Large Blacks are great
Gentle, unassuming and don't cause any bother
They're slower growing as Sally says, but you can't rush them as over feeding just leads to excess fat (like all traditional breeds) They do graze a bit as adults, youngsters will still rotivate and we had a sow who went elsewhere and ploughed everything, despite being fine here
I think the type of ground and amount of land might make a difference (she had more space and rougher grazing here) but they can just take a notion into their heads sometimes and have a root about - I wouldn't count any forage they get as having any major nutritional value or as a replacement for hard feeding though.
I love mine, they're second only to kunekune in my eyes (and I'm besotted with them
) don't let their size put you off - they're so docile (mainly because they can't see anything
) real gentle giants
The Large Black breeders club is a great source of stock for sale (there's also a facebook page)
http://blackpig.electriclemonmp3.co.uk/herds/ or drop Janice the secretary a message. It's worth contacting breeders in late August to enquire and put your name down on their waiting lists for the January litters, as with all the rare breeds they can sometimes be tricky to track down, especially as they're normally reserved as soon as they're born.
HTH