We purchased 5 new chicks. They are about 3 weeks old.. one has not grown. We named her Peanut. She did have a bit of pasty butt at first but has since cleared up. She eats, drinks and poos but has not grown. Any advice??
All you can do is ensure they're eating and drinking well and hope they grow eventually. Vitamin supplements may help if there's some sort of vitamin issue, such as nutridrench. I usually give it to struggling/not growing chicks once per day.
Sometimes runts do eventually grow out, or remain small and healthy. Sometimes they die eventually if there's something internally wrong.