Well, how is slaughtering chickens ethical?

For every egg-laying chicken out there, a male chicken is slaughtered, and both egg-laying and dairy milking harm the animals (for instance, compare avg. life span of a dairy cow with their natural life-span).

There's also the factor of number of animals killed - One lamb feeds a lot more people than one chicken, yet both are living animals capable of pain and suffering.

That's not to say that either is particularly ethical, but (as a vegan), I don't think you can easily say that eating eggs is intrinsically more ethical than eating meat.