Storey's Guide to Raising Chickens (58 page)

YOLK COLOR ORIGINS

Occasionally, you may find an egg, or a cache of eggs, and not know how long ago they were laid. Several different methods allow you to estimate an egg’s age.

You can examine the interior of an egg using a small, bright flashlight.

Candling
is the process by which an egg’s contents are viewed in front of a light, even though no one actually uses a candle anymore. Poultry-supply outlets offer a handheld light designed specifically for the purpose, but a small, bright flashlight works just as well.

If you have never candled an egg, practice with white-shell eggs before you tackle colored ones, which are more difficult to see through. In a darkened room grasp an egg at the bottom between your thumb and first two fingers. With the egg at a slant, hold the large end to the light. Turn your wrist to give the egg a quick twist, sending the contents spinning.

The albumen of a fresh egg is fairly dense. If the yolk looks vague and fuzzy, the thick white albumen surrounding it is holding it properly centered within the shell. As the egg ages and the white grows thinner, the yolk moves more freely. When you twirl the egg, the deteriorating albumen lets the yolk move closer to the shell. A yolk that’s clearly visible indicates albumen that has thinned.

Air-cell
size increases as an egg ages. Unlike a slightly older egg, a freshly laid egg has no air cell under the shell at the large, round end. As the egg cools and its contents shrink, an air space develops. The inner shell membrane pulls away from the outer shell membrane, forming a cell, or pocket. As time goes by moisture evaporates from the egg, its contents continue to shrink, and the air cell grows.

Candling to measure the air cell will give you an idea of the egg’s age. The cell of a freshly laid cool egg is no more than J-inch (3 mm) deep. From then on, the larger the cell, the older the egg. Just how fast the air space grows depends on the porosity of the shell and on the egg’s storage temperature and humidity.

Floating
an egg in plain water lets you gauge its air-cell size without candling. A fresh egg will settle to the bottom of the container and rest horizontally. The larger air cell of a 1-week-old egg will cause the big end of the egg to rise up slightly from the container bottom. An egg that’s 2 to 3 weeks old will stand vertically at the bottom of the container, big end upward. When the air cell grows
large enough to make the egg buoyant, the egg will float. Although a floating egg is quite old, it’s not necessarily unsafe to eat.

Smell
is the quickest way to detect the age of an egg that’s too old to eat. A rotting egg emits foul-smelling hydrogen sulfide, otherwise known as rotten-egg gas. Any egg with an off-odor, whether raw or cooked, should be discarded.

Breaking an egg
and examining its contents is another way to estimate the egg’s age. The albumen of a fresh egg contains carbon dioxide that makes the white look cloudy. As an egg ages, the gas escapes and the albumen looks clear or transparent.

A fresh egg’s albumen is also firm and holds the yolk up high. A stale egg has watery albumen that spreads out thinly around the yolk.

Photocopy gauge, paste over cardboard and cut out. To measure an air cell, place gauge over the large end of an egg held in front of a light.

FLOAT TEST

An easy way to determine an egg’s age is by placing it in water. Older eggs have larger air cells and will therefore float.

As an egg ages, water migrates from the albumen to the yolk, stretching and weakening the yolk membrane. The older the egg, the greater the likelihood that its yolk will break.

Even the freshest egg occasionally has a watery white or an easily broken yolk. But if an egg has a mottled yolk or otherwise doesn’t look right to you, discard it.

You may occasionally find an egg that is abnormal due to an accidental occurrence, a hen’s hereditary tendencies, or environmental or management factors. Some egg abnormalities are little more than nonrecurring curiosities, and others may require corrective action on your part. You can detect these abnormalities by candling and by inspecting broken-out eggs. Trapnesting (as described in
chapter 9
) lets you identify hens that habitually lay problem eggs.

No-yolkers
are called
dwarf eggs
or
wind eggs
. They most often occur as a pullet’s first effort, produced before her laying mechanism is fully geared up.

In a mature hen, a wind egg is unlikely but can occur if a bit of reproductive tissue breaks away, stimulating the egg-producing glands to treat it like a yolk and wrap it in albumen, membranes, and a shell as it travels through the oviduct. In place of a yolk, this egg will contain a small particle of grayish tissue.

In the old days no-yolkers were called cock eggs. Since they contain no yolk and therefore can’t hatch, people believed they were laid by roosters.

Double yolkers
appear when ovulation occurs too rapidly or when one yolk for some reason moves too slowly and is joined by the next yolk. Double yolkers may be laid by a pullet whose production cycle is not yet well synchronized. They’re occasionally laid by heavy-breed hens, often as an inherited trait.

