Egg Terms

Curious about egg production lingo? Click on a term to learn what it means.

For more terms on nutrition and use of eggs, see the Incredible Edible Egg™ Eggcyclopedia.


American Egg Board

American Egg Board (AEB) is the promotion (advertising, marketing communications), education and research organization for the U.S. egg industry. The activities of AEB are conducted under the oversight of the U.S. Department of Agriculture (USDA). The Secretary of Agriculture appoints a Board of Directors, egg producers who provide direction to administer the program on behalf of all egg producers in the 48 contiguous states. The Board was authorized by the Egg Research and Consumer Information Act passed by the 93rd Congress. The purpose of the law is “to enable egg producers to establish, finance and carry out a coordinated program of research, producer and consumer education and promotion to improve, maintain and develop markets for eggs and egg products.”

Animal welfare audits

On-farm assessments that are conducted by independent, third-party organizations as part of a certification program to assure that animals are being raised according to set animal care guidelines. For laying hens, UEP Certified is one such science-based certification programs, with guidelines for conventional housing established in 2002 and cage-free guidelines launched in 2006.

See also UEP Certified

Antibiotic-free eggs

Eggs can be labeled as antibiotic-free if egg farmers choose not to use any antibiotics in feed or water, when the pullets (young hens) are growing or when hens are laying eggs. Certified organic eggs must be antibiotic-free by regulation.

See also Antibiotics, Organic eggs


Antibiotics are drugs that fight infections caused by bacteria. Due to on-farm disease prevention and effective use of vaccines, only a small percentage of egg-laying hens receive antibiotics. If they do, it is under supervision of a veterinarian and only for a short time to treat a specific disease or prevent a recurring disease. A limited number of FDA*-approved antibiotics are available for egg farms, provided they comply with FDA guidelines for usage. These FDA regulations also are designed to assure antibiotic residues are not passed to eggs.

(*FDA=Food and Drug Administration)

See also antibiotic-free eggs.

Avian Influenza

Avian influenza (AI), also referred to as bird flu, is a virus that infects all types of avian species, including wild birds and domestic poultry. AI is an animal health issue that causes mild to severe symptoms in birds and, in its most extreme form, can be fatal to infected birds.

The U.S. egg industry has had years of experience dealing with AI in commercial poultry flocks. Egg farmers work closely with the U.S. Department of Agriculture (USDA) in these efforts and are well-equipped to identify AI outbreaks quickly and eradicate them immediately.

Humans cannot get AI through eating thoroughly-cooked eggs as proper cooking easily destroys all AI virus particles. The USDA, the Food and Drug Administration and the World Health Organization all agree that properly-cooked eggs are safe to eat. Cook basic egg recipes until the yolk and white are firm and cook or bake any dishes containing eggs until they reach 160℉.


A cage-free housing design that allows hens to roam and move back and forth to different levels. Hens can forage and dust bathe in an open area, and move up to nest boxes on an upper level. This system requires more than twice as much space to produce the same numbers of eggs as a conventional cage system.

See also Nest / Nesting / Nest boxes


Beak trimming

The old phrase “pecking order” comes from the fact that chickens do peck at one another, sometimes inflicting considerable injury and even death. To prevent this, the majority of commercial egg farms trim beaks when chicks are 10 days of age or younger, when there is little stress, a practice supported by the scientific community. The process is similar to clipping a dog’s nails or trimming a horse’s hooves. Chicks and hens with trimmed beaks can still eat and drink normally. Research has shown that mortality in flocks that are not beak-trimmed is considerably higher than in flocks that are beak-trimmed.

See also Pecking order


Biosecurity practices are intended to protect harmful biological agents from entering a flock of birds. Common examples include limiting poultry building access only to necessary personnel and preventing wild birds, rodents, pets and other animals from mixing with the flock.

Bird flu – See Avian Influenza


Processors who convert shell eggs into liquid or further-processed egg products. Breaking plants are under strict U.S. Department of Agriculture (USDA) inspection by USDA’s Food Safety and Inspection Service. Breaking plants use a fascinating array of modern equipment to break eggs and separate the shell, white and yolk.


The breed of hen determines the color of the shell. Among commercial breeds, hens with white feathers and ear lobes lay white-shelled eggs; hens with red feathers and ear lobes lay brown eggs. White eggs are most in demand among American buyers. In some parts of the country, however, particularly in New England, brown shells are preferred. Commercial brown-egg layers are hens derived from the Rhode Island Red, New Hampshire and Plymouth Rock breeds. Since brown-egg layers are slightly larger birds and require more food, brown eggs are usually more expensive than white.

See also Brown eggs, Color (egg shell)

Brown eggs

Shell color comes from pigments in the outer layer of the shell and, in eggs from various commercial breeds, may range from white to deep brown. The breed of hen determines the color of the shell. Among commercial breeds, hens with white feathers and ear lobes lay white-shelled eggs; hens with red/brown feathers and ear lobes lay brown eggs.

