WARNING!If you are a person with too sharp a pencil please put it down. You can not take numbers from one situation and misapply them to other situations willy-nilly. Each pasture is different. Pig sizes and ability to digest forages varies. Pastures vary with the season. Things change over the years. Management techniques are adjusted. How I do things in 2001 is not going to be the same as I do in 2011. How many acres we have open for pasture does not stay linearly smooth with how many pigs we have – e.g., in 2009 we cleared a large new section of fields but we didn’t all of a sudden quadruple the number of pigs we had. There are too many variables to apply numbers as absolutes and expect graphs to all look smooth. Instead, use the article below as a guide to give you a feel for one situation. Now relax and enjoy…
On the post “Keeping a Pig for Meat” Bill asked:
Some questions: I understand you have plenty of land for pasturing, so smell in minimized and the rooting and damage is not spread beyond the land’s capacity to continuously rejuvenate. How much would you think is the minimum to pasture a single pig?
The pigs don’t smell bad out on pasture. The association with stink probably comes from pigs that are confined. The same happens when you confine cows, sheep, chickens, people, etc. Additionally, pigs on pasture eat a great deal of fiber which is high in carbon and I suspect that the carbon in the grasses binds the nitrogen and other chemicals that cause the smell associated with manure. This is important to conserving the valuable fertilizer. If you can smell it you’re losing nitrogen and other useful elements to the air – fertilizer that farms pay big money for.
Rooting is not very deep, typically only a few inches, and is actually good for the soil. If you’re looking to have a fancy suburban lawn then pigs are not ideal. But they will to a wonderful job of renovating old pastures like we have, gradually improving them without ever bringing in a bulldozer or bush-hog. Combine them with sheep and chickens and you have a great grounds crew.
As to how much land for a pig, we currently have about 200 pigs of varying ages on about 10 acres divided into paddocks. The pigs, divided into two herds, typically get access to one paddock at a time. That is right up at the current limit for our fields and we’re about to create more fields so we’ll have a lower stocking density which makes management easier. Our pigs range in size from little piglets of three pounds or so to big sows and boars of about 600 to 800 pounds. I would guess the total herd weight at about 40,000 lbs right now. It could be significantly more although it is biased toward the younger ages at this time. That is about 4,000 lbs per acre or about 20 finisher pig (200 lb) equivalents per acre. Remember they’re moving, not sitting.
Note that in addition to the pasture our pigs also get whey from cheese and butter making at the rate of about 2.5 gallons per hundred weight per day, some cheese trim, excess milk, cottage cheese, the occasional bread, occasional spent barley and excess from our gardens. Thus they are not getting 100% of their food from the 10 acres of pasture. If I only had the pasture I would probably only have about 25% to 50% as many pigs on it, so about 10 pigs per acre.
Another important consideration is the quality of the pasture. Forage varies greatly from scrub to lush legume pastures that are high in protein and that will make a big difference in the carrying capacity. Our pasture is about half brush and regen (young sapling poplar trees) with grasses beneath and over seeded with clovers. This is savannah style pasture rather than lawn like pasture many people picture. In time I expect to gradually further improve the pasture which will increase its capacity. The animals improve the pasture through their grazing, rooting and fertilizing. Liming also helps to raise the pH of our acidic soil to something more hospitable to grasses and high protein legumes.
Some interesting math:
1 acre is about 200 feet x 200 feet
10 acres is about 400,000 sq-ft
200 pigs on 10 acres is about 2,000 sq-ft per pig
or about 10 sq-ft per pound of 200 finisher pig equivelant
or about 20 finisher pigs per acre on average.
Again, remember this is a moving herd, not sitting in one spot. For figuring stocking densities I tend to use the number of ten pigs per acre. Note that gives our average pig size at about 100 lbs which is probably about right with a distribution of some in the large sizes (sows & boars) and many in the small sizes (piglets & growers). Currently our herd is a bit skewed in sizes as can be seen in the recent photo above. That changes over time, of course.
The (il)logical extrapolation of all that is 10 square-feet per pound of pig if you are giving supplemental feed – Thus for a single finisher pig it would be 2,000 sq-ft per pig or about 20′ x 100′. That is about 1/20th of an acre. I suspect you’ll get soil compaction and too much rooting with such a small area. I would suggest an eighth to quarter acre or so if it is done with four to six managed intensive rotational grazing paddocks. Depending on the season and the quality of the pasture you may or may not need extra feed.
As I mentioned before, our pasture is running at about it’s carrying capacity right now. This is because we have fairly poor, acidic, low quality, thin mountain soils. Things are getting better. As we lime the soil it increases the pH which improves the growing conditions for grasses and legumes like alfalfa and clover. As the pigs graze they are also pooping and urinating which spreads fertilizer over the fields. The whey and other good food they eat gets turned into pork but also about 75% of it passes through them and gets excreted adding to the fertility of our soils. In time our soils will improve. If you have rich soils and good pasture you can probably have a higher density of livestock than we can.
Of interest: In concentrated feeding operations (CFOs a.k.a. Factory Farms a.k.a. the Evil Dark Lords of food production) they allow that the “generally accepted space per pig during finishing is 8 square feet. That is a 2′ x 4′ closet. The average finisher pig is about 4′ x 1′ x 18″. Modern office cubicle workers are allowed slightly more at a typical 5′ x 5′ or 25 square-feet per worker (averaging 5′ 9″ x 14″ x 14″). Our tiny cottage is 252 sq-ft for the five of us or about 50 sq-ft per person. Fortunately, we, like our pigs, don’t spend our lives indoors all the time and we have shared spaces. Unlike the pigs, we monkeys make use of vertical spaces too. :-)
Realize that 75% to 80% of the time, at least 21 days and preferably 30 days per grazing cycle, the land is resting and re-growing. The livestock are only on a section of field for a short period and then they move on to greener pastures. When we move pigs we truly are taking them to a better place.
You might also be interested in the article South Weaning Paddock which describes a weaning setup that is 100’x100′ divided into ten paddocks. That’s a quarter acre and large enough to raise two or three pigs all the way to finisher size using the managed rotational grazing. It is an example of doing it on a very tiny scale.
Some Related Reading:
One Day of Rotational Grazing
How Much Land Per Pig
Pasture Post Pig Grazing
InstaPigs and Animal Units
North Home Field Sow and Piglets
Sugar Mountain Farm Pigs: Feeding and Grazing
Vet Visit Field Tour
Painted Probed & Pierced Pigs
Sorting and Driving Pigs
On a totally different topic, I had an interesting temperature reading today
on the tiny cottage. The temperature is normally in the mid-60’s to low-70’s F which is due to the massive nature of the concrete and stone construction (100,000 lbs). Today the tiny cottage high was 55°F and the low was 53°F. Admittedly we haven’t had any sun for a few days but that seemed oddly low. Then I discovered that I had left the bathroom window open for two days and nights… Oops. I had been ventilating after using silicone. What is amazing is that the outdoor temperature dropped to 38°F and the tiny cottage still only went down to 53°F. Pretty good for an unheated shell.
Thursday-Friday Outdoors: 57°F/38°F Overcast, 4″ rain, high winds
Farm House: 68°F/63°F
Tiny Cottage: 55°F/53°F Window left open over night, attic forms work