I am looking at the feasibility of raising pasture hogs in my neck of the woods. Space is no issue at all. I am simply wondering how many hogs/ acre of good pasture, how well they will gain on grass/forbs/brush, and if they would need much supplemental feeding. Good feed grains is no issue either, as I grow them myself, and always have lots available. I can buy 50-60 pounders in the spring, what type of timeline to get them to 250 pounds on mostly pasture?
General rule of thumb that I've heard here in WI is a sow and litter per acre, or about 10-20feeder pigs. Maybe even more if you have real good alfalfa. Feeder pigs will grow a little slower on pasture vs. straight grain, cuz they are not ruminants. Their digestive tract is not as long, and they can't extract as much nutrition from it as a mature sow or a cow. But it will fill them and they eat less grain per day. This is not necessarily a bad thing, and makes very flavorful pork. If you have a self feeder filled with a mix of corn and soy or other pig grains and put that out with your pastured pigs, you can get a very good sized hog in about 4-5 months. The grain mix (with minerals) ensures they get proper amino acids, vitamins, protein, etc.
In possibly the same area as Welshmom, the hog house on the homestead was set up with 12 farrowing stalls and the permanent hog pasture was exactly 20 acres of mostly hardwoods. The hogs there were Durocs and always 12 brood sows. In fall of the year, grain and whey would remain so long in the troughs that it would almost ferment because the hogs were eating acorns. (That was in Wyoming Township, Sneed Creek to be precise.)
As a very rough rule of thumb I figure 10 pigs per acre using the managed rotational grazing. We feed pasture replaced with hay in the winter and dairy (mostly whey) and this is almost all of their diet. We use the winter paddocks to grow pumpkins, turnips, etc and we frost seed our pastures with legumes (clovers, etc), rape, kale and other things to increase the protein levels. This has worked very well for us. We recently expanded our pastures to about 70 acres - a little of that is tree covered which makes for some nice variety and some is brushy. We had about 300 pigs on that this past year. The pig/acre ratio goes up and down in uneven bumps - don't expect linear graphs as things change in jumps.
I know this can be a hot topic so this is just my opinion from my own experience. We started with 5 piglets that were a cross between a duroc sow & a berkshire boar. We put them on pasture in August at about 10-12 weeks old, thinking we could feed them mainly pasture & supplement with kitchen scraps & a bit of bagged feed. By the end of the fall & moving into winter we realized they were just not going to make weight the way we were doing it anytime soon. When we first started someone told me they would never make weight on pasture alone- not enough protein. But, being a newbie with no pig raising experience & lots of great ideas of my own I just didn't believe them. I figured we'd just let them take as long as they needed and they'd make weight eventually. By the end of November our pasture was no longer providing anything green & we were feeding hay, and lots of bagged feed. By the time they were butchered at the end of March the biggest one had a hanging weight of 110lbs. The meat was very tasty, but those were the smallest pork chops I had ever seen. Now we raise on pasture & feed brewery grain and kitchen scraps from a local school. It still takes us about 10 months to get close to 200 lbs hanging weight. So in regards to the original question- "how long to get to 250lbs on mostly pasture?" This is my third year and I haven't done it yet.
Barefoots experience is what I've heard over and over again about people raising standard farm pigs on pasture. If you don't have a substantial source of feed in addition to whatever they can scrounge you'll have very small pigs.
I stock at 6 pigs per acre on good river-bottom land, provide tons of fresh produce and free-choice standard pig feed, and with that combination I'm able to get pigs to market in an appropriate timeframe. They do eat grass and various other forage items (earthworms, blackberry roots, small bushes), but they eat their feed as well.
There's a lot of talk about raising pigs on pasture alone, but I have yet to find anyone whos done it. The last fellow who claimed it I offered $10,000 to to raise his pigs per his claims. He declined.
Hogs really can't get much from the pasture until they are four months old or older. Mature hogs can be kept in maintenance condition on pasture alone but piglets need extra protein.
You also need to have a breed that has the metabolism for pasture and the pasture has to be at least 30% legumes or other protein source. Grass alone will not do it. And the grass needs to be kept short; hogs don't eat it when it gets hard stems.
If you have a good pasture it will take about nine months or more without supplemental feed. If you provide supplemental feed you can do it in less time.
We get our GOS to 250 lbs in nine months and our Large Blacks take a month longer. Our pasture has been mixed grass and 40% clover. I'm going to be planting alfalfa and/or rape this year and we'll see if they grow faster on that. The clover tends to die out in the heat of summer.
We also finish in the woods on acorns, walnuts and whatever else is there as well as alfalfa hay.
Stocking rate is 10 hogs per acre, rotating every three weeks or so.
Pasture hogs will have relatively lean meat. If you want lard you need to load them with corn.
Heritage, I think that the OP is looking for how many acres total to produce how many hogs. How often do you rotate the hogs onto a new pasture, and how much rest do you give between rotations?
at 4 weeks rotation, and with a rest period of 6 months, you'd need at least 6 acres to produce 10 hogs. Most folks forget the rest period that's part of rotational grazing. Otherwise you're continuous grazing, and that's not the same thing at all.