There are so many variations that happen. I don't even notice or try to keep track. We collect, we eat/sell.

That white spec....is chicken egg too...

For those who PM'd the OP………….maybe the rest of us wanted to learn something, too!

I think the key thing is that your hens are laying eggs; therefore, it isn't likely that you have a feeding defeciency or lack of water. Sometime people forget that when hens lay eggs they are reproducing, they aren't laying eggs so we can have our chorizo and egg taco or our egg McMuffin, I know that may sound funny but sometimes people get so detached they don't remember that a hen laying an egg is reproducing. It is an innate behavior for them to stop laying in stressful situations such as a severly deficient diet or prolonged lack of water. Given that your hens are laying fine, I am sure you don't have an issue there. The pigment that makes egg shells brown is ooporhyrin or some more modern studies list it as protoporphyrin IX. The pigmentation on egg shells can be influenced by a number of parameters such as housing system (cage-free, pasture raised, traditional caged system, etc), age of the hen, breed, diet, stressors and diseases such as infectious bronchitis. In your case Black Australorps and Barred Plymouth Rocks are both light brown egg layers (I suspect the egg in the picture came from one of these) whereas Rhode Island Reds usually lay slightly to much darker brown eggs. I don't think you have anything to worry about, I am certain you are feeding a commercially availalbe layer feed, so it is more than adequately balanced and exactly what they need. Enjoy the hens!! The days will soon get shorter and I am sure you are aware that length of photoperiod affects laying, so you may need to "extend the day" a bit with lights. For what it is worth, I have seen a ton of eggs that look just like the one in your picture.

I read the Outdoor board every few days and I always enjoy it but I don't post very often. I studied Animal Science and Poultry Science (those two departments did not like each other when I was there, long ago, haha) so your question caught my attention. Because of my job I go onto commercial poultry operations often so I cannot have birds at home for biosecurity reasons, so I always enjoy the backyard poultry questions on the outdoor board. I think there are other poultry scientists on the board if memory serves. Gig'em

References:
Donald D. Bell and Willieam D. Weaver, Jr, Commercial Chicken Meat and Egg Production, 5th Edition

Samiullah, S., J.R. Roberts, and K. Chousalkar, 2015/ Eggshell color in brown-egg laying hens-a review. Poultry Science Oct; 94(10):2566-75

How is the integrity of the eggshell? Is it strong or do they break easy?

I'm not a poultry "expert" but on the feed (we manufacture livestock feed) if the eggshells are brittle, you might try a higher protein layer ration and also put out some oyster shell. The color to me is likely just what that bird puts out as egg color in different breeds and different diets can vary significantly. Some poultry science (or vet) person can hopefully chime in if there is something wrong with the bird(s).

Thank you tree... I will remember this.

@ Build It... SSS.

Chicken math is a thing for sure. We try to average 10 birds. When I get down to between 6 to 8 birds, I order enough to take me back up to 12 to 14. My chickens are averaging somewhere between 6 to 12 months before nature takes them out. Coyotes, foxes, racoons, hawks and I think a neighbors dog make sure I have fresh young hens all the time. Frustrating when you get them old enough to finally lay eggs and something takes out 2 to 5 of them in a single day.

I've got a 3 year old hen who is too tough to die and an older rooster that must push the hens towards the danger to save himself, because he has outlived 2 or 3 rounds of chick purchases.

Chicken math doesn't work out financially. We spend way more on them than we ever save by not buying store eggs, but it's a fun hobby and something for me to have my kids do instead of technology.