See also Breed, Color (egg shell)


Cage-free eggs

Cage-free eggs are laid by hens that are able to roam vertically and horizontally in indoor houses, and have access to fresh food and water. Cage-free systems vary from farm-to-farm, and can include multi-tier aviaries. They must allow hens to exhibit natural behaviors and include enrichments such as scratch areas, perches and nests. Hens must have access to litter, protection from predators and be able to move in a barn in a manner that promotes bird welfare.


Candling is the step during grading when the egg grader looks inside the egg (without breaking it) to judge quality. Long ago, this quality check was done by holding a candle behind an egg. Some hand-candling, using electric equipment, is still used for spot-checking or for training egg graders; however, today most eggs pass on rollers over high-intensity lights that make the interior of the egg visible. The eggs are rotated so all parts are visible. The candler checks the size of the air cell and the distinctness of the yolk outline. Imperfections such as blood spots usually show during candling. Very large packing plants may also use electronic blood and/or check detectors to sort and remove eggs exhibiting these defects.

See also Grading, Processing

Carton dates

Egg cartons from plants producing U.S Department of Agriculture (USDA)-graded eggs must display a Julian date – the date the eggs were packed. Although not required, egg cartons may also carry an expiration (sell-by) date and/or a best-by (use-by) date. Expiration dates are included on some egg cartons ensuring retailers do not keep eggs on shelves past a certain date. However, eggs can be safely eaten 2 to 3 weeks beyond the expiration date. Depending on the state, the expiration date may be labeled as SELL BY, USE BY, EXP BY or BEST BY. On USDA grade-shielded egg cartons, if an expiration date appears, it can be no more than 30 days after the pack date. It may be less than 30 days through the choice of the packer or quantity purchaser, such as your local supermarket chain. On USDA grade-shielded egg cartons, if a best-by (use-by) date appears, it can be no more than 45 days after the pack date. Eggs that are not packed under USDA's grading program must be labeled and coded in accordance with egg laws in the state where they are packed and/or sold. Most states require the use of a Julian date.

See also Expiration date, Julian date

Coalition for Sustainable Egg Supply (CSES)

A multi-stakeholder group of animal welfare scientists, academic institutions, non-government organizations, egg suppliers and restaurant/foodservice and food retail companies. CSES evaluated various laying hen housing environments and found benefits and trade-offs with each type of housing. Refer to CSES website.

Color (egg shell)

Shell color comes from pigments in the outer layer of the shell and may range from white to deep brown. The shell color has no relationship to egg quality, flavor, nutritive value, cooking characteristics or shell thickness. The color is determined by the breed of hen that laid the egg. Among commercial breeds, hens with white feathers and ear lobes lay white-shelled eggs; hens with red feathers and ear lobes lay brown eggs. Since brown-egg layers are slightly larger birds and require more food, brown eggs are usually more expensive than white.

See also Breed, Brown eggs

Conventional cage housing

A type of housing introduced in the 1950s to protect flocks from weather, predators and disease. Farmers found that cages also improved sanitation and allowed for more efficient production. Hens are kept in smaller groups, which can minimize aggression and pecking order. Hens have continuous access to feed and water and are able to move about within the cage.



Euthanasia of many hens on a farm to prevent the spread of disease or for older hens with decreased egg production. When depopulation is necessary, best management practices support only those approved methods that are instantaneous and painless.

See also Euthanasia


Egg belt

A conveyer system inside poultry houses that carries eggs away from barns after they are laid to be cleaned and processed for transport to retail outlets.

See also Inline processing

Egg Products Inspection Act

The Egg Products Inspection Act assures that eggs and egg products distributed and consumed by the public are wholesome, not adulterated, and properly labeled and packaged. Passed by Congress in 1970, the Egg Products Inspection Act is administered by the United States Department of Agriculture (USDA) and imposes specific inspection requirements for two categories of eggs – shell eggs and egg products.

Under the Egg Products Inspection Act, plants that break, dry and process shell eggs into liquid, frozen or dried egg products must operate under the continuous inspection program of the USDA. (The law does not apply to food-manufacturing plants which prepare cooked eggs or other food products made with eggs or egg products, such as those which make mayonnaise, egg noodles and ice cream, for example.) An official inspector must be present at all times when eggs are being processed.

Egg Safety Rule

An FDA rule implemented in 2010 to enhance egg safety by requiring measures to prevent the bacterium Salmonella Enteritidis (SE) from contaminating eggs on the farm and reduce further growth during storage and transportation. On farms of 3000 hens or more, the Egg Safety Rule requires farms take certain preventive steps while producing eggs on the farm and mandates refrigeration during storage and transportation.

