If you toss in enough clippings that they can readily consume, it should be fine.
But you must also not spray the yard with any chemicals what so ever, no organic, no nothing.
Once the grass starts to ferment, it can become dangerous. Most commonly to horses, but still possible to other grass grazers.
So if they can eat a 5# pile of freshly chopped, scooped and dumped grass in about 2hrs, that's ok. Mine tend to abandon any grass that becomes dry or when they just get too full. Best to feed them, or better yet, to mow late in the day. That way, they will eat far more of it and at a faster pace. So aim for twilight.
You can also leave the mowed grass for 2 days of full Sun to dry. Then you have home made hay you can use for nests, bedding or feed! =D
Just don't try it if it's going to rain!
__________ Thu Jul 19, 2012 6:13 pm __________
Also, fluff or 'wash' clippings in a bucket of cold water. This will get any 'mulled' grass off and allow better air circulation.