What causes egg shell color change?

[redsix]

We have some of our Australorps that just started laying about 3 weeks ago. The eggs of the one hen keep getting lighter and lighter in color. She laid one this week that was almost white. What causes the change in the brown color?

 

[ChickenCanoe]

Lots of things can affect shell color. Stress, age, drugs, and disease among them. Most breeds produce more pigment early in the seasonal cycle. Nutrition may have something to do with it. It is unusual for it to happen so quickly.
There's little research on the chemicals that make up those pigments. Protoporphyrin is thought to be the primary pigment in brown eggs but I'm convinced that there are many others in dark layers shells like those of Marans and Penedesencas.

http://edis.ifas.ufl.edu/vm047

http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=617944

http://www.communitychickens.com/all-about-egg-color/

http://www.ncbi.nlm.nih.gov/pubmed/16553287

 

[Ridgerunner]

Canoe, here’s another article you might want to add to your list. You’ll see that there are some conflicts with some of the other articles. For example, the blue in a blue/green egg is not made from bile. It’s made from recycling used red blood cells using the same process in the uterus that makes bile blue.

http://www.maranschickenclubusa.com/files/eggreview.pdf

Redsix, how consistent has this change been? It’s pretty normal for brown eggs to gradually get lighter as the chicken lays. Pullets normally start out laying tiny eggs but the eggs get larger the longer they lay. Often the shell gland makes a set amount of pigment to color the egg. As the egg gets larger, that set amount of pigment gets spread out more. That makes it lighter. So if the eggs are getting bigger this could explain a gradual change.

I’ve noticed with mine that the longer a hen lays after the molt the lighter the eggs get, even if they are not getting bigger. I’m not sure why. The brown color comes from recycled worn-out red blood cells so the raw material is always there. It’s as if some catalyst is getting used up as the season goes along. When the hen molts and quits laying, she seems to store up more of whatever this material is. When a pullet starts laying and when an older hen starts laying after a molt is when the eggs will be darkest.

Since with most hens the brown is put on at the end of the time in the shell gland, if something happens to stress the hen she may lay the egg early, before all that brown is added. That’s a big reason for you to suddenly get an all-white egg from brown egg layers, then they go back to laying brown eggs. It’s not a disease, something scared her. And that could be anything.

As Canoe said, a lot of different things can cause an egg shell to change color. As long as the chickens are not acting sick I would not worry. It’s probably not a big deal.

 

[redsix]

Thanks for all the replys above. The egg color seems to be getting darker again. Just got the one egg that was really white. I think it must have been caused by stress? The only diet change is the addition of millet. I recently started feeding them a little bit of the millet that I grew. Couldn't get them to pick it off the head inside the coop. Stuck the stalk heads through the run fence and they have been fighting over it. Go figure.

 

[azygous]

Interesting you should bring up this topic. I have a five-month old Silver Cuckoo Marans that just began laying. Her eggs have been a very dark reddish brown. However, today she laid a light tan egg! I know it was hers because I saw her come off the nest.

The flock has been on Corid for a few days. From what you say, Canoe, would this account for the drastic color change?

 

[aart]

Had a wellie mix pullet lay a couple very oddly speckled eggs 2-3 days in a row, then back to her normal darker reddish brown.
Glitch in the spray booth is what I figured.

 

[spaceylocust]

I'm having the same problem and strongly suspect it is a nutritional deficiency. Finding research or anything to substantiate that is proving difficult! Going through these articles really hasn't helped, as interesting as they are.

Since the brown color is determined by red blood cells (basically, I think), do you think it would be an iron deficiency? In the past, I've added molasses to my feed mix to give an iron boost but didn't really pay attention to the egg color afterwards.

So, I'll do the scientific experiment and add molasses and see if it makes any difference. As full disclosure, I'm now making my own feed mix of organic whole grains (several types), fish meal, ground seaweed, and a vitamin/mineral mix to make sure everyone gets what they need. And this mix is fermented--they LOVE this. They occasionally get a handful of sunflower seeds and freeze dried black soldier fly grubs.