Definitions Relating to Poultry
Incubation and Embryology Projects
Classification | Anatomy | Avian
Egg | Incubation & Embryology
Words about the classification of chickens
- Avian - Of, relating to, or
characteristic of birds; derived from birds.
- Bantam - A small miniature chicken,
usually one-fourth to one-fifth the size of regular chickens; frequently
called "bantie." Most, but not all, bantams are the likeness of a
larger variety of domestic chickens.
- Breed - A group of chickens within a
class having a distinctive body shape and the same general features and
- Broiler or fryer - A young meat-type
chicken, usually 9 to 12 weeks of age, of either sex, that can be cooked
tender by broiling or frying, usually weighing between 2 1/2 and 3 1/2
- Class - A group of chickens that has
been developed in a particular region of the world.
- Cock - A male chicken over one year of
age; also called cock bird and old rooster.
- Cockerel - A male chicken under one
year of age; also called young rooster.
- Crossbred - The offspring of parents
of different varieties or breeds.
- Gallus domesticus - The
- Gallus gallus - The Red Jungle
Fowl; also called gallus bankiva.
- Genus - A group of closely related
animals or plants which differ from one another in only slight
- Hen - A female chicken over one year
- Inbred - The offspring of closely
related parents; resulting from inbreeding.
- Incrossbred - The offspring from
crossing inbred parents of the same or different breeds.
- Layers - Mature female chickens kept
for egg production; also called laying hens.
- Pullet - A female chicken under one
year of age.
- Purebred - The offspring of purebred
parents that are of the same class, breed, and variety.
- Roaster - A young meat-type chicken,
usually 3 to 5 months of age, of either sex, that can be cooked tender by
roasting, and usually weighing 4 pounds or over.
- Sexed chickens - Day-old chicks with
the males and females separated.
- Started pullets - Female chickens that
are partially grown, usually to point of lay that is about 20 weeks of age,
by specialized growers for sale to egg farmers.
- Straight-run chicks - Day-old chicks
that have not been separated according to sexes.
- Strain - A group of birds within a
variety that has been bred by one person or firm for some time and has more
or less uniform characteristics and capabilities.
- Strain cross - The offspring of
parents of two or more different strains belonging to the same variety.
- Stewing chicken - A mature female
chicken, usually more than 10 months of age; that requires moist,
pressurized, or extended cooking; also called hen or fowl.
- Variety - A subdivision of a breed,
distingushed by color, color pattern, or kind of comb.
Words about the anatomy of chickens
- Beak - The bird's bill; the protruding
mouthpart of a bird.
- Cloaca - The vent or common opening in
birds through which the intestinal, urinary, and reproductive tracts empty.
- Comb - The fleshy, red outgrowth on
top of a chicken's head; there are eight types of combs.
- Earlobes - The fleshy patch of bare
skin below the ears varying in size and shape with the color red, white,
blue, or purple, according to the breed.
- Gizzard - An internal organ of birds.
It has thick muscular walls and a tough lining. It crushes and grinds foods
by muscular action and with pebbles or grit.
- Infundibulum - The funnel end of the
oviduct that picks up the yolk when it is released from the ovary; the area
in which fertilization of the true egg takes place; also called funnel.
- Isthmus - The section of the oviduct
next to the magnum where the water and mineral salts are deposited and the
inner and outer shell membranes are formed.
- Magnum - The section of the oviduct
next to the infundibulum; the area in which the thick white is deposited and
the shape is formed.
- Ovary - The organ of the female which
holds the true eggs and produces the yolks on which the true eggs are
- Oviduct - The organ of the female
birds that puts the albumen, shell membranes, and the shell of the avian egg
around the yolk.
- Ovum - The female germ cell; plural
form is ova.
- Pituitary gland - A small
kidney-shaped gland located at the base of the brain that produces hormones
involved in sexual maturity, the maturation and release of yolks, and egg
- Uterus - The section of the oviduct
next to the isthmus where final portions of the white and minerals are
deposited and shell and shell pigment are added.
- Vagina - The section of the oviduct
next to the uterus in which the cuticle is deposited on the shell and the
eggs are turned completely around on its long axis so that the large end is
- Wattles - The fleshy, red growths that
hang from the side and base of the chicken's beak.
