Yorkshires are one of the largest breeds. If you're shooting for a middle-sized pig you might want to consider Hampshire or Berkshire. Most of our Yorkshire cross sows are around 600 to 800 lbs with a couple over 900 lbs. We just took two small ones to the butcher who were 450 lbs. Good sausage sows. The big boars are a lot larger. I think that your choice of the sow being the larger Yorkshire and the boar being the smaller pig, the Pot Belly, is wise. It would be a shame to have a small breed gilt try to farrow a littler of huge farm size piglets. Humans are bad enough on the way out.
Our gilts tend to take their first breeding at about eight months. We tend to wean at four to six weeks. Since we keep the pigs as two herds with the boars in them the sows rebreed as soon as they are ready. For most of them this is around a week after weaning give or take some days. Some sows are much more anxious to get back in the action - they'll even jump a fence to get to the boars if I fence them and then they carry while nursing.
As to the eating grass, our big farm pigs thrive on pasture/hay depending on the season (warm/winter). We supplement that with dairy, mostly in the form of whey from cheese and butter making. Free fed they eat about 90% pasture/hay and 7% dairy by dry matter weight plus about 3% other things such as pumpkins, apples, beets, turnips, etc.
One observation is that the larger pigs graze better. They have bigger jaws, teeth and their bigger gut probably helps too. Older experienced sows are also better mothers in general - in part because those who aren't get culled.
The flavor of ours is superb, according to our customers. We sell weekly to chefs, white table cloth restaurants, health food stores, coops and to individuals. Me, I'm not so sure I can discern finely - meat is meat is meat. The fat on ours does taste sweeter than store meat. I think that is from the dairy. The color is richer. I think that is from walking around the pasture. I like knowing it was naturally raised and not full of chemicals. Mostly at the end of a hard work day I am more interested in filling my belly to get the energy for the next day. Functionalism. I just am lucky and get to eat all the pastured pork I want, so long as I'm willing to eat low on the hog - the high on the hog stuff all sells every week. I guess we're like the shoemaker's children.
Shoeless and happy.
Sugar Mountain Farm
Pastured Pigs, Sheep & Kids
in the mountains of Vermont
Read about our on-farm butcher shop project: