I leave raw out for Jasper and Puddles to munch on all night. He eats most as soon as he gets it, Puddles gets the licked overs.
His poops were not affected at all by the raw, except they are smaller now
.
As for the hard membranes, they seem to move the meat to chew with their back teeth, if it seems to be too hard, they spit it out beside their dish.