Enriched colony housing

This housing provides a larger enclosed space that is equipped with perches, private nesting areas and a surface to facilitate natural behaviors such as foraging and dust bathing. Sometimes referred to as furnished housing.


Humanely ending the life of an animal that has an incurable and painful disease. When euthanasia of a chick or grown bird is necessary, best management practices support only those veterinarian-approved methods that are instantaneous and painless.

See also Depopulation

Expiration Date

A date on an egg carton beyond which the eggs should not be sold.


Fertile eggs

Fertilized eggs can be found at specialty foods stores. Commercially-raised eggs are laid by hens who have not mated with a rooster so are not fertilized.

Floor space

The amount of floor space available to each hen within an indoor house. Depending on the housing style, UEP Certified guidelines require that a minimum range of 1.0 - 1.5 square feet of usable floor space per hen be provided to allow for normal behavior.


On these farms, hens have some access to the outdoors. There are not specific guidelines for free-range egg production, and farms are not required to use third-party audits.

Further processing

Out-of-the-shell eggs are combined with other ingredients to create finished food products for retail and foodservice users. Further processed egg products are classified into four groups: refrigerated liquid egg products; frozen and cooked egg products; dried egg products and non-food byproducts. Further processed eggs are commonly called “egg products.”



Classification determined by the interior and exterior quality of the egg at the time it is packed. In some egg-packing plants, the U.S. Department of Agriculture (USDA) provides a voluntary grading service for shell eggs. The official USDA grade shield on an egg carton certifies that the eggs have been processed, packaged and certified under federal supervision according to the U.S. Standards, Grades and Weight Classes for Shell Eggs established by USDA. Plant processing equipment, facilities, sanitation and operating procedures are continuously monitored by the USDA egg grader. In the grading process, eggs are examined for both interior and exterior quality before they’re sorted according to weight (size). Grade quality and weight (size) are not related to one another. Eggs of any quality grade may differ in weight (size). In descending order of quality, grades are designated AA, A and B.

See also Candling, Processing



In the U.S., by federal law passed more than 50 years ago, neither laying hens nor any other type of poultry can be fed hormones. However, eggs contain natural hormones. Therefore, the statement “no hormones” is considered misleading to the consumer. The egg industry does not use added hormones in the production of shell eggs. The FDA requires a qualifying statement on the label for shell eggs, which is “Hormones are not used in the production of shell eggs.”


Inline processing

In inline processing, processing of eggs occurs at the same location that they are laid, as opposed to offline processing, during which eggs are transported to an off-farm location. Inline processing is the most efficient egg collection and processing system, as the eggs are delivered from the farm to the egg processing facility by an enclosed conveyer system.

See also Egg belt

Inline processing

In inline processing, processing of eggs occurs at the same location that they are laid, as opposed to offline processing, during which eggs are transported to an off-farm location. Inline processing is the most efficient egg collection and processing system, as the eggs are delivered from the farm to the egg processing facility by an enclosed conveyer system.

See also Egg belt


Julian Dates

Starting with January 1 as 001 and ending with December 31 as 365, these numbers represent the consecutive days of the year. This number system is sometimes used on egg cartons to denote the day the eggs are packed. You can store fresh shell eggs in their cartons in the refrigerator with insignificant quality loss for four to five weeks beyond this date.

See also Carton dates


Layer / Laying hen

A grown, female chicken kept primarily for laying eggs.


Manure belts / belt system

Conveyer systems inside poultry houses that aid in the drying of manure, reduce pests and odors, and carry manure away from the birds and eggs to a storage facility outside the barn.

Manure management

Capturing, drying, storing, treating and utilizing poultry manure in an environmentally-responsible manner.


This process of shedding old feathers to make way for new growth causes hens to lay fewer (or no) eggs. On commercial farms, induced molting allows farmers to bring all hens into a molt at the same time, which allows improved egg quality and more efficient egg production. UEP guidelines stipulate only non-feed withdrawal molt methods be used.


National Poultry Improvement Plan (NPIP)

The National Poultry Improvement Plan provides a cooperative industry, state, and federal program using diagnostic technology to improve poultry and poultry products. Refer to NPIP website.


The U.S. Department of Agriculture (USDA) identifies all shell eggs as natural.

Nest / Nesting / Nest boxes

Nests separated with curtains are provided in cage-free and enriched colony housing to allow hens privacy for egg-laying, to facilitate egg collection, to minimize the risk of cannibalism and for food safety and sanitary reasons.

Nest-run eggs

Eggs which are packed as they come from the production facilities without having been washed, sized and candled for quality.


Organic eggs

Eggs produced according to national U.S. Department of Agriculture (USDA) organic standards related to methods, practices and substances used in producing and handling crops, livestock and processed agricultural products.

