Kune kunes are grazing pigs, so excellent that they'll have grazing. It can be worth splitting it off into small areas and moving them round a section at a time to allow the grass to grow back in between. They love veg, if you can get some waste or by the tonne from local greengrocer or farmer, that's fab. Any garden waste can be fed, but remember it is ILLEGAL to feed waste from your kitchen in case of any meat contamination that could spread diseases like foot and mouth.
The rough rule is for every 4 lb veg you feed, you can cut pig food back by 1lb.
Roughly kunes will need 1lb a day for a non productive pig, ie not growing, pregnant or lactating.
When our sows are pregnant or lactating, I increase the feed gradually, so at birth theyre roughly double normal rations. Then once they have piglets, I increase based on keeping the sow's condition the same. As verdifish says, our first time gilt with 6 stonking 7 week old piglets is on 4 scoops twice a day, 4 x normal as she is milking heavily and tending towards too thin. The other sow has 8 6 week old piglets and gets 2-3 x rations as she is holding her weight more.
The amount of pig nuts can be tricky to judge, but if you had a piggy friend they may be able to show you how to estimate how fat or thin the sow is. When the piglets are weaned, they will likely not need a lot of hard feed, and the lower protein kune kune or pot bellied pig feeds can help stop them getting fat.
Anyway, enjoy them, kune piglets are wonderful!