When to cull chicks

[nursepinch]

First time hatching chicks. 8 out of 8 hatched but 1 had an injury causing bleeding and I had to cull it. They are 2 days old and another one isn't behaving as all the others. It's much smaller, it's not walking, and it doesn't seem to be eating or drinking even when I put it right up to the feed and water. It seems to be alert and in no distress. I donsee any obvious injuries. Should I cull it too or how long should I wait?