I have seven nearly 3-week-old chicks (Orpingtons, Silkie, and Easter Eggers) can I add 1-2 Barred Rocks chicks that are 10 days younger than the group of 7? My current 7 hatched together and I purchased them and brought them home from a larger group at 6 days old.
Adding a Chick to 3 week old chicks
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I would not recommend mixing them, not because of aggression but because the older ones might crowd the food and water and may squash the others (entirely by accident) when they run around. I recommend raising them separately, at least until the smaller ones are as big as the bigger ones. If you have any more questions please ask.
With plenty of brooder space, and two feed and water stations, and all healthy birds, it will most likely work out okay. It's best to set up a screen fence between the groups at first, and not do only one chick, especially if younger. Otherwise, mixing groups into a totally new environment is a good plan. Mary