[90driver]

For the past 3 years we have been fattening up weaners in batches of 3 . We do 2 batches a year and leave their field to rest over the winter. This year the wet weather has meant that they have completely trashed the field and before the next lot arrives I want to fence off another field. The current field is 20m x 35m and the next one may be slightly larger. Was just wondering what areas others set aside to raise their pigs ?

[oaklandspigs]

copy of an answer I did a while ago for someone who asked 'how much space do I need?' 

Area needed for x pigs is the pig equiv of “how long is a piece of string”, so I will try and explain criteria...
The Welfare of Farmed Animals 2007 (in England and Wales) have a number of rules, which include that “ A pig must be free to turn around without difficulty at all times”...”allow each pig to stand up, lie down and rest without difficulty; have a clean, comfortable and adequately drained place in which it can rest; maintain a comfortable temperature; and have enough space to allow all the animals to lie down at the same time. Minimum dimensions for a stall or pen used for holding individual pigs must be such that the internal area is not less than the square of the length of the pig, and no internal side is less than 75% of the length of the pig, the length of the pig in each case being measured from the tip of its snout to the base of its tail while it is standing with its back straight.” There are additional provisions covering farrowing and examination, but the above is the guts of the accommodation regs.
Ok so that’s the law, but doesn’t really help us much.
So let’s start with the basics.  A pig needs space for 4 things – a space to sleep, a space to eat, a space to dung/pee, and a space to exhibit natural behaviour – the last one defined in the act as “proper investigation and manipulation activities” , but to us it is to root!
On indoor commercial, they use slats for the space to sleep and dung so this area becomes combined, and food/water are in very small troughs above the floor.  Exhibit Natural behaviour is achieved by adding materials such as straw or chains.
These same regs apply indoors & outdoors, but clearly outdoors, no-one (I hope) would hold animals anywhere near the density allowed.
So externally you need to consider the same 4  things, space to sleep, space to eat, space to dung and space to exhibit natural behavior. We can add one other to our outdoor list, that is enough space to maintain a reasonable environment. So 5 things to consider.
Sleep
So for sleep this is typically an ark, job done, no more space needed or not? Provided your ark can maintain a comfortable temperature eg straw in winter, and plenty of ventilation in summer, otherwise add a shaded area to sleep outside in hot months.
Dung
Pigs will not dung on top of dung.  Therefore their dunging area needs to be big enough to allow time for nature to dispose of dung, and for you to keep the sleeping and feed areas separate.  The pig will decide the dunging area, just watch and make sure it is not encroaching on where you feed.
Feed
If you feed nuts in a trough, on slabs or straight onto the ground, there needs to be sufficient space for all the pigs to eat at once (again welfare of Farmed Animals acts says “each pig must have access to the food at the same time as the others in the feeding group”)

Exhibit natural behaviour
Ok so after this we get to the tricky parts – how much space to exhibit natural behaviour do we need – ie how much to root/dig, and how much to wander around.  The law states no requirements, so this is up to you to decide.
The smaller the area, the quicker it will be trashed, The larger the area, the larger we have to fence, protect, look for pigs etc. and of course it is land we can’t use for other things.
Maintain a reasonable environment.
Obviously we want the area or areas we provide to be suitable for the pigs to move around in, and the smaller the space, the more quickly it will turn to mud in winter or bad weather. Whilst your pigs will be quite happy in mud that you find difficult to keep your wellies on in, too much for too long is not good for them.



So why can’t I just state for x weaners allow y sq. Metres to satisfy behaviour and environment?

Well lots of factors affect how many pigs you can keep on a piece of ground. These include in no particular order (and there are probably many more):
Type of soil  - how easily drained or gets waterlogged
Type of cover  - the thicker the cover, the longer to work it out, the smaller area needed.  Woodland areas can be smaller than field, thick cover even smaller.
Slope – pigs don’t really like steep ground, but no-one has billiard table, but more undulating the bigger the area per pig needed.
No. pigs kept together - a pen of 20 pigs need less space than 2 pens of 10.
Type of pigs – just weaners to fattening?, breeding sows, baconers? Larger pigs need larger space.
All year round? – just keeping pigs over the summer, less ground needed.  All year round, probably needs a couple of areas to let one rest and recover.
Prevailing wind – how quickly does the ground dry up after rain, is the prevailing wind warm and west, or cold and north. 
Exposure of ground – very exposed ground will not be well utilised by pigs, so a large area is a waste of time unless you shelter it (eg willow screen)
Geographic location – the further north, the shorter dry and warm summer, so the more ground needed to maintain environment.

So does this very long answer to your "quick question" help you - probably not, but it does help explain why there are no "forumulas" for this, and will hopefully let you think about not only how much, but to know why.

[90driver]

Thank you for your very detailed reply. Very useful for all of us.

With 3 almost finished pigs in a  700square meter enclosure sounds over the top but they have destroyed it this year,  they have plenty of room to run about like lunatics, which is fun to watch.  The second enclosure will be the same if not bigger. At least that means we can keep lager numbers when we need them.

[benkt]

If it helps have another data point, we have three pens for pigs, two  of approx 25mx25m for younger weaners and a 25mx50m pen that we move them into for the last couple of months (easier loading from that pen into the trailer at the end). We do batches of 4 or 6 at a time between Feb and Nov. We are on heavy clay soil but the pens are very green - not to say a little overgrown so definitely big enough for all their rooting needs!

[greenbeast]

If it helps have another data point, we have three pens for pigs, two  of approx 25mx25m for younger weaners and a 25mx50m pen that we move them into for the last couple of months (easier loading from that pen into the trailer at the end). We do batches of 4 or 6 at a time between Feb and Nov. We are on heavy clay soil but the pens are very green - not to say a little overgrown so definitely big enough for all their rooting needs!

We do have larger batches but i'm surprised you still have green in those pens! Ours make short work of the ground here

[benkt]

We've found having a break over the worst of the weather from Nov to Feb gives the pens a chance to get overgrown and then the pigs don't manage to trash it in the time they are given!

[greenbeast]

Nice, we have learnt from our first winter, and will be using our various pens (and building  more) to cope with winter better