I use a small handful mixed well in with two armfuls of farm hay and two piches of dried herbage for Pumpkin.
Hay is better, the grass is a an extra treat that can added for foraging fun. I think of the kiln dried grass is like handing over the nice biscuit tin to Pumpkin - he still needs to eat far more hay and if he gets is nose into a bag of kiln dried grass he pigs out.
Ziggy Pig [Gpig] just chuffs the stuff down with his hay but Piggies have slightly less temperamental digestive tracts.