs are handled badly, growth rates fall and the likelyhood of poorer reproductive performance is increased," says Mr Spoolder.

He suggests, therefore, that when designing or improving pig handling systems and passageways around the farm, producers should try and appreciate how the pig sees objects in its path.

"A pigs eyesight is relatively poor and it relies more on its nose for information about its environment. When the pig is faced with a confusing scene such as a bright light it will stop. Stock carers then have to intervene, increasing labour input and increasing stress on the pigs and themselves," he says.

Mr Spoolder advises that anything in the path of the pig that could confuse or distract it should be redesigned.

He explains that pigs are very inquisitive and passages within buildings should always be clear of feed. Barred gates used for pen fronts will allow pigs contact and inevitably cause them to stop, possibly spreading disease.

"The flow will also cease if, when moving pigs down a passage to an open pen, a pig is confronted with a solid gate opened out across the passageway. From a humans viewpoint it is easy to see the pen opening on one side of the gate.

"But all the pig may see is a solid board across the passageway which looks like a dead end," says Mr Spoolder.

"In this situation pen doors that open 180í and a barred gate placed across the passageway would allow pig to see beyond the barred gate. This should encourage the pig to continue moving for longer and as a result it has more chance of seeing the pen opening," he says.

Similarly right-angled turns at the end of a passage will appear to be a dead end from pig level, and Mr Spoolder advises cutting across the pen corner so that the passage turns in a series of bends.

"A pigs main sense is its nose which it uses to assess changes in floor levels. When pigs reach a step down their noses lose contact with the ground and they could baulk. So replace steps with gradual slopes.

"Loading ramps and slopes up to buildings always look more daunting from a pigs perspective. So again, where possible level out ramps and provide raised loading bays for lorry tailgates to drop onto. And avoid loading pigs up ramps into the sun because the strong light will confuse them. When moving pigs out of a building into daylight, stronger lighting could be provided in the building immediately before the exit. This will lessen the contrast between the daylight and the light level in the building.

A clear plastic awning outside doorways can also help by diffusing light outside the entrance making the transition into daylight more gradual, he adds.n

&#8226 Increases stress for pigs and stock carers.

&#8226 Increases labour input.

&#8226 Can spread disease.


&#8226 Avoid spilled feed.

&#8226 Avoid passageways with right angled bends.

&#8226 Replace steps with ramps.

&#8226 Provide raised loading bays.

&#8226 Improve lighting near exits.



&#8226 Eyesight is poor.

&#8226 Eye level is under 1m from the ground.

&#8226 Pigs use their noses to assess changes in flooring.

&#8226 Pigs are inquisitive and will stop to examine unfamiliar objects.

Above: A ramp seen from the stock carers eye makes it difficult to see why these pigs are hesitating at the bottom. Below: Seen from the pigs eye level loading ramps and slopes are a much more daunting obstacle.