- Yolk sac - The follicle where an ovum
and its surrounding yolk are held until the yolk matures and is released.
Words about the avian egg
- Air cell - The air space between the
two shell membranes, usually at the large end of the egg, that can be
plainly seen when an egg is candled.
- Albumen - The white of an egg,
consisting of outer thin, firm, inner thin, and chalaziferous layers.
- Avian egg - The mass of material
constituting the bird egg - the shell, shell membranes, albumen, and yolk -
that is designed by nature to nourish and protect the true egg.
- Blastoderm - A fertilized true egg.
- Blastodisc - A true egg that was not
- Chalazae - The two whitish cords on
opposite sides of the yolk that hold the yolk in the center of the albumen
and serve as a rotating axis to keep the germ cell on the top side of the
yolk and next to the heat of the hen's body.
- Cuticle - A secretion of the uterus
consisting mainly of protein that serves to partially seal the pores in the
egg's shell and acts as a lubricant when the egg is laid; commonly called
- Egg - The microscopic cell of the
female; the true egg; the female germ cell.
- Fertile - An egg that is fertilized;
the capability of an egg to develop into a chick.
- Fertilization - The act or process of
making or becoming fertile; the union of a male cell with a female cell.
- Infertile - An egg that is not
fertilized, will not hatch.
- Shell - The hard outer surface of an
egg made up largely of calcium carbonate; the shell has pores allowing loss
of carbon dioxide and moisture from the egg.
- Shell membranes - Two thin membranes
next to the shell and surrounding the albumen and yolk; known as inner and
outer shell membranes; they are one of the egg's chief defenses against
- Sperm - The microscopic cell of the
male; the male germ cell.
- Yolk - The round yellow mass upon
which the true egg is located and that provides nutrients for the developing
Words about incubation and embryology
Compiled by S. F. Ridlen, Poultry Extension Specialist,
University of Illinois at Urbana-Champaign
- Allantois - A sac connected to the
emrbyo's abdomen making respiration by the embryo possible; it also stores
excretions, absorbs albumen used for food by the embryo, and absorbs calcium
from the egg shell for the structural needs of the embryo.
- Amnion - A transparent sac, filled
with colorless fluid, surrounding the embryo; the amnion and amniotic fluid
protect the developing embryo from shock and permit it to exercise.
- Broody hen - A hen that through
hormonal changes has undergone marked changes in behavior and physiology,
including cessation of laying and development of the maternal instincts. A
hen that wants to sit on eggs to hatch them and to brood chicks.
- Chick tooth - A tiny, sharp, horny
projection on the end of the chick's beak used by the chick to peck holes in
the shell. Also known as egg tooth.
- Chorion - A membrane that surrounds
both the yolk sac and the amnion; it has no apparent initial function but
later fuses with the allantois to form the chorio- allantois membrane.
- Down - Soft, fine, hair-like feathers
on young birds.
- Embryo - The developing chick within
- Embryology - The study of the
formation and development of embryos.
- Extra embryonic membranes - Membranes
outside the embryo's body that make respiration, nutrition, and secretion
possible and provide protection; they include the yolk sac, amnion,
allantois, and chorion.
- Fertility - The quality or state of
- Hatchability - The quality or state of
- Humidity - The amount of moisture in
the air in the incubator; 50 to 55 percent relative humidity is ideal the
first 18 days of incubation and about 65 percent the last three days.
- Incubation - The process of applying
heat, either naturally or artificially, to eggs to cause them to hatch.
- Incubator - An artificially heated
container for hatching eggs. In a still-air incubator the air is not
circulated mechanically. Forced-air incubators have a fan or fans to
circulate the air.
- Pip - To break through or peck holes
in the shell by the chick.
- Primitive streak - A vertical, opaque
line where the embryo begins to grow and develop.
- Set - To put eggs under a broody hen
or in an incubator to hatch them.
- Temperature - The level of heat in the
incubator; can vary from 99 degrees to 103 degrees F. 100.5 degrees F is
optimum for a still-air incubator.
- Turn - The act of changing the
position of eggs being incubated to prevent the embryos from sticking to the