Change in Egg Color ( no change in food )

[HoundsNTrout]

Slightly different angle to a question I see here. I have not changed the food in over a year but fairly suddenly I have one large slight brown egg and I never had that before. Reason I'd like to know what hen its from is I intend to breed my White Leghorns and the NH Red's X my Barred Rocks next year. If it IS a leghorn I want to breed that hen bc it is much larger than the rest.
IS there a method such as food coloring or something in the food I can find out which hen it is? I only have 12 birds now and I am FAIRLY certain on the barred rocks but not the others. Do I have to maybe put them in a crate for a couple days? See who is laying what?
Fairly certain this huge egg is from a Leghorn just bc the barred rocks are still young and lay smaller darker brown eggs.

 

[aart]

IS there a method such as food coloring or something in the food I can find out which hen it is?

You can use food dye in the vent:

 

[Kiki]

Slightly different angle to a question I see here. I have not changed the food in over a year but fairly suddenly I have one large slight brown egg and I never had that before. Reason I'd like to know what hen its from is I intend to breed my White Leghorns and the NH Red's X my Barred Rocks next year. If it IS a leghorn I want to breed that hen bc it is much larger than the rest.
IS there a method such as food coloring or something in the food I can find out which hen it is? I only have 12 birds now and I am FAIRLY certain on the barred rocks but not the others. Do I have to maybe put them in a crate for a couple days? See who is laying what?
Fairly certain this huge egg is from a Leghorn just bc the barred rocks are still young and lay smaller darker brown eggs.

Leghorns lay white eggs.