Eggs
NOT AS SIMPLE AS WE THOUGHT
EVERY DAY IS EASTER IN THE HENHOUSE,
but even the Easter Bunny would do a double take at some of the funky finds from our feathered friends. The egg-making process is so complicated, it’s miraculous that most are perfect!
All in one basket.
What to Expect When You’re Eggspecting
Most pullets lay their first eggs between 5 and 6 months old, but there is a wide range of “normal” that extends from 18 weeks to 12 months old. My Silkie, Freida, didn’t lay her first egg until 14 months of age!
The “point of lay” is influenced by many factors: breed, hormones, diet, health, lighting conditions, temperatures, and stress. Pullets offer a few physical clues as they approach the point of lay: their combs and wattles begin to darken and they may begin exploring nest boxes, rearranging nesting material and sitting in them. But the best clue that a pullet is about to lay is what I call “the submissive squat,” a deferential posture a sexually mature pullet or hen typically assumes when approached by a rooster. She crouches, spreads her wings to the side for balance, and lowers her tail.
Eggs from backyard chickens should be fresher, more nutritious, and safer to eat than commercially produced eggs. But that will not be the case if eggs are contaminated before they ever reach the kitchen.
There are a few things you can do to prepare for your flock’s first eggs. As always, clean water and a complete feed are paramount. Begin feeding layer ration when the first pullet lays an egg or by 18 weeks of age, whichever comes first. Because layer feed contains a quick-release form of calcium, slow-release calcium in the form of oyster shells should be made available in a separate container near the feed. Each hen has unique requirements and will consume as much calcium as she needs, so don’t worry if the oyster shells don’t seem to be disappearing. Resist offering pullets layer ration prematurely, though, as the calcium content can cause kidney damage and gout in immature birds. And don’t underestimate the importance of clean drinking water; an egg consists of approximately 75 percent water and hens are unable to produce eggs without it.
Make nest boxes welcoming, one for every four layers. I believe this communal nesting preference is an evolutionary instinct—a shared nest is easier to protect than individual nests scattered hither and yon. Consider nest box curtains to satisfy the hens’ desire for concealment, particularly if the nest box area is brightly lit. Place a dummy egg or a golf ball in each nest box to tap the power of suggestion.
Because hens squat when laying, nest box bottoms should be cushioned to prevent shell breakage. Nesting material can range from pine shavings to plastic pads and chopped hay/straw/zeolite litter blends. Hens do seem to enjoy rearranging nesting material, but its more important function is protecting eggs, not amusing the hens. I don’t recommend regular straw due to its propensity to harbor mites and mold and cause crop impaction. Nesting material should be easy to remove because eggs do break occasionally. I enjoy the scent of dried herbs and flowers in my nest boxes, but the aromatherapy benefits are mostly for me, as chickens have a relatively poor sense of smell.
Finally, do not disturb! Limit activity in and around the coop in the morning for a stress-free environment. Don’t check on them every 10 minutes, trying to catch an Instagram-worthy action shot of an egg shooting from her hindquarters. Egg laying is a solitary endeavor deserving tranquility. Reserve coop chores until later in the day, keep small children from engaging the hens, and let them put the finishing touches on their masterpieces undisturbed.
The best clue that a pullet is about to lay is what I call “the submissive squat,” a deferential posture a sexually mature pullet or hen typically assumes when approached by a rooster. She crouches, spreads her wings to the side for balance, and lowers her tail. White Crested Black Polish hen, Doc Brown.
Tips for Clean Eggs
Eggs from chickens that forage in a backyard should be fresher and more nutritious than commercially produced eggs, but that will not be the case if eggs are contaminated before they ever reach the kitchen. Accidents happen and occasionally an egg becomes soiled with droppings or dirt tracked into the nest by a wet hen, but most eggs from backyard chickens should be clean when collected. In addition to providing one nest box for every four hens (hens unable to find nest box space may lay their eggs elsewhere), there are other simple steps you can take to maximize egg cleanliness.
