I don't see any reason why you can't feed them to your snakes, though if they've been raised solely on mice, they might not take readily to the switch. But you never know. I have a ball python who will eat ANYTHING I give him, but my female ball is really quite fussy, if it isn't a rat or mouse, she won't have anything to do with it.
As for nutritional value, sorry, but I wouldn't know.
I can't see them being too different though.
Just a thought.... if the snakes do refuse to eat the gerbils... try rubbing some really dirty mouse shavings over the gerbils to get the mousie scent on them and try again.
Take care
Annie B. <:3 )~~