reading time: 7 Session minutes
Have you ever wondered why you get bumps or changes in the color of your eggshell? Learn how eggs develop, and troubleshoot abnormal egg problems with the chicken owner and starter Elizabeth Diane Mac.
By Elizabeth Diane Mack For owners of small poultry flocks, eggshell deformities can be a little scary. Inner shell development occurs in less than 24 hours, and during this time, even minor disturbances can affect the quality and appearance of the finished eggshell. If you understand what the irregularities indicate, you can decide if you see temporary luck, or if you need to treat your bird for nutritional or health issues.
Egg development 101
Although the eggs develop quickly (over a period of 25 to 26 hours), the process is quite complex. Young life (female chickens) begin with two ovaries. As the billet grows into laying hens, the right ovary does not develop, while the left ovary is fully functional. Empty chicks are born with tens of thousands of eggs (yolks). Only a small portion of these eggs will develop into eggs, and no new eggs will develop as they mature, so chicks are born with as many eggs as they can lay.
The hen’s reproductive system has two main parts – the ovary and the oviduct. As the fungus matures, the yolk slowly develops, receiving nutrients from connected blood vessels. When the yolk of an immature egg grows to about the size of a quarter, the yolk is released from the ovary. During this stage, process hiccups may occur, resulting in a harmless spot of blood on the yolk. If a hen shoots two yolks, you will have a double-yolked egg.
The yolk then enters the oviduct, where eggshell production begins on the two-foot indoor assembly line. The yolk released is first captured by the funnel, or funnel, where the yolk enters the oviduct and remains for about 15 minutes. The yolk then moves to the magnum, and remains there for about 3 hours. The burgeoning egg then obtains its egg white protein, or albumin, by spinning through the magnum as the albumen strands are wrapped around the yolk. These “kalaza” threads center the yolk in the finished egg.
During the next stage of the process, the inner and outer shell membranes are added to the developing egg in the isthmus. The yolk remains in the isthmus for 75 minutes before traveling to the final station in egg production, the shell gland, or the uterus. Most of the egg collection time (20 hours or more) is spent in the shell gland. Calcium carbonate is converted from chicken bones to provide about 47 percent of the shell, while feed nutrients provide the rest. This is why it is so important to add oyster shells or other sources of calcium to your chicken’s diet. When the outer shell hardens, dye is also added before the egg travels into the vagina. A “plum,” or thin layer of skin, is added, and the muscles of the vagina flip the egg to get it out the big end first.
Eggshell irregularities
During this process, events can occur that result in irregular shells: anything from pimple-like bumps and wrinkles to a shellless egg. Irregularities can occur naturally, but they can also indicate that your chickens have health problems.
If you notice irregularities in the eggshell constantly, you should consult a poultry veterinarian. According to Dr. Jackie Jacob, University of Kentucky Poultry Extension Assistant, eggshell deformities can be the result of many things, including disease. “It could be something mild, like infectious bronchitis, or something serious, like Newcastle disease.”
But, says Jacob, before you consult a vet, look at nutrition first. “Many people feed a forage diluted with scratch grain or cracked corn, and a nutritional deficiency occurs. The shellless or poorly shelled hulls could be a calcium, phosphorus, magnesium, or vitamin D deficiency, or even a protein deficiency.” Jacob adds that heat stress and even harsh handling can cause dandruff problems, too.
Breeders of chickens in a small flock must note specific deformities in the shell to distinguish between simple aesthetic anomalies and signs of serious health problems.
Eggs without shell
Young hens entering laying for the first time may lay one or two eggs without the shell. In mature chickens, it is also not uncommon to find an egg without a shell under the roost. While finding this type of water balloon out of the egg can be alarming, it doesn’t necessarily indicate any major health problems.
A shellless egg is exactly what it looks like. While a membrane forms around the yolk and egg white, the shell does not. A shellless egg can be a sign of a nutritional deficiency, such as a loss of calcium, phosphorus, or vitamin E or D. If the added nutrients fail to solve the problem, shellless eggs may indicate infectious bronchitis or egg drop syndrome. (EDS). IB is a highly contagious viral disease, so the entire flock will have symptoms, not just one bird. EDS is also a viral infection that usually affects more than one bird.
Shellless eggs can also appear at the end of winter or the end of oviposition as the egg-laying “factory” returns to speed. Sometimes a shellless egg can occur if there is a disturbance in the night, such as a predator sniffing around the coop.
