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Soft
or missing egg shells (sometimes called shell-less eggs) are quite
common in older birds, especially high production hybrids / good layers,
especially as they come into or out of lay for the season. A ‘soft
shelled egg’ is one that has a membrane but no shell.
This short clip shows you the difference between a thin egg-shell and a soft egg without a shell, just the membrane:
Back
garden chicken-keepers are often concerned when they find a
soft-shelled egg so this article aims to provide information about the
causes of these strange eggs.
Some causes of soft-shelled eggs
Here
are some of the reasons chickens lay shell-less or thin shelled eggs. I
don’t think this list covers every situation but should cover the
majority of cases.
1. In good layers
Good layers are the
usual candidates for soft / shell-less eggs. For example hybrid hens
have been selectively bred to lay hundreds of eggs (it’s not uncommon
for the commercial ‘brown hens’ we see to lay 320 or more in a year) and
I believe they are just producing eggs faster than they can shell them.
The normal ‘shelling process’ usually takes around 24 hours and I have
had hens produce a perfect egg followed by a shell-less egg in less than
12 hours.
In pullets (female chickens under a year old),
sometimes an egg stays in the shell gland for too long and is often
covered in excess calcium (see
calcium coated shells),
then the egg that follows doesn’t spend long enough in the shell gland.
Again, the two eggs are laid closely together on the same day.
Having
kept hybrids alongside pure breeds for many years, I’ve seen far more
instances of shell-less eggs with the hybrids. Maybe we’ve pushed mother
nature to the limit in our quest for more eggs?
2. Hot days
Thin
egg shells or shell-less eggs can occur more frequently on hot days.
This is associated with a lower food intake and shell thickness / shell
will return to normal when the temperature drops again and your
chicken’s food intake returns to normal. There have been some mentions
of this in commercial farming where they see lower intakes of food on
hot days and lower shell quality.
3. Insufficient shell-forming material
This
is the most obvious, but I have only listed it as number 3 because most
of us these days are feeding our birds with a modern balanced feed and
our hens have some access to free range and grit. Poor shells however
can occur if hens aren’t supplied with sufficient shell forming material
(mainly calcium). Chickens get calcium from soluble grit often called
Oyster shell grit (shown right) and this should be supplied either on its own or as ‘mixed grit’ which includes flint grit for digestion too.
Another
big source of calcium in a hens diet comes from their food. If you look
at the ingredients on the back of layers pellets, you will see there is
far more calcium than other feeds such as growers pellets. Fresh greens
also provide hens with a source of calcium.
4. Old age
Some
birds can lay more soft egg shells as they age. Again, this is
particularly true of hybrid breeds that have been optimised to give as
many eggs as possible during their first year such as the
Bovan Goldline
often found on commercial farms. Once these birds reach 4 or 5 years
old, you may find they start to lay eggs with soft shells. If you are
keeping ex-batts then our section of
Rehoming Ex-Battery Hens has a number of articles, specifically for ex-battery hens and their needs.
5. Insufficient protein in the diet
Chickens
need the correct level of protein in their diet as well as minerals and
various other vitamins. Vitamin D3 (Cholecalciferol) for example is
used for the metabolism of calcium and phosphorus so that they are able
to form egg shells as well as strong bones. Vitamin D is found in Cod
Liver Oil but they shouldn’t normally need this if they are fed the
correct formulated layers feed, are free range and have sunshine on
their backs.
6. Overweight hens
Chickens that are over
weight can stop producing eggs altogether or produce lower quality eggs,
sometimes with missing shells. Take a look at the breast of your birds,
when the feathers are parted, you should see the skin is thin (almost
like tracing paper) where the breast bone protrudes forward. If there is
a thick skin, or you can’t see the breast bone clearly, the chances are
your birds are carrying too much fat.
Caution: Mixed Corn and kitchen scraps
Mixed corn or ‘scratch’ as it’s sometimes called is made up mainly of
wheat with a little cracked maize (yellow in colour). Wheat typically
contains 10% protein which isn’t a sufficient amount for a laying hen.
Maize is very fattening and hens carrying fat internally are more prone
to laying problems such as prolapse and lay more shell-less eggs.Keep corn as a treat only. A handful per day per bird is sufficient.
You can check to see that you are feeding your chickens correctly on this page:
Feeding Chickens. I only give my hens an extra handful of mixed corn on cold winter days – they can use the extra fat to keep warm.
Feeding
household / kitchen scraps is technically no longer allowed by DEFRA
but if you feed ‘allotment scraps’ (where scraps have not gone into the
house / kitchen), they can be a bit of a mixed bag of what a hen needs
in her diet. Whilst this is a way to save on feed costs, as a general
rule, scraps shouldn’t exceed 25% of a hen’s diet. Allotment scraps
should ideally be boiled and then mixed with layers mash to make a
crumbly mixture so the hen is getting a more balanced diet from the
layers feed but since you’re not allowed to even pass through the
kitchen with these scraps, it makes boiling them tricky!
The best
way to ensure a hen is getting the correct diet is to use a balanced
layers feed and then supplement this with greens and some free range for
a hen to top up with other things she needs during the peak months of
egg production.
If hens can be allowed to free range on grass or
rough ground then this is much better than any vitamin drink or
supplement. They will be able to pick up a lot of the extra grit,
vitamins and minerals they need and be a lot less prone to health
problems as well as soft-shelled eggs.
A soft, shell-less egg, laid by one of my hybrid hens.
Other reasons for soft-shelled eggs
If
the above doesn’t seem to be the cause in your case or soft-shelled
eggs are being laid regularly, then there could be a number of other
reasons:
- Inflamation of the oviduct (and there isn’t anything that can be done about this as far as I know).
- Calcium absorption problems (if the diet is correct and oyster shell grit is provided ad-lib then there is sufficient calcium available but it cannot be absorbed correctly by the hen).
- Stress.
The problem usually goes away once the cause of stress is removed. Keep
an eye out for bullying / feather picking, especially if it is
occurring around the nest boxes and you are finding the soft-shelled
eggs outside of the nest boxes. Apple Cider Vinegar is good to help hens with stress.
Soft
shelled eggs laid once in a while are nothing to worry about. Hens that
are at the start of their laying period, or have come to the end of it,
often lay a soft-shelled egg.
https://poultrykeeper.com/egg-problems/soft-thin-or-missing-egg-shells/
