Mine exploded when I first started too. Some feeds will expand more than others and it probably also has something to do with environmental conditions. Glad your birds are liking it so well already. Mine have been on it since 2 weeks old, they are just over a year now and do not have any access to dry.
I won't be feeding out the dry once this initial fermentation is finished and never intended to give the mash but I was out of storage options and wasn't going to let it go to waste. It's good to know I'm not alone in creating feed explosions! Lol