It would be a good idea to leave the back blank so that the person handing it out can jot a note there: BYC username, contact info, etc. I miss having a biz card that's blank on the back for this very reason!
On a side note, WA State (or at least my county) forbids sales of individual chicks. You've got to buy them 6 at a time. I think it's to prevent chicks being sold at Easter, though it's a pain if you just want a few for a backyard flock.