They are a pretty well known group in the German speaking part of Europe.
Their enclosures are incredible - absolutely huge and filled with enrichment, fully enclosed with sun and rain protection, and additional indoor space. They are mostly known for their successful keeping of very large groups of piggies (including males) together.
The grass is pretty standard for rural areas, and I think they not only have farm access but proper grass cutting tools (a scythe which are still commonly used here) and a large barrow to transport it. I believe they also have volunteers who turn up with grass for them too.
To be honest if time wasn't an issue I could harvest similar amounts myself a couple of times a week during the peak growing seson in a good year. If I could use a scythe of course - a local farmer tried to show me once (he was fascinated by my cloth bag and scissors collection method) and it is MUCH harder than it looks - it's all about angles and I don't think I managed to cut a single blade!
@Wiebke probably knows more about them, as I know she maintains a close relationship with many of the German rescue and piggy groups.