There are SEVERAL posts on here on training dogs to leave chickens alone, check them out.
My suggestion would be, to put pups on leashes anytime they're outside & anytime they show the SLIGHTEST interest in chicks, scold pups (I would also only do one pup at a time) or just say NO or leave it or whatever word(s) you use, then remove pup until it calms down. Keep doing this until pup gets message, it has to TOTALLY ignore chicks or chickens (this is how we trained our dogs on the farm), of course, it all depends on dog, some have extensive "PREY DRIVE" & no matter what you do, can NEVER, EVER be trusted around chicks or chickens, usually though, with patience & LOTS & LOTS of this training, they'll get the message. If not, they'll just have to be kept completely separated at all times & NEVER left together unsupervised.
My suggestion would be, to put pups on leashes anytime they're outside & anytime they show the SLIGHTEST interest in chicks, scold pups (I would also only do one pup at a time) or just say NO or leave it or whatever word(s) you use, then remove pup until it calms down. Keep doing this until pup gets message, it has to TOTALLY ignore chicks or chickens (this is how we trained our dogs on the farm), of course, it all depends on dog, some have extensive "PREY DRIVE" & no matter what you do, can NEVER, EVER be trusted around chicks or chickens, usually though, with patience & LOTS & LOTS of this training, they'll get the message. If not, they'll just have to be kept completely separated at all times & NEVER left together unsupervised.
