I don't know where you are located, but the quality of the grass with us has really gone over the past fortnight- it's been too dry. So, now our goats are back to eating lots of hay again. They really didn't look much for hay for six weeks from the middle of June.
I would give them less, or try putting some straw into the feeder. Straw will provide the roughage, but might not be as appealing as hay.
Beth