A Cause of Odd Eggs

It’s very difficult, as the keeper of a small and varied backyard flock, to make an accurate diagnosis about most health issues. Hen standing like a penguin? It could be cancer. Or she could be constipated. Rattly breath? Respiratory disease (and there are many) or ascites, or peritonitis. Or she swallowed a bit of straw wrong and will be fine by evening. If you’re looking for answers and go to an on-line poultry forum you’ll get a lot of misinformation, rehashing of Damerow’s books, and maybe some good tips, if you can sort the useful from the bad. There are plenty of blogs out there long on advice, but short on actual experience with the diseases they’re talking about.

When I’m faced with an issue with my girls that I need to know more about, I turn to Veterinary manuals, scientific journals, poultry industry research and fact sheets put on-line by Extension Departments (United States and Canadian agriculture colleges have these outreach offices to help farmers). I’ve gleaned much enlightening information from these sources, but it is not always applicable for my situation because all of the research is done on young, commercial flocks, and the protocols and advice given are for farmers, not a suburban chicken keeper who dotes on her old hens. As one extension fact sheet stated, layers are usually kept for 52 weeks. My Gems are 110 weeks old. Twinkydink is 416 weeks old. To poultry scientists, these birds don’t exist.

When researching what might be going on that the Gems are laying eggs with ridges, crackles, and rough surfaces, I came across photos of eggs that exactly matched what I’m finding in the nesting boxes. This photo from Cornell (scroll to photo # 5 of 8) matches Florence’s egg. These photos match the other eggs that I’ve been blogging about. The culprit appears to be infectious bronchitis (iB). On a production farm, with pullets of one breed, crowded by the tens of thousands inside buildings, this can be devastating. Birds will exhibit severe respiratory symptoms. Egg production will drop to near to nothing for up to four weeks. Eggs that are laid will be large and thin-shelled. iB is caused by a virus. There is no treatment other than time. Eventually the symptoms will pass, normal eggs will be laid, and the farmer will have to add up the financial losses. At 52 weeks all of those layers will be slaughtered, the housing disinfected, and the farmer will hope not to see this in the next group.

My Gems might have iB, but they never showed respiratory symptoms, egg production has dropped by only 10 % and less than half of the flock are laying odd eggs. Is this because older chickens some have immunity? Pullets on production farms are under a huge amount of stress. Perhaps that’s why entire flocks on factory farms succumb so severely. I have no way of knowing.

Or, perhaps my hens are carriers of another virus, one that causes Egg Drop Syndrome. Unlike iB, the affected flocks don’t show respiratory symptoms. They do lay eggs with shells the texture of sandpaper. Only one of my hens does that. Wild birds carry this virus, so perhaps that’s how it got a foothold here. Again, there’s no cure other than time. Since these viruses only affect birds (iB afflicts only chickens) the eggs are safe to eat.

If I were a commercial farmer, I’d follow the recommendations and slaughter all of the birds, disinfect, and begin anew. I’d also pay for lab tests to accurately identify the pathogen. But, I am not a farmer. I’m not even trying to have a sustainable homestead. As someone who keeps old chickens, I already accept the fact of life that egg production peaks at the first year, and goes down from there. I’m fine with a few less eggs because of this virus. I am not going to keep my chickens indoors away from all wild birds and possibly infected soil. I like to think that the healthy, less stressful housing, with fresh air and sunshine that I have here offsets the downside of possible exposure to pathogens. Since viruses lurk in damp and dust, I am obsessive about keeping my coop clean and dry.

I am concerned about the thin-shelled eggs caused by the virus. Thin eggs are already a problem with my older hens, simply because as chickens age they are less able to metabolize calcium for egg production. Fragile shells can lead to laying issues, including breakage and infection in the hen, impaction, and the bad habit of egg eating. I will have to be especially vigilant about collecting eggs frequently, watching for laying discomfort, and feeding a balanced diet to promote the sturdiest eggs possible.

