What cross is this?

[CluckkyKrista]

And yep - it was a double yoker So maybe they won’t continue to be so big when she gets going. Today was another 70g-er though

Curiosity- are double yokers ever the result of surplus fat in the diet? Seems like a good way to expel extra…

 

[NatJ]

And yep - it was a double yoker So maybe they won’t continue to be so big when she gets going. Today was another 70g-er though

Curiosity- are double yokers ever the result of surplus fat in the diet? Seems like a good way to expel extra…

Double yolkers are a result of glitches in the reproductive system: her body releases two egg yolks instead of one that day (similar to the mechanism that causes twins or triplets in humans and other mammals.)

They are more common with new layers and also with hens that are getting old.

Here is an article that talks about a bunch of odd things that can happen with eggs:
https://www.backyardchickens.com/articles/common-egg-quality-problems.65923/

And her is an article on a different site that talks more about double yolk eggs specifically:
https://www.cacklehatchery.com/what-causes-double-yolk-eggs/

That article also has a link to a study from 2012 showing that double yolk eggs are a certain amount heritable (you can selectively breed for hens that lay more or less of them.) The study also found that double yolk eggs were associated with hens who have a higher bodyweight, although I don't see it mention whether that means fat hens or hens that are just plain bigger. A writeup of the study is here:
https://www.sciencedirect.com/science/article/pii/S0032579119402460

I also found a study from 1990 that talked about chickens who were selected to lay multiple yolk eggs, and it said "Double and multiple-yolk eggs are a manifestation of an irregular ovulatory pattern." https://pubmed.ncbi.nlm.nih.gov/2374135/

As regards surplus fat in the diet: hens who get more energy (calories) than they need will become fat, depositing it especially in their abdomen. That happens regardless of whether the extra calories are fat or carbohydrate. Broody hens don't eat much, and they do partly live on that fat while they are broody, so broodiness is definitely one way for a hen to lose weight. If anyone has studied whether level of fat has a correlation to broodiness, I haven't found it yet, but I think it would be interesting to know. At a very basic level it looks like there may be a correlation: Leghorns are well know for not going broody very often, and they also tend to not accumulate as much fat as the dual-purpose breeds and the meat breeds, both of which tend to go broody at higher rates than Leghorns. But on the other hand, Silkies are known for going broody, and I haven't heard of them having any extra tendency to fat, so it might just be a coincidence of which traits ended up in which breeds.