Have you ever gone out to your coop to collect eggs and found one that was distinctly...distinct? From time to time, eggs that look or feel strange can happen. These soft shelled or misshapen eggs can have odd shapes overall or can even have strange textures or ridges. In order to diagnose the exact cause of misshapen eggs occurring in your flock, some detective work can be necessary. There are a lot of reasons why this can happen as well as contributing factors. Ruling out reasons one-by-one may be necessary, and it is wise to start with those that are most dangerous and potentially detrimental to your flock as illness could be to blame and can quickly spread.
Check your flock for signs of illness. The most common and most likely affliction is Infectious Bronchitis. This is caused by Coronavirus and inhibits the respiratory system of chickens, and ultimately can affect the reproductive and urinary systems. It is extremely contagious and spreads quickly through a flock. If your chickens do fall prey to this illness, chances are good that they will recover but their ability to lay normal eggs may never return. Other but less likely illness that could be responsible for poor quality eggs are: Bird Flu, Ochratoxicosis (caused by feed contamination and only diagnosable through feed evaluation to find the presence of toxins and mold),and Infectious Laryngotracheiti (this affliction may go dormant but is carried throughout life and affects the respiratory system and can result in the expelling of bloody mucus).
Once you have ruled out illness as a factor, it is time to consider nutrition. If your chickens are experiencing vitamin deficiencies, this can greatly impact egg quality. Vitamins D, E, and B12, in addition to minerals such as phosphorous, selenium, and calcium are responsible for correct egg formation. The absence of these will result in malformed or soft shell eggs. To solve this problem, supplement your chickens\' diet with items such as ground eggshells, and take away any treats that could be leeching calcium away from your chickens. Keep in mind that vitamins gained from sunlight exposure are also beneficial remedying this problem.
If your chickens are not ill and are being fed properly, it is time to consider the environment. This can be a tricky problem to solve because toxins (such as mold spores) exist in nature that are not always visible to the naked eye. To start, rule out parasites, be it internal or external, by regular deworming (Piprazine, Levamisole, Fenbendazole and Hygromycin have been used successfully but minimal research has been done regarding their overall safety) and providing access to a dust bath. Minimize the stress of your chickens\' environment, such as insulating coops or putting up barriers to mute road noise or other disturbances. Also keep in mind the effects of heat and humidity-high heat can result in poor egg quality as can high or low (in other words, not \'just right\') levels of humidity.
The general consensus is that soft shelled or misshapen eggs are safe to eat (again, not backed up by research, just word of mouth) but they do not keep for very long due to their flawed shells. The egg contained inside can also vary in quality, being of less than stellar appearance and quality much like the egg that contained it, so consume at your own risk and definitely do not sell these. If you have looked into all the reasons above regarding egg malformation and cannot fix the problem, consult an avian vet for further instructions and diagnosis. While it is usually fairly uncomplicated to diagnose a problem, new problems are cropping up as old ones change and mutate, so it is better to be safe than sorry and get the opinion of a qualified vet in those situations.