Giant cave roaches (Blaberus giganteus) need animal proteins - does not matter if from meat or other foods,
If they do not have them than there is very high mortality during molting from subadults to adults.
One my friend feeds them by rat pups,next by cooked chickens or dry cat,dog or fish food or by meat for cats and dogs or by other meat....
If you will feed them by fruits or vegetables only .... you will have a problem.