Chicken mass vs egg mass- consistent?

[Fishkeeper]

Do all sizes of chicken tend to lay roughly the same size of egg, proportionately? That is, does a small chicken lay an egg that's the same percentage of its mass as a large chicken lays?

 

[sylviethecochin]

Do all sizes of chicken tend to lay roughly the same size of egg, proportionately? That is, does a small chicken lay an egg that's the same percentage of its mass as a large chicken lays?

Nope. Example: Standard Cochins vs Leghorns.

 

[ChocolateMouse]

Not at all. There's plenty of big chickens that lay smaller eggs. Leghorns and norwegian jaerhons are great examples of very small birds that lay a proportionally very large eggs.

In fact, an overweight chicken with too much fat can actually inhibit laying well.

 

[ChocolateMouse]

Consider these two sources:
http://www.sagehenfarmlodi.com/chooks/chooks.html
https://www.backyardchickens.com/threads/breed-info-on-norwegian-jærhøns-jaerhons-jaerhon.308555/

The first says a 4.1kg brahma lays a 55g egg.
The first also says a 3kg barnevelder lays a 60g egg.
The second says a 1.75kg jaerhon hen lays a 55g egg.

So, obviously there's not a strong correlation there. Which makes sense given that some bird can lay eggs that are a massive percentage of their own size, such as kiwis and some lay comparatively small eggs.