HEN ANATOMY
Prevent birds from sleeping in nest boxes. Train chicks to roost and retrain if necessary. Position roosts higher than nest boxes to meet chickens’ instincts to sleep high off the ground. If roosts are lower than nest boxes, they’ll sleep and poop in the boxes.
Remove broody hens to dedicated maternity wards. Chicks raised in nest boxes will be trained to sleep in them, leaving behind dirty nests.
Collect eggs frequently. The less time eggs spend in the nest boxes, the less likely they are to be broken, eaten, or soiled. Rollout nests are a good option.
Cushion nest boxes. Eggs won’t break if they have a soft landing. I use plastic nest box pads and bottoms that are easily washed and sanitized. Avoid using materials chickens will scratch out, leaving eggs unprotected.
Ensure clean feet. Dirty, wet feet can be dried and cleaned en route to nest boxes with dry litter such as sand and pine shavings.
Aim for clean vents. Dirty vent feathers put eggs at risk for contamination. Hens with loose droppings or chronically dirty vents should have butt baths as often as necessary until the cause can be determined and rectified (see chapter 8).
Occasionally, birds will soil the nest despite your best efforts. Check nest box cleanliness each morning before eggs are laid and whenever possible during the day.
How a Hen Makes Eggs
When a hen is sexually mature, lighting conditions stimulate hormones that cause her ovary to release a yolk into the oviduct, where it acquires the albumen (whites), membranes, and shell (including shell color). The process takes 23 to 25 hours. Within about 30 minutes of an egg being laid, the process starts again.
A fertilized egg contains everything necessary to produce a chicken in just 21 days. When raising hens for eggs, it is easy to forget that the purpose of an egg is to make another chicken. However, hens in flocks without roosters are only able to contribute to the breakfast menu because an egg must be fertilized by a rooster to develop into a chick. Let’s take a look at the complex and fascinating process of egg formation.
THE OVARY AND YOLKS
A hen’s reproductive tract consists of a left ovary and oviduct set; although female chicks hatch with a right and a left set, the right side doesn’t develop, while the left grows like gangbusters beginning at 16 weeks. A female chick hatches with nearly a half million ova, which is far more than she could ever turn into eggs.
As she matures, yolks begin to develop progressively, each awaiting its turn to ripen and be released into the funnel-shaped top portion of the oviduct known as the infundibulum.
INFUNDIBULUM
The infundibulum is to the ova what a catcher is to a baseball. When the ova is released from the ovary, the catcher is waiting behind home plate to receive the pitch. In the case of a wild pitch, the ova is ordinarily absorbed by the hen’s body, but sometimes injury or disease in the oviduct causes yolks to land in the abdominal cavity and even become infected, conditions known as internal laying and egg yolk peritonitis, respectively.
Also waiting for the yolk in the infundibulum are any sperm contributed by a rooster during mating. If fertilization is to occur, it happens here. This flurry of activity occurs in a mere 15- to 30-minute window.
Finally, the chalazae are added, which are little ropelike tethers attached to opposite sides of the yolk to center it inside the shell. The chalazae are considered the first albumen layer. True story.
HEN’S REPRODUCTIVE TRACT
When a hen is sexually mature, lighting conditions stimulate hormones that cause her ovary to release a yolk into the oviduct where it acquires the albumen (whites), membranes, and shell (including shell color). The process takes approximately 23 to 25 hours. Within about 30 minutes of an egg being laid, the process starts again.
A female chick hatches with nearly a half million ova, which is far more than she could ever turn into eggs. As she matures, yolks begin to develop progressively, each awaiting their turn to ripen and be released into the funnel-shaped, top portion of the oviduct known as the infundibulum.