I have a feeling that these viruses are prevalent in home flocks, as one of the most emailed questions that I get is about odd eggs. I think that most of us with older flocks live with some level of infection. The viruses do not survive long in fresh air, but still, I think about biosecurity. I am already careful not to wear barn shoes and jackets when visiting friends with flocks, and I ask them to do the same when coming here.

So, once again, I have to fall back on common sense and experience. I think that I’ve struck the right balance here, but I’m always learning. I’ll keep you updated.



  1. On June 12 there was a wild bird in the little barn swinging on the feeder. I made a post that day under “Chicken Keeping workshop scheduled!”. I do not know if you saw it or not. I wondered, if a bird can get into the little barn might something else slide in what ever way the birds are getting in.

    • The wild birds that you see fly in and out of the hens’ pens and coops are usually house sparrows, though I’ve seen others. No birds larger than that can get it, although when the chickens free-range they’re certainly exposed to any number of wild birds. We don’t have wildfowl on the property, which are often the culprits for spreading disease.

      • There are sparrows in our Costco store and in Home Depot and Lowes Home Improvement. We have canadian geese all over town and seagulls who hang out at the garbage dump and fastfood places. I tried to feed the birds this fall but they notified everybody they knew on the Eastern seaboard to come on down to my feeders. I couldn’t afford to keep it up!

  2. Hi Terry,

    My red star is the only hen I have that lays every day and after about 6 months of laying, half of her eggs started coming out like the ones you described. They were a pale peach color instead of brown, rough like sandpaper and thin shelled. There were a couple of times when she’s had trouble passing them and we’ve had to help her. Like you, I started researching and came up with the same list of diseases you mentioned in your blog. All of my hens get layer’s feed and free choice calcium, so I never considered calcium deficiency as a culprit. Everything I’ve read says that the hen will consume the calcium she needs, but I no longer think this is true. I have never seen any of my girls eat the crushed oyster shell. I even marked a line to monitor the level, and after a few months, it hadn’t changed at all. Even if the level had changed, there was no way to know who was eating it and who wasn’t. So I started giving my girls a couple of spoon fulls of yogurt or cottage cheese sprinkled liberally with crushed oyster shell 3 times a week, and my red star’s egg problems cleared up completely. They love cottage cheese and yogurt treats and don’t even notice the oyster shells sprinkled on top. I’ve had nice, smooth, medium brown colored, extra large eggs for a full month now. Hope this is helpful to you and others.

    • Red Stars are egg-making hybrids. They do tend to wear out and often are the first in the flock to die. You’ll find that their eggs thin after time, even without disease and even on a perfect diet. Although yogurt or cottage cheese can give their systems a boost, I wouldn’t feed it, with the added oyster shell, on an on-going basis as I’ve read studies that show problems associated with that calcium and protein high diet. My chickens will ignore the oyster shell, and then go through a bout of eating it. It will look like they’re not touching it, and then I’ll notice that it’s gone.

  3. I save my eggshells, and have people who I give eggs to save the shells for me. I crush them, bake them, and give back to the girls. They do eat the shells, but I have occasionally had to substitute oyster shell which they do not eat.

  4. Hi Terry,

    I’ve been to other blogs, sites, hatcheries and links to governmental agencies. Your blog seems to be the most accurate, user-friendly, and closest to what we’re doing here. The entertainment and beauty of your pics are icing on the cake. Thanks for sharing this information. I’ve pinned it for future reference. I liked Deni’s post too. Thanks for helping Terry and Deni.

    • P.S.- The biggest draw to your site was, of course, Hencam. Love it.

  5. Really liked this article, however just love all the information here and the Hencams are well worth a visit, any information on how to set one up like this…???

    • The cam setup is explained in a FAQ. It’s complicated and time-consuming to maintain, and expensive to run! Which is why I’m so appreciative of everyone who buys my books, and treats me to coffee. That helps me to justify what we put into it. (And when I hear that my writing has helped you and your animals in some way, that really keeps me going!)

