You are right once the membrane is broken the duckling would not depend on gas exchange through it. The op did not seem sure if the duckling had internally pipped though. Until then, it was dependent on it. Now that it has externally pipped it wouldn’t matter.Just wondering but what do you mean they breath through the membrane? From what I’ve seen and heard they break a hole in the membrane so they can breath the air cell and then once they externally pip, breath through the hole. I’ve seen many people use Vaseline and it is a pretty common practice I’ve never had any issues with personally
If that membrane isn’t kept moist it can cause shrink wrapping