We pasture pigs.
We have about 300 of them.
We do managed intensive rotational grazing with them, just like sheep, goats, cattle, etc.
Our pigs graze and do not root very much.
When a pasture is brushy and new they may root more because there are interesting tubers, grubs and such they're getting. Once the pasture is good grazing they graze more and root little.
Factors that may increase rooting are:
Lack of forage;
Brush;
Tubers;
Grubs;
Wet soil;
Clay soil;
Over grazing.
You may need to use smaller paddocks and rotate more frequently. This is the same as with sheep and other grazing animals. If they're mobbing and area it gets mucky, compacts the soil, over grazes the forage, etc.
In the cold months we feed hay to replace the pasture.
In addition to the pasture/hay we also feed unlimited dairy which is primarily whey. This provides lysine, a limiting protein, and some additional calories. We also seasonally have pumpkins, apples, nuts, kale, beets, etc as well as a little spent barley from a local brew pub and dated bread for training treats to help with weekly loading of pigs to market.
Seventeen acres should be plenty of land properly managed. We have about 300 pigs grazing on about 70 to 60 acres which is more than they actually need - I just recently made a large bump up in our pasture area. We graze our sheep, pigs, ducks and geese together - they are excellent co-grazers.
These posts might help you:
http://flashweb.com/animals/pigs http://sugarmtnfarm.com/blog/2007/10/how-much-land-per-pig.html http://sugarmtnfarm.com/blog/2009/09/happy-as-pigs-in-clover.html Good luck with your pigs. They're hardy and versatile animals that are an excellent part of a farmstead.
Cheers
-Walter
Sugar Mountain Farm
Pastured Pigs, Sheep & Kids
in the mountains of Vermont
Read about our on-farm butcher shop project:
http://SugarMtnFarm.com/butchershop http://SugarMtnFarm.com/csa