I've been raising pigs primarily outdoors for the better part of the last decade, and I've read a lot of people who "pasture" their pigs, and there's some of those folks who claim that the pigs get all of their dietary needs from "pasture". I'm writing this post as a summary of a decade of experience.
In this post I'll be using some photos from various sources; I do that for educational purposes, and in some cases I've used the photos despite being specifically forbidden from using them. Here's why I'm doing that:
One of the biggest proponents and advocates of pastured pigs isn't doing anything like managment intensive rotational grazing, despite years of claims to be doing so; in my opinion. His farm name and blog are on the photos I'm using to illustrate this post, and he's welcome to say whatever it is he'd like in response, but I think you'll agree that discussion of farming practices is best when you get all sides of the issue.
one of my sows grazing on my alfalfa from Bruce King on Vimeo.
"Pasture" definedThe first thing to do is talk about what people mean by pasture. I've visited a lot of farms over the last decade; more than a hundred. Pigs, when they're kept outdoors, have had areas that ranged from bare dirt and rocks to lush growth, and in every case the farmer called it "pasture". For the purposes of this discussion I'll talk about pasture as being any outdoor area that is used to raise pigs; it may contain trees and brush, or be grass or a planted crop like alfalfa, or it may contain a mix of different plants or it may have no plants left there at all; bare dirt and rocks. "pasture" is any outdoor area where you keep pigs while you're raising them.
There's no minimum size for "pasture"There are no minimum size qualifications for "pasture". I've heard people refer to a 20x20 pen as 'pasture', and I've heard others refer to 70 acres as 'pasture'.
What does Management Intensive Rotational Grazing (MIRG) mean?MIRG describes a system of moving animals over the land, allowing them to consume some portion of the vegetation there, and then moving the animals to another spot, allowing the vegetation to recover from the grazing.
The theory is that confining the animals to a small portion of the land, the plants that the animals like are consumed, and those that they don't like are either trampled or manured to death. Once the acceptable level of grazing has occured, you move the animals to another area, and you want the rest perioed between visits to be long enough to break parasite lifecycles. An additional theory is that you can improve the effects of this rest period by putting different kinds of animals out in successive waves -- cows first, for instance, and then chickens to scratch apart the cow patties for the fly larvae which would otherwise hatch and bother the cows.
An additional benefit is that you are able to control where the animals spend their time. Generally speaking critters will hang out in areas of your land that they prefer -- a shady tree, or nearby a water source, and those "camps" become areas where parasites thrive and re-infect the animals. Presenting new, parasite-free ground reduces that.
It's an attractive scenario -- appealing to those folks who want to think that t hey're recreating the grazing of large herds of herbivores, and replicating natural pest control. For a variety of reasons, if you visit a livestock forum you will often find many discussions of this form of land management for livestock.
Why is it "Management Intensive"?
This term refers to the amount of work that it takes to actually do this sort of management. Traditionally in the USA most cattle are managed on a "free grazing" system. This basically involves putting a perimeter fence around the land, and then turning the animals loose in that area to graze whereever they want.
No fixed permanent feed or water stations
If a farmer is going to practice this form of pasture management they can not use fixed, permanent feeding or watering stations; they must either have a lot of interior fencing, or the ability to temporarily fence smaller areas to restrict access. More to the point, they've got to move all of the equipment for the animals each time that they move the animals, or provide new equipment at every new paddock. Fixed feeding and watering stations rapidly become the center for parasite infection, and often will show intensive wear and tear on the vegetation. Very often they become bare earth or mud.
Moves are based on the vegetation consumption rate
In addition to moving the fencing, equipment and animals, the farmer needs to keep a close eye on the vegetation itself, and to learn and work with the growing season of their farm and land. For most of the world there's a part of the year that plants don't grow; out of the standard growing season it doesn't matter if there's a 6 month rest between grazing if it's too cold, or too hot, or too dry, or too wet, for plants to grow.
Management intensive = your time and attention
You're moving animals, fences, equipment and water, and you're doing so on a semi-random basis based on how fast the animals eat the vegetation that you provide. That's why it's called Management Intensive. It takes your time and attention.
How much vegetation can you graze off before you move the animal?For most proponents of rotational grazing systems, one simple way to tell if you've taken too much is when you see bare dirt. Bare dirt means that all of the above-ground plants are gone, and probably some of the roots, too. Taking grazing down to the bare dirt means that the plants will have a harder time recovering, take longer to recover, and generally speaking it means that the favorite plants of the grazing animal are usually completely eradicated; weeds grow faster and larger than palatable plants for the most part. That's whe they're weeds. I have grazed down to bare dirt intentionally, but only do so in areas where I have a special need or project. for the most part I want vegetation on every inch of every acre, for reasons I'll talk about below.
How much vegetation do you leave?
I like to leave 4 to 6" of growth when I move my pigs to a new area, but the precise amount will vary from farm to farm, from species to species. My cows, for instance, will naturally stop eating and move to a new spot when it's less than 6" tall, if they've got a choice. If you're farming you can develope the skill to measure your grazing and its effects on your land -- remember "management intensive"? This is where your time and attention go, at least initially. You'll give them larger areas and smaller and over time will get a sense of what they can consume and how long it takes them. But the key issue here is NEVER bare dirt in the normal course of grazing.
To be absolutely clear here: I have areas on my farm that are bare dirt; I don't like it, and I work hard not have them, but they do happen. But I am also making NO claim to be doing MIRG, nor am I proposing that other farmers take up that practice. Properly done, it's a lot of work, and honestly, I've got a lot of other chores first; most farmers do.
Here are some pictures of various "pastured pig" operations below. I'd like you to look at the pictures and see if you believe that they're actually examples of "management intesive grazing". there's a comment about each picture at the end of the list.
|Picture courtesy of Wikipedia Commons|
|Picture courtesy of google maps|
|Picture courtesy of SugarMtnfarm over their strong objection|
|Picture courtesy of Polyface farms|
Picture #1 shows what appears to be a permanent feeding station. Note large amounts of bare dirt and minimal vegetation. Most MIRG proponents would say that this area is overgrazed.
Picture #2 shows an aerial view of a farm that appears to be using a free-grazing system. Note what appears to be minimal remaining vegetation and large patches of bare dirt and apparently random animal paths that show no sign of fencing (eg, no straight lines)
Picture #3: Small paddocks are good, but most of them show either bare dirt or minimal vegetation. Most proponents of MIRG would say that the majority of these paddocks are over-grazed.
Picture #4: Fixed, permanent feeding station. Notice permanent animal paths on bare dirt leading to and from this feeding station.
Picture #5: Does this look like rotational grazing?
Picture #6: Unlike cows and other ruminants, pigs do need mud as protection from the sun and insects and overheating. Bare dirt is hated by MIRG proponents, but is needed as part of an outdoor pig operation to allow the pigs to manage their own temperature.