What mineral supplements do pigs need

I am about to get pigs again after a break of 6 years and last time we just fed organic pelleted feed. This time they will be in a 1.5 acre field of pasture and gorse and I'm hoping to feed fewer pellets. They will get some goats milk and barley plus some pellets. Will I need to give supplemental minerals?

1) Get your soil tested to find out how complete it is. Typically selenium and iron are the highest concerns.

2) Consider supplementing with kelp. It is available certified organic if you want. See: http://www.noamkelp.com

Our soils are complete according to the soil tests but I have discovered over the years that I get an increase of one piglet per year if I also feed kelp. It doesn't take much, about a quarter ounce per hundred weight per day. See:

http://sugarmtnfarm.com/2012/03/24/mineral-deficiencies/