Hard or rubbery eggs
Similar to shellless eggs, soft shell eggs appear when the shell has not fully formed around the yolk and membrane. The membrane is thick enough to contain liquid, but lacks the calcium found in the hard shell. You can catch a soft-shelled egg by squeezing the outer membrane between two fingers, like a deflated water balloon. If shelled eggs appear in the summer heat, heat stress may be the cause. Many breeds of chicken, such as the heavier Orpingtons and Wyandottes, do not tolerate excess heat well. Fresh water in the summer months is essential to avoid shell deformities and other health problems, but make sure it’s water that isn’t soaked. While sometimes inadequate nutrition is to blame, more often this offense is caused by excessive consumption of phosphorus.
corrugated shells
This rough, irregularly ribbed appearance can be caused by a variety of external factors. Heat stress, salty or water softener, poor diet, or a vitamin D deficiency can all cause these weird, undulating bumps. While older laying hens are more likely to produce corrugated shells, mycotoxins, which are by-products of toxic organisms sometimes found in poultry feed, can also be responsible. If you have recently changed your food or your feed is stale or moldy, try treating that first. Make sure the water you use has not been “softened” or treated with lime, resins, salts, or chelating agents.
Wrinkled or wavy shells
If the egg white is underdeveloped and watery, it is difficult for the shell to develop normally, which may result in what appears to be wrinkled shells. As a hen ages, it is normal for the egg to become thinner, which can lead to a rippled outer shell.
However, when younger hens lay persistently wrinkled eggs, it may be a sign of infectious bronchitis, as IB prevents the hen from producing thick albumen. If the hen is on a good diet with plenty of nutrients, isn’t crowded or stressed, and otherwise seems healthy, you don’t have to worry about shell wrinkles.
Calcium deposits or blisters
Calcium deposits can take the form of hard clumps or fine sand-like particles that can be easily removed. Calcium deposits are often attributed to a disturbance during calcification of the shell while in the oviduct. Common disturbances include a predator, noisy thunderstorms, or a bullying chicken. While it is possible for excess calcium in the diet to be a factor, it is not common. As with many other cortical abnormalities, the cortical gland (uterus) can also be the cause.
pale shells
Different chicken breeds lay eggs in every color of the rainbow, from the pure white Leghorn, to the dark brown Welsummer and Maran. But what about the layer that produces eggs that are naturally brown and look pale? The pigment of the eggshell is deposited in the sac of the shell gland. If the cortex gland is defective in any way, the quality of the pigment suffers. Although it is not uncommon for older hens to lay pale eggs, younger layers whose eggshells are abnormally pale may suffer from infectious bronchitis.
misshapen eggs
Round shells, oblong shells, football shells, or any shape other than the oval base are all considered deformed. Irregular shapes are a greater concern in large egg production, as consumers expect their eggs to be uniform and perfect. Overcrowding and stress can cause abnormal shapes, as can many diseases. If you notice deformed eggs regularly, have your vet tested for diseases such as avian influenza, infectious bronchitis, and Newcastle disease.
Examined egg from the body
A shell with a pronounced “belt”, or extra shell layer around the middle, occurs when a cracked shell in the oviduct forms a layer of calcium carbonate, which results in a noticeable raised bump around the center of the shell. While older hens have a higher percentage of body-checked eggs, this abnormality can also be caused by stress or overcrowding in the coop.
When to seek treatment
In a small backyard flock with a good diet and adequate clean water, the most common causes of rutting irregularities are overcrowding and stress. If a laying hen is frightened by a predator, passage through the oviduct can be temporarily stopped. This delay can cause additional calcium carbonate to be deposited on the shell, causing elongated waists, thin scales, or other irregularities. Sometimes, there is no apparent reason for a single egg to become deformed.
Irregular shells are a bigger problem for large-scale production, as an abnormally shaped egg will not fit easily into an egg carton and may be more likely to break during transportation. If you are hoping to hatch chicks, you should avoid using abnormally shaped eggs, as shell problems are sometimes hereditary.
If you notice consistent egg abnormalities over several days or weeks, you should check with your vet about possible disease in your flock, especially if more than one chicken appears to be affected.
A hen who receives a healthy diet of good quality layer feed and oyster shells, who does not show symptoms of respiratory disease, and who has plenty of safe space to roam may still occasionally lay individual eggs. These problems are temporary, and the eggs are safe to use. So enjoy your eggs.
Freelance writer Elizabeth Diane Mac He keeps a small flock of chickens on a 2-acre hobby farm outside of Omaha, Nebraska. Her work has appeared in Capper’s Farmer, Out Here, First for Women, Nebraskaland, and many other print and online publications. her first book, Healing Springs and Other Stories, includes her introduction—and subsequent love affair—with raising chickens. Visit her website at BigMackWriting.com.