MAGNUM
The yolk next enters the magnum portion of the oviduct where it gets a special wrapper known as the vitelline membrane and spends approximately 3 hours collecting albumen, more commonly known as the egg white. Albumen’s job is to protect the yolk and/or embryo from contamination and to nourish a developing embryo. The vitelline membrane weakens over time, which is why yolks from old eggs break easily.
While we typically think of albumen or egg whites as a single layer of liquid inside the egg, there are actually four distinct albumen layers surrounding the yolk in the following order: the chalaziferous layer, a thin inner layer, a thick layer, and a thin outer layer, each added at different locations in the oviduct. Albumen thins as eggs and hens age, and can become watery due to a respiratory infection.
In the magnum portion of the oviduct, the yolk gets a special wrapper known as the vitelline membrane.
ISTHMUS
The next 75 to 90 minutes are spent in the isthmus, where a little more albumen is generated along with two shell membranes and the shell’s base layer of calcium crystals.
UTERUS/SHELL GLAND
The next 18 to 20 hours of egg development occur in a muscular portion of the oviduct known as the uterus. Water and mineral salts are added to the albumen in a process known as “plumping” and the eggshell is meticulously constructed. The shell contains 7,000 to 8,000 pores that allow a developing embryo to exchange oxygen and carbon dioxide with the outside environment during incubation and embryonic development.
VAGINA
The hen’s vagina stores sperm before it travels up to the infundibulum to fertilize the yolk. Shell color is sometimes added here in the final hour or so of egg making. Finally, a thin, liquid coating called the bloom or cuticle is added to the eggshell surface. The cuticle is composed of organic material and water and seals the pores. During laying, the cuticle acts as a lubricant, but the surface dries and the residue, which is mainly protein, closes off most of the pores as a barrier to the invasion of bacteria and fungi. If you happen to witness a hen laying an egg, you’ll see and can feel the bloom and watch it dry within seconds after being laid. As the egg ages, more and more pores open.
CLOACA
With the bloom in place, the egg enters the cloaca narrow end first and rotates 180 degrees just prior to being laid, wide end first.
Egg Oddities
Rookie pullets need a week or two to warm up their reproductive tracts and perfect the egg-making process. Expect first eggs to be smallish and possibly wonky-looking, but don’t worry much about the occasional funky egg from a hen of any age.
Many odd eggs can be explained by the hen’s diet, environment, or health. The following general guidelines will help you understand some of the more common egg irregularities and interesting egg factoids, but are not intended as an exhaustive review. If your hen consistently produces irregular eggs, consult a veterinarian or extension service specialist. Finally, all of these weird eggs are perfectly fine to eat.
Double yolks. These commonly occur in new layers when yolk release is mistimed and two yolks travel down the oviduct together. Some hens are genetically predisposed to laying double-yolk eggs. A double-yolk egg can hatch, but it’s rare.
No yolk. Tiny eggs containing no yolk are referred to as fairy eggs (Fig. 1), wind eggs, dwarf eggs, and fart eggs (I don’t make this stuff up). These are also common in new layers when the reproductive system is not yet synchronized, but can also occur in older hens when a piece of tissue from the oviduct breaks free, tricking the hen’s reproductive system into treating the tissue like a yolk and creating an egg.
No shell (rubber eggs). Eggs without shells (Fig. 5) feel rubbery because the membranes are on the outside. They’re commonly produced by new layers, but can result at any time from stress or often from calcium, phosphorous, or vitamin D deficiency.
Thin shells. High environmental temperatures are the most common cause of thin-shelled eggs. The hen’s increased rate of respiration interferes with calcium carbonate production and shell formation (see chapter 9). Older hens generally produce thinner shells as their oviduct wears out.
Odd shell shape or texture. I affectionately refer to these as “mutant eggs” (Fig. 2). In new layers, an immature shell gland can cause odd shell shape and is most often of no concern. In senior layers, oddly shaped eggs can result from stress or, if they are a regular occurrence, a defective shell gland often caused by infectious bronchitis.
