Build a farm where you captured the boar. It doesn't have to be huge unless you want it to be. Build a lodge with a couple chests and a portal, a couple farm plots to grow food for your boars, make a barn, feed your 2 star and your 0 star, when the 2 star makes a piggie it will be a 2 star and when the 0 star makes a piggie it will be a zero star. When you get several 2 star boars cull the 0 stars.

Portal to your farm and feed your boars, while you are there pick your food for the boars and replant, by the time you are done all of your boars should have produced piggies. You can then leave and the piggies will grow while you are gone.