Sometimes an egg contains more than two yolks. One time I found an egg with three. The greatest number of yolks ever found in one egg is nine. Record-breaking eggs are likely to be multiple yolkers: the
Guinness Book of Records
lists the world’s largest chicken egg (with a diameter of 9 inches [23 cm]) as having an amazing total of five yolks and the heaviest egg (1 pound/0.5 kg) as having a double yolk and a double shell.

An egg within an egg,
or a
double-shell egg
, appears when an egg that is nearly ready to be laid reverses direction and gets a new layer of albumen covered by a second shell. Sometimes the reversed egg joins up with the next egg, and the two are encased together within a new shell. Double-shell eggs are so rare no one knows exactly why or how they happen.

Blood spots
occur when a small blood vessel ruptures and a bit of blood is released along with a yolk. They appear in less than one percent of all eggs laid and do not mean the eggs are unsafe to eat.

Each developing yolk in a hen’s ovary is enclosed inside a sac containing blood vessels that supply yolk-building substances. A mature yolk is normally released from the only area of the yolk sac free of blood vessels, called the
stigma
or
suture line
. Occasionally a yolk sac ruptures at some other point, causing vessels to break and blood to appear on the yolk or in the white. As an egg ages, the blood spot becomes paler, so a bright blood spot is a sign the egg is fresh.

Spots may appear in a pullet’s first few eggs but are more likely to occur as hens get older. They may be triggered by too little vitamin A in the diet or may be hereditary — if you hatch replacement pullets from a hen that typically lays spotty eggs, your new layers will likely do the same.

Meat spots
are even less common than blood spots, but like blood spots, they may be hereditary. They appear as brown, reddish brown, tan, gray, or white spots in an egg, usually on or near the yolk. Such a spot may have started out as a blood spot that changed color due to a chemical reaction or may be a bit of reproductive tissue. Meat spots look unappetizing but do not make the egg unsafe to eat.

Wormy eggs
are extremely rare, occurring only in hens with a high parasite load. Finding a worm in an egg is not only unappetizing but is a clear indication that you are not doing a good job of keeping your hens healthy and parasite free.

Off-flavor eggs
may result from something a hen ate or from environmental odors. Hens that eat onions, garlic, fruit peelings, fish meal, fish oil, or excessive amounts of flax seed will lay eggs with an undesirable flavor. Eggs can also absorb odors that translate into unpleasant flavors if they’re stored near kerosene, carbolic acid, mold, must, fruits, and vegetables.

Developing embryos
are a sign that eggs have been partially incubated, which occurs when hens hide their nests and the eggs accumulate. In laying
subsequent eggs, the hen may warm the earlier eggs enough for them to start developing. Or a hen may have started setting and later gave up.

If you find a bunch of eggs and you can’t be sure how long they’ve been there, inspect them either by candling or by breaking them into a separate dish before using them. You will not get developing embryos if you have no rooster to fertilize eggs or your housing is set up so the hens can’t readily hide their eggs.

A freshly laid egg is warm and moist and therefore attractive to a variety of bacteria and molds in the environment. As an egg cools and its contents shrink, these microbes may be drawn through the shell’s six thousand–plus pores. Your first line of defense in keeping eggs safe to eat is to keep nests clean and lined with fresh litter. Eggs produced in a clean environment, collected often, and promptly refrigerated contain too few microbes to cause human illness.

An egg that’s cracked — called a
check egg
— is safe to eat, provided the membrane is intact, the egg is refrigerated promptly, and it’s used right away. If a cracked egg leaks, indicating the membrane has also been broken, discard it.

Discard any eggs that are seriously soiled. Although moderately soiled eggs may be washed, in doing so you’ll rinse away the bloom that seals the pores and keeps out bacteria. If you do wash an egg, sanitize the cleaned shell by dipping the egg for 30 seconds in a solution made up of 1 teaspoon of chlorine bleach and 1 quart of water warmed to 101°F. Wipe the egg dry with a clean paper towel or soft cloth before placing it in a storage carton. Rubbing the shell with clean vegetable oil before refrigerating the egg will prolong its shelf life.

Clean eggs stored at 45°F (7°C) and 70 percent humidity will keep well for at least 3 months. In a standard household refrigerator, where foods tend to dry out thanks to the refrigerator’s defrosting mechanism, eggs will remain edible for up to 5 weeks.