Shells with wrinkles or “checks” are known as “body check” eggs and have been damaged while in the shell gland from stress or pressure put upon them. The cracks are repaired in the shell gland, resulting in checks or wrinkles.
Pimpled or sandpaper shells. (Fig. 3) Eggshells can have different textures caused by a number of factors, from excess calcium or vitamin D intake (pimples that can be scraped off) to double-ovulation, disease, a defective shell gland, or rapid changes in lighting (sandpaper shells).
Flat- or slab-sided eggs. When an egg is delayed in the shell gland, a second egg coming down the oviduct will bonk into it and rest alongside the first egg, causing a flat, wrinkled side (Fig. 4). This can be caused by stress or disease.
Large eggs. Eggs of unusually large size ordinarily contain double yolks, causing the hen’s reproductive system to work overtime to generate these monstrosities. Older hens tend to lay larger eggs because the oviduct loses elasticity over time.
Egg within an egg. This anomaly occurs when an egg almost ready to be laid reverses engines and backs up into the reproductive tract, where it meets the next egg in progress. The first egg receives more albumen, membranes, and shell before being laid. The cause is not known. Although the literature characterizes this phenomenon as rare (I have never gotten one from my hens), photos shared with me by other backyard chicken keepers leads me to conclude that these oddities are significantly more common than previously believed.
Blood spots. These can appear as small red dots on the surface of the yolk or as big, nasty clots that tinge the entire albumen (Fig. 6). Most are no big deal. Yolks develop inside the hen and are attached to her ovary by a follicle that’s like a balloon wrapped around a yolk. All but the neck of the balloon has a rich blood supply. The follicle is supposed to open at the neck and set the mature yolk free, but if the follicle opens at any other point, a speck of blood can attach to the yolk. No biggie. Blood spots can also occur due to vitamin deficiencies, age, or heredity.
Rookie pullets need a week or two to warm up their reproductive tracts and perfect the egg-making process. Expect first eggs to be smallish and possibly wonky-looking, like this shell-free egg (Fig. 5).
Meat spot. While blood spots occur on the surface of an egg yolk, meat spots (Fig. 7) are found in the albumen and result from a small piece of the oviduct sloughing off as albumen is being added in the egg-making process. Although visually unappealing, meat spots are safe to eat.
Unusually colored yolks or albumen. Although we expect to see yellow yolks and translucent albumen, colors are influenced by a hen’s diet. Cottonseed meal and excessive acorns, for example, can cause green egg yolks and/or pink whites. Green egg whites can be caused by too much riboflavin. These eggs are perfectly edible, although visually off-putting.
Fertilized vs. Unfertilized
The idea that an egg from a backyard chicken may be fertilized freaks out a lot of people, but there’s really no need for apprehension about what may be inside the egg if you understand the differences between a fertilized and unfertilized egg and an incubated and unincubated egg.
In order for an egg to contain both the male and the female genetic material necessary to create an embryo with the potential to develop into a chick, a hen must mate with a rooster. An unfertilized egg contains only the hen’s genetic material, which means a chick can never hatch from that egg. The hen’s genetic material, called the blastodisc, is a light-colored spot with irregular borders sitting on the surface of every yolk.
When an egg is fertilized by a rooster’s sperm, the blastodisc becomes known as the blastoderm, which appears as a bull’s-eye shape on the surface of the yolk. However, the blastoderm will remain in a state of suspended animation forever unless warmed to at least 85°F (85°C) (incubated) for several days before any change becomes noticeable to the untrained eye. If incubated under consistent temperatures and humidity levels for 21 days, the blastoderm may develop into an embryo and hatch into a chick. Fertilized eggs do not taste different from, and are no more nutritious than, unfertilized eggs. A fertilized egg that is never incubated will never contain an embryo and will never look like anything other than common breakfast food. Therefore, you can have a rooster and eat your eggs too!