  6. I just have one born that lays sandpapery eggs but this is her third laying season and she is still laying 4 eggs a week, she is a Wynadotte. Do the eggs get larger as the hen ages. Ill take a pic and email it.to you

  7. Hi there I went to the website and looked at the eggs…..brought up some questions.

    New Castle Disease and infectious bronchitis….were the causes of the eggs shell issues on that website.

    Can we get sick by eating these eggs?

    Do you vacinate your Hens?

    • Newcastle shows other symptoms, so I eliminated that. These are specifically avian viruses, people are unaffected, so you can eat the eggs. Vaccination isn’t available for backyard flocks, and isn’t effective for the sort of life that we give our backyard hens. Marek’s is the one vaccine that you can get with day-old chicks and that makes a difference later on.

  8. Terry,
    Our girls are six weeks old and I gave them yogurt for the first time yesterday. About one third cup full for seven pullets. Read somewhere helpful in preventing yeast infections. All I need to know is do you feed your girls yogurt?

    • I also put bragg’s vinegar with the mother in their water. Do you do this? I might be reading too much. I don’t want to do anything to hurt them.

      • I wouldn’t do the dairy products until they are at point of lay, as excess calcium can harm them. You can get probiotics to go in their water (I did a post about that.) Some people swear by vinegar. I’m not in that avid camp, but it does keep the algae from blooming in the waterers in the heat of summer. Don’t overdo it. Just a splash will do.

        • Thank you for answering. I did as you said with probiotics. Just changed over to vinegar when they went into coop. You’re the reason our girls are safe and thriving. I have a friend who lost some of her chicks. She thinks due to overheating. I told her about your hencam site, but she works and probably doesn’t have time to hang out for the info. Doc’s egg window glows red at nite because of color of door and red bulb from heatlamp. Really looks pretty. Thanks again and have a good day.

  9. For anybody having chickens not eat the Oystershell, try washing it first before laying it out. I think sometimes it picks up chemicals in the processing and doesn’t taste good. Now that I wash or rinse my Oystershell out through a couple of rinses of water ( I pour that on plants that like calcium). they eat a great deal more than they did before.

  10. Great information! I have an enclosed run like yours but a bit smaller. After days of rain its jusr drying out. I am wondering after a year of having birds in the same spot do you ever refresh your soil by adding top soil or anything? I read something about this before getting chickens but now I can’t find anything. What are your thoughts. Like you I free range only when I am out there to keep an eye on them. I work from home so they get out 30-40 minutes at lunch and thn 2 hours in the evening while its light out late.

    • The run can get compacted and slick. I rake it frequently and remove the manure that I can. Once a year it gets turned over with a shovel. As needed I add coarse builders sand which improves drainage.

  11. Very interesting. My first flocks got to 3 years old, some of them. It seems we’ve had these odd eggs off and on over the years. The first time it happened years back, they weren’t eating the oyster shell, so I took the fine stuff from the oyster shells and sprinkled it on their fish they get every morning. The egg shells improved and eventually they started eating the oyster shell and I stopped the fines on fish.

    This time, this spring, we again had the problem. Used the fines on fish again. They started eating the oyster shell again, but we’re still getting the odd eggs. I suspect it came in with wild birds, as the woods are 50′ away and we are very rural. I suspect the egg drop syndrome, only because I see occasional diarrhea that has no explanation.

    But production has stayed within limits, around 70 -75% ROL, this year, even with half the flock going broody at one time or another since February. Flock is 16 birds.

    As you say, they will not be enclosed inside, and while I now only keep layers for 1.5 years, we still have the pet from the original flock. So I guess for me, the answer is to feed them the best we can, and do what we can to promote health.

    • From what I’ve read, the virus does not last long outside of the animal. If you pasture your birds, perhaps you can move everything to new ground for one season. Also, the studies show a 100% morbidity (not death, but animals that show symptoms.) Studies not done on systems like yours – not crowded, fresh air, etc. I wonder if you could tweak your system to lessen the effects even further.

  12. Off subject, why do you shut Phoebe in her hutch in the middle of the day?

  13. I’m worried about one of my hens – a Goldline. She has always been a good layer but for the past four days has laid eggs with soft or no shell. What should I do? She is ten months old.