I got my first batch of chickens as adults, and they just seemed thin, always eating huge amounts of food without gaining weight, and got to where they weren't laying well. I hadn't really thought about chickens getting worms, but after I read something about it on here it made sense so I had their poop tested (BTW, you don't have to get a stool sample from every chicken... if one chicken has worms, rest assured that ALL of them do). Bingo, they had worms! I don't think you'd need to test them as babies (unless there are symptoms), but probably after age 5-6 months I'd test, and then at least once, and maybe twice, a year after that. Within 2 weeks of worming a chicken that has worms, you'll likely see increased egg laying, lowered food consumption, and what just seems like a happier bird. It just can't be a good thing to have a belly full of worms! I do remember reading a study that said that nearly 100% of chickens age 1 year or older had worms (can't find the study now unfortunately). As a guide,a laying hen should do well on about 1/4 pound of crumbles (or pellets) per day, any big variance from that needs to be explained. We do have a resident expert here on worming, dawg53, if you have any questions he's the go-to guy.