Unfertilized egg (left) vs. fertilized egg (right).
Fertilized unincubated egg with blood spot (left) vs. fertilized egg with developing embryo at 4 days of incubation (right).
Candling, shining a light through an eggshell to see what’s inside, will not reveal whether the egg was fertilized. Only eggs that are incubated and begin developing into an embryo can be identified as fertilized, and then only after a minimum of 3 days by candling. It is possible for a fertilized and incubated egg to fail to develop during incubation, in which case under candling it will appear not to have been fertilized. The only way to determine whether an unincubated egg was fertilized is to crack it open and identify a blastoderm.
A blood spot in an egg does not mean the egg is fertilized or that an embryo has begun to develop. This old wives’ tale may have come about because after 3 or 4 days of incubation, a tiny vein network surrounds the embryo of a fertilized egg. Veining looks nothing like a blood spot, however.
Egg Handling
I’m often asked my opinion about egg washing and how long fresh eggs will remain “good.” I could present you with the history of egg sanitation practices in the United States and Europe. I could detail the many conflicting opinions among poultry professionals about how or whether eggs should be washed. I could even break down the advantages and disadvantages of each position for you in a happy little chart, but I’m not going to and I’ll tell you why. Salmonella from eggs is transmitted to people primarily as the result of an egg yolk that was infected with Salmonella enteritidis inside the hen’s ovary, not on the eggshell. Regardless of egg handling or freshness, there is always a risk of Salmonella contaminating chicken eggs, and the only way to avoid food poisoning is to cook eggs thoroughly (to 160°F or 71°C). Beyond that, the issue becomes how much risk you’re willing to take with your health.
As for egg handling, here are my two cents.
• Maintain nest box sanitation rather than allow eggs to be laid in filthy nests.
• Store clean eggs in the refrigerator rather than on the counter where they will degrade an estimated seven times faster (in safety and quality).
• Use fresh eggs, promptly rather than let them get old and degrade in quality and safety.
• Do not wash clean eggs because the protective bloom the hen courteously applied to them will protect them from external contamination.
• Do not consume eggs that have been soiled with poop (rather than risk cleaning them in a way that may drive bacteria through the shell’s 7,000 to 8,000 pores).
• That’s my story, and I’m sticking to it.
The Float Test
Backyard chicken keepers take great pride in their hens’ eggs, and for good reason—they taste better, perform better in baking, and are more nutritious than commercial eggs. There are times, however, when the freshness of an egg from home-raised hens may be in question, such as when eggs are found outside the coop. One method used to gauge an egg’s approximate age is the float test, whereby the egg is placed in a glass of water and its position observed. The essence of the float test is that newly laid eggs will lie flat on the bottom of a glass of water and very old eggs will float to the top. The float test does not reveal whether an egg is safe to eat! A freshly collected egg from a dirty nest box can harbor Salmonella yet sink to the bottom of a glass; conversely, an egg that floats is old, but may be safe to eat.
Between the eggshell and the egg white are two membranes that provide additional layers of defense against microbes. Just before an egg is laid, the outer and inner membranes adhere closely to the shell and each other. When the egg is laid, the membranes begin to pull away from the shell, creating an air cell that gets bigger as the egg ages. The more air, the better the egg floats. (Incidentally, this air cell serves as a small oxygen reservoir for a chick just prior to hatching.)
With found eggs, I feel it’s better not to eat them than to play Salmonella roulette with human health. I have had Salmonella poisoning from commercially produced meat and strongly recommend against visiting Salmonellatown. Besides, I know that whenever I throw out an egg of unknown safety, my hens are already hard at work making more.
The essence of the float test is that newly laid eggs will lay flat on the bottom of a glass of water and very old eggs will float to the top. The float test does not reveal whether an egg is safe to eat! A freshly collected egg from a dirty nest box can harbor Salmonella yet sink to the bottom of a glass; conversely, an egg that floats is old, but may still be safe to eat.
