you can dice the gerbil. but him in a blender. whatever.
when you wanna feed, take out a f/t mouse. and defrost a cube of gerbil or a tspoon full of gerbil paste. then rub the cube all over the thawed mouse, or even better, rub a little gerbil paste on it.
im sure thatd work. gruesome as it may be :p
cost effecient too , you may even get 20 feedings :p