All organic eggs are from free-range hens and must meet all of the requirements for those, including being raised outdoors or having access to the outdoors as weather permits.

Among other requirements, organic eggs are produced by hens fed rations having ingredients that were grown without most conventional pesticides, fungicides, herbicides or commercial fertilizers. While growth hormones are also prohibited, no commercial laying hen rations (whether organic or not) ever contain added hormones. Due to higher production costs and lower volume per farm, organic eggs are more expensive than eggs from hens fed conventional feed. The nutrient content of eggs is similar, whether the hens eat organic or conventional feed.

See also Antibiotic-free eggs, Free-range eggs


Pasteurized eggs

A process during which liquid and further processed eggs are heated to temperatures just below the coagulation point to destroy pathogens, which may be beneficial for immune-compromised individuals.


Hens in this type of management system have access to the outdoors and graze primarily by eating grass and bugs. There are not specific guidelines for pasture-raised egg production, and farms are not required to use third-party audits.

Pecking order

The old phrase “pecking order” comes from the fact that chickens do peck at one another, sometimes inflicting considerable injury and even death. Egg farmers work to minimize pecking order and protect hens from one another through choices in hen care, housing environment and flock management.

See also Beak trimming


Perches are designed within some indoor housing environments to allow hens living in large flocks to roost comfortably with a minimum of disturbance, to provide hens with a refuge from injurious pecking and to minimize flightiness.


Egg processing involves:

  • Washing to remove contaminants such as manure and blood
  • Removing eggs with abnormal shapes or other defects
  • Holding eggs to a concentrated light (candling) to identify internal defects
  • Grading according to characteristics such as quality and weight
  • Packaging to ensure safe shipment and enhanced product appearance
  • Labeling with the Plant Code, as well as Packing and Sell By dates
  • Including other relevant labels, like nutritional facts, a “keep refrigerated” advisory and the UEP Certified logo
  • Storing in refrigeration prior to transport
  • Transporting from the farm at a temperature of 45˚ F

See also Candling, Grading, Inline processing, Further processing


A young female chicken less than 1 year old. For egg layers, a pullet is a young female before she reaches sexual maturity and starts laying eggs, around 17 to 18 weeks.



Nourishment for egg-laying hens must be formulated and fed to promote good health and normal production. To minimize the risk of bone fractures, laying hens should be able to consume enough calcium and phosphorus daily to support eggshell formation without loss of structural bone.



A group of bacteria found in the intestinal tracts of animals, birds, reptiles, insects and humans. The majority of reported salmonellosis outbreaks involving eggs or foods that contain eggs have occurred in food service kitchens and resulted from inadequate refrigeration, improper handling and/or insufficient cooking. The egg community follows several programs to reduce Salmonella bacteria and produce safe eggs.

Scientific Advisory Committee

A panel commissioned by United Egg Producers in 1999 to review scientific literature on specific topics relevant to the well-being of laying hens and to identify areas where further research was needed. This process led to the development and implementation of science-based guidelines (UEP Certified) to improve the well-being of laying hens managed in conventional and cage-free production systems.


UEP 5-Star Egg Safety Program

A voluntary program of United Egg Producers. “5-Star” goes beyond the FDA* Egg Safety Rule requirements to provide egg farmers with a comprehensive, dependable food safety program from the farm through processing.

(*FDA = Food and Drug Administration)

UEP Certified

Developed by United Egg Producers and voluntarily implemented by egg farmers in 2002, this program outlines science-based guidelines for the care and well-being of hens. Any egg farm wanting to market eggs as UEP Certified must implement the scientific guidelines on 100 percent of their flocks. An independent, third-party audit program assures that each farm complies with the guidelines. The UEP Certified logo signifies eggs originate from farms dedicated to responsible, science-based practices to ensure optimal hen care.

See also Animal welfare audits

United Egg Producers

United Egg Producers (UEP) is a cooperative of U.S. egg farmers working collaboratively to address legislative, regulatory and advocacy issues impacting the industry through active farmer-member leadership, a unified voice and partnership across the agriculture community. UEP’s farmer-members work to provide for the health and well-being of their birds; to produce safe, nutritious, high-quality eggs; and to manage their farms responsibly with best on-farm management practices. Formed in 1968, UEP members represent 90 percent of US egg production.



Washing eggs removes any dirt or stains. In modern layer houses, eggs are gathered shortly after they’re laid and moved to automated washing equipment. Strict federal regulations specify the procedures and food-safe cleaning compounds that may be used. Today most eggs are cleaned in mechanical egg washers employing sprayers, brushes, detergent-sanitizers, rinsers and driers. Only clean eggs go to the market. In washing, the bloom is removed, so eggs are immediately refrigerated on the farm after washing to reduce growth of bacteria.

See also Processing