I have a huge problem with soft shells in my laying chickens. My ducks have bulletproof, hard and thick shells. They eat the same feed, a layer pellet. Though a friend once told me she loves the thin chicken shells because they are so easy to crack, I do not love them because they are fragile and they don’t last very long in the fridge.
I find that eggs don’t really “rot” when refrigerated (unlike if you find an old one that’s been sitting out in open air, pee-ew!). But they do start to dry out. When this happens, it compromises the aesthetic quality of the egg from a cooking standpoint. The strength and integrity of the yolk and its separation from the white starts to decline. If you try to fry eggs over easy (which is our favorite way to eat them), the yolks break really easy in an aged egg. And even cracking them into a bowl for scrambling or baking, the yolk just kind of splooges out in a runny mess, and it just looks bad.
They cook up fine. And in fact, older dried out eggs make better hard boiled eggs, the peel neater. Too-fresh eggs make that miserable mess when peeling, where bits of the white leave with the shell, which is so frustrating if you’re trying to make pretty deviled eggs.
So I find that about two weeks in the fridge is the limit or my chicken eggs before they just look unsightly. We eat the older ones, and I use them in our dog food, but I only sell them when they are fresher. The duck eggs by comparison- boy, they last a long time. Even after a month in the fridge, I can see no decline in quality. I haven’t managed yet to keep any long enough to where I thought they were starting to look poorly, I’m guessing it would be three months or more.
So, what to do to fix this soft shell problem in my hens? The universal advice is to offer oyster shells free choice, which I have been doing for over a year with no improvement. I also experimented with all purpose poultry feed, and also a high protein feed meant for growing turkeys. The layer pellet feed they are on is, in theory, optimized for egg production. But my suspicion is that they eat so much “other stuff” being free ranged, that they are being pushed into some kind of dietary imbalance. (Who knew that abandoning confinement feeding practices and trying to be more natural would actually be bad for them. 
) We do have weird soils here, and they eat a lot of grass.
So here I am, contemplating mineral imbalances in my chickens just as in my sheep. I haven’t found a lot of scientific advice on this, other than that we know that the calcium : phosphorous ratio can screw up either calcium or phosphorous absorption. Ironically it sounds like they can actually get soft shell problems from eating too much calcium (thus creating a phosphorous deficiency) as well as not enough. It’s interesting, considering that for ruminants, there is a ton of advice available on mineral supplementation. But it must be that animals that eat only a single grass source are much more vulnerable to imbalances; whereas omnivore poultry have less of a problem with this, so it’s not nearly as studied.
So the next thing I’m going to try is offering them the Cattlemen’s mineral supplement. Since it’s specifically designed to compensate for weaknesses in our local soil, maybe it’ll help. I’m sure tired of eggs cracking just from the slightest jostling, or even just a chicken stepping on them in the nest box!
The Collie Farm Blog 
May 16, 2011 at 3:03 am
I’ll be watching you on this one. My 7-week old pullets are on grass now. I am using electric fence like you and they are still getting out.
May 16, 2011 at 3:21 am
Do you ever feed their shells back to them? I know some think this is unsanitary but this is what we have always done to our grass-fed chickens and their shells are very strong.
May 16, 2011 at 4:03 am
Our hens will be back on grass next week–their new chicken tractor is almost finished and then they can move out of the Winter Palace.
We have a single hen who lays “water balloons.” Always the same color, and laid in the same location, so it’s probably just the one chicken. They all eat together–I cannot fathom what this hen does differently from the others, so I will be watching your blog for results!
At least the dogs are happy when I drop “water balloon” eggs on the lawn!
May 16, 2011 at 6:14 am
Heh. The benefit of living in the desert is that my hens lay very consistent eggs – thin shells on layer mash, thick shells with supplemental oyster shell. They get table scraps too of course, but it’s not in great enough quantities to mess up the mineral ratios of the bought feed.
I’m still jealous of your green stuff!
May 16, 2011 at 7:23 am
Our hens have a large field to free range. I offer free choice oyster shell, but I’ve come to the conclusion that not all the hens eat it. When we have a real problem with weak shells I’ll mix it in with the laying pellets. All the hens have to go to that feeder, so I hope they will all take some oyster shell as well. Some hens though may be just genetically inclined to lay thinner shelled eggs. I was told by a government fellow with the poultry division, that a good egg layer can not take in enough extra calcium to replace all that she is putting out if she is laying eggs most days of the year. Which would explain why the shells get weaker as the hens get older.
I was also told to feed 18% laying pellets if the hens are on pasture. The extra protein would be to compensate for all that greenery I guess.
When the avian flu came through here a few years ago, and all our chickens were killed, we kept a lot of eggs that we were still eating three months later. They were mostly fine, other than the odd one whose white was taking on a bit of a green tinge:)
May 16, 2011 at 10:50 am
As hens get older, their eggs generally get larger. Essentially, they put the same amount of calcium into making a pullet egg that they do in a 2 year old hen egg. Younger chickens should make thicker egg shells.
