Is my yearling BCC ready for rats?

[MrCaveman]

So I decided last feeding that I'd give my baby Suri (at least 10 months old, maybe a year) his first rat pup. He took it and after he digested it his feces was a very messy diahrea. Im wondering if its a coincedence or its that his diegestive tract isnt ready for rats. He was having solid dumps while on mice. So should I keep giving him rats or stay with the mice until they're all gone? Or should I alternate 1 rat pup then two mice? or something like that cuz I know young BCC have more sensitive stomachs than young BCI.