Page 533 - Anatomy and Physiology of Farm Animals, 8th Edition

518 / Anatomy and Physiology of Farm Animals

• Describe the events leading to egg laying, separate superorder of flightless birds,
from the anatomy of the female reproduc-
Ratitae. Table 30‐1 lists terms commonly
VetBooks.ir tive tract to the endocrinology associated used for poultry of different genders, ages,
with ovulation and oviposition.
and reproductive status.
Studies of domestic chickens are the
basis for most of the avian physiology in
he term poultry refers to domesti- this chapter, and much of this information
Tcated birds used for the production of (e.g., urinary excretion of uric acid, basics
meat and eggs. Chickens are the most of respiratory function) could be applied to
common poultry worldwide, followed by all birds. However, turkeys and chickens
turkeys in the United States and ducks and raised by producers in the United States
geese elsewhere. Because poultry can be have been derived by intense genetic
maintained in a relatively small space and selection for egg and/or meat production,
are extremely efficient in converting plant and these domesticated birds have some
protein to animal protein, they are a sig- anatomical and physiological characteris-
nificant source of animal protein in devel- tics that are quite different from their wild
oping countries, as well as the rest of the ancestors. For example, almost all breeding
world. In the United States, commercial of domestic turkey hens is done by artifi-
poultry are primarily housed in large facili- cial insemination because of the poor
ties under closely regulated environments. breeding performance of the male domes-
Elsewhere, poultry are often raised in small tic turkey.
groups in close proximity to humans and
other animals. Under such circumstances,
poultry can be an important source of Integument
zoonotic diseases.
The domestic chicken (Gallus gallus or The skin of poultry is similar to mammalian
Gallus domesticus) and turkey (Meleagris skin in that it is an organ composed of an
gallopavo) are in the order Galliformes, overlying stratified squamous epithelium
whereas domestic ducks (e.g., Anas platy- and the underlying vascular dermis. Avian
rhynchos [mallard duck] and Cairina skin is typically very thin. It lacks sweat
moschata [Muscovy duck]) and geese glands entirely. Most of the skin is not par-
(e.g., Anser anser [domestic greylag ticularly well vascularized, but in birds incu-
goose] and Anser cygnoides [swan goose]) bating eggs brooding patches may develop
are Anseriformes. All are in the superorder, on the breast. In these areas, the skin thick-
Carinatae. In this chapter, the term galli- ens, becomes more vascular, and feathers
naceous will refer to chickens and turkeys, are lost. The brooding patch provides the
and fowl will refer to all domesticated incubating eggs with intimate contact with
birds. The emu, rhea, and ostrich are in a the warm skin of the parent bird.

Table 30-1. Terms Commonly Used for Domestic Fowl
Species Male Female Juvenile Other
Chicken Rooster or cock Hen Chick Capon – castrated male
Cockerel – immature male
Pullet – immature female
Turkey Tom Hen Poult
Duck Drake Hen or duck Duckling
Goose Gander Goose Gosling
Swan Cob Pen Cygnet