When a hen is sexually mature, lighting conditions stimulate hormones that cause her ovary to release a yolk into the oviduct where it acquires the albumen (whites), membranes, and shell (including shell color). The process takes approximately 23–25 hours. Within about 30 minutes of an egg being laid, the process starts again.
Drop in Egg Production?
Fluctuations in egg production can be caused by myriad physical, behavioral, environmental, and emotional triggers. Some point to a problem; others are normal and expected. To determine the reason for a decline in egg production, a complete flock history and physical assessment of all birds should be performed, asking questions such as: Have any new chickens been added to the flock? Were new birds properly quarantined? Have there been any changes in feed, housing arrangements, weather, lighting, or droppings? Have there been any signs of predators or sickness? After taking all factors into consideration, the cause should become apparent.
A drop in egg production can be a first sign of a problem in the flock. Just as we pay attention to our chickens’ droppings to monitor their health, we should observe daily egg count for signs of trouble. Here are some of the most common causes of a drop in egg production in backyard flocks, with possible solutions:
Decreased lighting conditions. Light triggers a hen’s pineal gland to produce eggs. Regular egg laying requires 14 to 16 hours of light; decreased daylight hours in autumn and winter can cause a drop (or stop) in egg production. Supplemental light can be added to the coop to encourage egg laying with no detrimental effects to the hen, despite myths to the contrary.
Molting. The annual replacement of feathers coincides with the regression of a hen’s reproductive tract and the diversion of resources away from egg production to feather growth.
Change and stress. Stress puts the brakes on egg production. Stressors can include changes in feed or coop layout, moving to a different farm or coop, adding or losing flock members, harassment from a predator, irritation from internal or external parasites and pests, violent weather, barking dogs, and temperature extremes.
Broodiness. Broody hens stop laying eggs to incubate and hatch chicks. A broody hen’s presence in the coop can inspire a chain reaction of broodiness. Broodies should be broken properly or permitted to hatch eggs away from the nest boxes.
Disease, illness, and parasites. Hens do not perform optimally when they are sick or are infested with parasites. Look at a drop in egg production in conjunction with other flock symptoms or conditions.
Age. After 2 years, a hen’s best egg-laying years are behind her and production continues to decline as time marches on. Nothing can reverse this process.
Nutritional deficiency. Hens cannot produce eggs optimally without the right diet. The wrong feed, too many snacks (even healthy food extras), unnecessary supplements, or being prevented from getting to the feeder by flockmates can interfere with proper nutrition and egg production.
Water deprivation. Water is imperative to the formation of eggs. Egg production will suffer if a hen’s access to water is limited physically by being frozen, too far away, or unpalatable (medicated or too warm) (see chapters 7 and 9).
Reproductive dysfunction. Disease or malfunctions of the oviduct such as egg binding and internal laying can cause a decline in egg production. Seek veterinary help for a hen that has a swollen, squishy, water-balloon-like abdomen or if signs of egg-looking junk are found (see “Salpingitis and Lash Eggs: ‘The Pus Coagulegg’”).
Sometimes a drop in eggs isn’t a drop in production at all … more like missing eggs:
A drop in egg production can be the first sign of a problem in the flock.
Egg hiding. Free-range or pasture-raised hens may get into the unwelcome habit of laying eggs outside the coop in secluded locations. Hens have been known to disappear for weeks and return to the flock with baby chicks in tow! Coop training ordinarily eliminates the problem of egg hiding (see chapter 10).
Egg eating. Everyone loves fresh eggs, and chickens are no exception. Hens often start eating eggs when they discover a broken egg in a nest box. Once a chicken gets a taste, it becomes difficult to deter intentional egg breaking and eating (see chapter 10).
Predator theft. Sometimes fewer eggs can be attributed to theft by predators like rats, snakes, or opossums (see chapter 3).