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Chickens have always been popular with homesteaders, but in recent years, duck keeping is increasing vastly, with the number of ducks being kept by homesteaders is rapidly catching up with the number of chickens.
There are three main reasons ducks lay soft-shelled or rubber eggs and these are lack of calcium in their diet, lack of vitamin D in their system, or because they are young birds and their oviducts and not fully developed yet. Ducks may also lay soft-shelled eggs if they are stressed or unwell.
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What is a soft-shelled egg?
A soft-shelled egg is a duck, or chicken egg, that has been laid without the proper development of a shell. These eggs are often referred to as rubber eggs because the membrane that surrounds the egg yolk and white has a strong, rubbery consistency. It is often said that soft-shelled eggs look and feel a lot like a water balloon.
When a duck produces an egg, she starts off with a yolk, which then passes through her oviduct where the white, membrane, and shell are all added prior to the egg being laid.
When a duck lays a soft-shelled egg, something has gone wrong with her systems somewhere between where the membrane is created and the shell is added.
If you keep ducks, or chickens for long enough, you will at some point come across a duck laying soft-shelled eggs.
The video below explains how chicken eggs are created inside the mother hen, and the principle is essentially the same in ducks.
What causes a duck to lay soft-shelled eggs?
As mentioned above, the three main causes of soft-shelled eggs in ducks are lack of calcium in the ducks’ diet, lack of Vitamin D, or because the female duck is too young and her oviduct has fully developed yet.
Other causes of soft-shelled eggs in ducks include because the ducks are being stressed by something or because the female is unwell. If left unaddressed, any of these factors can eventually lead to your duck stopping laying eggs altogether.
Lack of calcium in the ducks diet
Calcium is an essential building block of eggs, as well as the ducks’ bones. A duck that lacks calcium will initially show signs of her lack of calcium by laying soft-shelled eggs, but if the problem isn’t rectified, her bones may become weak and brittle as her body draws on their calcium to put towards egg production.
If an average duck egg contains between 2g and 3g of calcium, and your duck lays 200+ eggs a year, there is a clear indication that she needs calcium in her diet if she isn’t to suffer.
The easiest way to prevent your ducks from producing soft-shelled eggs due to lack of calcium in their diet is to supplement their food with crushed oyster shells.
In my experience, if you keep ducks, or chickens for that matter, they should always have a source of crushed oyster shells. You can either mix it in with their food or just spread it around their pen for them to find when they are foraging around for food.
Crushed oyster shells are not expensive so you can be generous spreading them around. I ordered this pack from Amazon.com and it was really very cheap.
Lack of Vitamin D in a ducks diet
Just like us humans, ducks need Vitamin D in their diets to help with the formation of healthy bones, and in ducks, eggs.
Ducks produce Vitamin D inside their bodies through exposure to sunlight. During the summer, or if you live in warmer climates, this isn’t usually a problem. However, if you live somewhere like the Pacific Northwest, where there can frequently be long spells of dark or cloudy weather, the lack of exposure to the sun can lead to a lack of Vitamin D in the ducks’ bodies.
Ducks that have a lack of Vitamin D in their systems soon suffer from either weak, thin-shelled eggs or eggs that are completely shell-free. This problem is often compounded by a lack of calcium in a duck’s diet as their need for Vitamin D increases with a lack of calcium.
Fortunately, getting additional Vitamin D into a ducks system is extremely simple, you just need to add a vitamin supplement to their diet. For a long time now I have had good success with this supplement that I just order from Amazon. It is reasonably priced and lasts for quite a long time as you only have to add 1 cup to 40lbs of duck feed.
Ensuring a duck has a balanced diet in general, with access to lots of fresh greens, including grass, will also help keep their vitamin and mineral levels in balance.
Female duck is too young
Depending on the breed of duck in question, ducks usually start laying eggs anywhere from 17 weeks to 30 weeks old. This can however vary due to a number of different factors.
It is not uncommon for female ducks to start laying eggs before their oviduct is fully mature. When this happens, soft-shelled eggs are usually laid. If you are getting soft-shelled eggs from a very young duck, I wouldn’t worry about it.
If she has only been laying for a couple of weeks, just leave her be. Her system is just slightly out of sync, and it usually all catches up with itself after a week or two.
Other factors that cause ducks to lay soft-shelled eggs
Stress should never be underestimated in any animal. It can take a real toll on their bodies. If a duck is laying soft-shelled eggs, and she has access to plenty of calcium and Vitamin D, stress could be the cause.
Stress can be caused by an almost limitless number of different factors. The most likely are predators or pests being present on a regular basis. Foxes and rats are probably the most likely culprits for most homesteads, but snakes, opossums, skunks, and birds of prey may also be a problem, depending on where you live.
If you believe stress may be a factor, take a look at your ducks’ home and surrounding area and see if there is anything you could change or improve to prevent predators either accessing the pen or the ducks from seeing the predators.
Ducks are generally hardy and robust, and when given clean conditions to live in and a good quality balanced feed they rarely become unwell.
However, if a duck is laying soft-shelled eggs, it may be an early indicator she has picked up a disease or infection. Take a look at this excellent article on duck health from Cornell University.
Can you eat soft-shelled eggs?
Yes! Providing the egg membrane is still intact, and the egg is fresh, there is no reason you can eat it like any other egg.
I would recommend using a soft-shelled egg straight away, as the shell of an egg makes up a vital part of its protection, not only from being broken but also from bacteria in the air and all around us.
My final thoughts
If you keep a flock of ducks for long enough, you will at some point come across a girl who lays a soft-shelled egg or two. It isn’t usually anything to worry about, just try to figure the source of the problem and adjust your setup as necessary.
99% of the time soft-shelled eggs are due to a lack of calcium or Vitamin D, and both are easily rectified by making a simple change to your ducks’ diet.