There is a surprising amount of calcium in green leafy stuff that would be a chicken’s choicest forage. If your soil is highly acidic, you may have a deficiency in the forage which can be corrected with the addition of lime which would also help the chickens.
If it were me, I would buy a bulk quantity of crushed shell (in my case, I would collect and crush them) and spread it on the field. Some of the calcium will be absorbed by the plants and some will be picked up by the chickens as grit.
May 16, 2011 at 7:41 pm
Michelle,
Are you feeding grit? Is the stuff in the purple pan oyster shell? I’ve never seen it look like that. I have learned that calcium/magnesium is better absorbed when there is adequate vitamin D and also copper available. I have another idea you may want to try. Add one cup of raw apple cider vinegar per 5 gallons of water to their drinking water. This also prevents pasty butts in new chicks. According to Jarvis, this will increase the absorption of calcium and facilitates the body putting the calcium where it most needs to go. Dunno, it’s worth a try, at least in my book. =) Whenever I notice the eggshells getting thin in any of my older hens, I know it’s a sign that it’s been too long since I made any dolomite available to them. It’s always been a simple fix in my experience. I do find it interesting that the oyster shell isn’t resolving the problem for you. Will be looking forward to learning how you resolve this issue.
Doris
May 16, 2011 at 8:01 pm
We have had the same issue from time to time (seems like it’s late winter tho, not in spring when things are greening up…) Oyster shell seems to help, I often mix a little in with the feed, (I like to hope it get’s mixed in and consumed by accident). If you flock is older, perhaps it’s a sign of age?
May 17, 2011 at 3:31 am
Thanks for your comments everyone! So, answers to a few questions:
My oldest chickens are just 3 years old, and started having soft shell problems in their first year of laying. It’s definitely worsened over time, and I do have them “lay through” the winter, so time/age is a factor, but apparently not the main one, since it started early.
I have a batch of chickens from a different hatchery that I bought last August, of course their eggs are still OK since they just started laying around December. It’ll be interesting to see if there is any genetic difference there. These are RIRs, and though I don’t really keep track, my guess is they average around 250 eggs per year.
Dean: I have a few chickens that have figured out how to get out of the hotwire, but the put themselves away at night! 🙂
Julie: I haven’t fed chicken eggshells back to them, mostly because I sell the majority of our eggs so I don’t have the shells. And I’m not sure what the WSDA thinks about doing that when you sell eggs to others, though I wouldn’t be afraid of doing it if I were the only one eating the eggs and I had them available.
AareneX – I get those water balloon ones very occasionally as well. It’s interesting that you have a chicken that does them consistently, rather than just a one-off, she must have a messed-up manufacturing plant in there that just always skips the last step of laying down the outer shell!
Karen-I think I went up to made-for-turkeys 22% protein feed for a while, and I thought maybe that made a slight improvement, but not much, and it could have been me just being hopeful. Our forage tests in the 20% protein range as well, though I don’t know how much nutrition birds are able to extract from grass, as compared to ruminants. [And BTW how awful to hear you had to slaughter all your birds during the Avian Flu-I’ve heard that was a very heartbreaking time for all involved!]
The oyster shell I feed is big. I’ve read some opinions that this is good, that it sits in the crop and is slowly ground down, dispensing small amounts of calcium consistently. But sometimes I wonder if that’s true, and whether possibly dolomite or some other source may be more bio-available? I may tinker with dolomite too, but am going to start with Cattlemen’s first.
Doris, I don’t offer any purchased grit, since they have unlimited access to natural grit. The ones I’ve butchered look like there is plenty of grit in their crops, so I think they are OK there (not to mention the giant oyster shell bits probably also act as grit). The stuff in the purple bowl is the Cattlemen’s mineral supplement I just started offering to them. They were very keen on it.
Bill- our soil and forage test above average for calcium, though again I don’t know how well birds do at breaking down grass compared to ruminants, versus just filling up on it? Our soil pH is somewhat low, at 5.3, but since we have 14 acres, I haven’t yet tackled the project of widespread fertility alteration, I’m just using the stopgap of offering feed supplements instead to compensate for our various soil weirdnesses.
Doris- I have used ACV before, I offered it for a few months when I noticed several chickens had diarrhea, which did seem to clear up, but I did not notice any change in shell thickness. Vitamin D shouldn’t be an issue since they’re in daylight all day every day. But copper, yes, we are definitely deficient in our soils here, with many copper binders. The Cattlemen’s supplement has very high copper, so if that is a factor, I may see an improvement.
Phew! Good discussion!
Michelle
September 4, 2011 at 5:34 pm
Hey! Two of my silkie chickens just died 😦 and I think I found a fertile silkie egg my last hen layed. It is long and thin. Is this a silkie egg or is it something else? I have many chickens and just keep them as lawn ornaments.
September 4, 2011 at 7:13 pm
Natalie, I’m not sure, I’ve never kept a “fancy” breed, so I’m not sure how their eggs might look compared to a more utilitarian breed. But it would seem that since silkies are so very divergent from standard chickens, it may make sense if their eggs are also very different. Are you going to try to hatch it?
Michelle