Last week a commenter left a good question on our 6 Rules for New Pig Farmers post. So good, in fact, I thought it warranted a response in blog post form.
And since we’re currently in the process of expanding and adjusting our own pen infrastructure Chris’s question — “I was wondering what your recommendations for pen sizes?? And how much room do pigs need??” — really couldn’t have come at a more opportune time.
The best pen size for rearing pigs outdoors largely depends on four things: the number of pigs you’re raising in the pen, the shape of the pen, the footing in the pen, and the size/life stage of the pigs.
Contrary as it may seem, the more pigs you’re raising in a pen the less space they need per pig — at least to a point. This is because pigs tend to congregate together. At any given moment in time a large group of pigs in a medium sized pen will tend to use a smaller percentage of the pen than a small group of pigs in a small pen. When bedding down, for instance, pigs will virtually always choose to lay next to one another. This is especially true in cool and cold weather but rings true even in hot weather so long as shade and a wallow (or mister) are provided (and they absolutely should be.)
Generally, in a pen of any size pigs will have a sleeping area just large enough to accommodate the group, an eating area (wherever you choose to deliver their feed/water), and a urinating/defecating area (they mostly do this in one area of the pen naturally.) The remainder of the pen will be used for traveling from one area to another, exercise, and entertainment. Since all pigs will not be doing these final activities at the exact same time the larger the overall space for them the more pigs per square foot that can be accommodated. Whereas in a small pen the basic sleeping, eating, and bathroom areas encroach on the overall space to such a greater extent that fewer pigs can be accommodated per square foot of the remaining area.
I recommend beginning with the following stocking densities per group size and then adjusting the square footage allotments up or down according to the rest of the criteria described below.
41+Sq. Ft. per Pig
In virtually any group and pen size square pens are usually the best use of space. While rectangular pens can be used, and often are, they increase the amount of space needed per pig in order to avoid undue stress which can affect pig performance. In this case pig psychology plays a lead role in stocking density decisions. A long, skinny pen encompassing the same area as a square pen shouldn’t be filled as densely because it makes it harder for submissive animals to avoid dominant ones that may pick on them or push them around, especially when traveling from one area of the pen to another. Sometimes it even forces those submissive animals to cross paths with the dominant animals directly or results in them being trapped in corners. This can be an incredible mental stressor for the submissive pigs and may even result in injury and/or poor carcass quality in the case of pigs who were physically abused by their dominant pen mates close to market time. Even where physical confrontation does not occur stressed pigs do not perform as well as their calmer counterparts; they can require more feed per pound of meat produced and be more susceptible to illness. If your pens are rectangular rather than square allow more space.
Likewise, the footing in pens can allow for either lighter or heavier stocking density in pen rearing systems. Pens with footing that drains very well — such as gravel or sand — can accommodate more pigs than pens with footing that drains poorly or moderately — such as clay or heavy topsoil.* Because of the way pigs are built each of their pointy hooves bears an incredible amount of weight. This isn’t a problem in dry environments, but can quickly result in deep, soupy mud in wet conditions. Aside from being miserable to work in, mud in times of wet weather is not the pigs’ favorite environment, can result in feed wastage, and can contribute to illness and injury.
And last, but not least, the size and life stage of the pigs makes a big difference in how much space they need. Forty pound feeder pigs require considerably less space per pig than two hundred and sixty pound market-ready hogs, for instance. For growing pigs for pork in either backyard or niche setups I would recommend designing pen sizes to accommodate the largest size of pig or hog you’ll be raising. The exception to this would be farrowing and nursery accommodations on farrow to finish operations. Sows have different needs during and directly following farrowing than mature hogs of the same size. You’ll either want to design these facilities separate from the growing and dry sow/gestation facilities to avoid either having to vastly over accommodate the sows during the farrowing period or struggle with providing appropriate rations amongst other pigs. (More on where we stand on this in a soon-to-be-published post, I promise.) Similarly, nursery pigs require such vastly different (and more intensive) care than their older counterparts you’ll probably want facilities designed specifically for them, this may be within your growing facilities or completely separate, but the space allotment can certainly be an independent consideration and those facilities can be much smaller per pig than any others. (More on this later, too. Also, promise.)
I know it’s a lot to take in all at once, and I wish I could give you a hard and fast answer, but I’m afraid there’s very little hard and fast about it. Every operation is unique and, therefore, will have unique stock density needs and requirements. Instead, I’ll leave you with just a few points of advice:
1) Do not underestimate a pig’s ability to destroy ground, especially with the making of mud.
2) Err on the side of over accommodation, you can always add more pigs to your pens. It’s much harder (and more expensive) to build new pens. On this I speak from experience.
And 3) Consider everything from the pig’s perspective. Don’t just look at the size of the pen, look at the way the gate opens relative to obstacles and the planned route of loading pigs out onto trucks and into other pens or pastures, pay attention to changes in the ground structure (pigs have poor eyesight and often balk at ground coverings they don’t recognize), consider wind direction when placing shelters, sun source both for hot months (when you’ll want to block it) and cold ones (when you’ll want to capitalize on its light and warmth), and so on and so forth.
*Concrete pens can alleviate the mud/footing consideration entirely, but presents its own host of issues. It holds heat during the summer months, increasing the need for cooling measures to avoid overheating hogs, and can result in joint injuries, illness, and lameness.