Poultry Science Terminology - U

Ulcer: raw, inflamed, and open red sore. Often caused by an irritation to the surface of the skin or lining of the digestive system

Undercolor: color of the down part of the plumage

Undergrade: edible shell eggs that do not meet the requirements (standards) for Grade AA, Grade A, Grade B, or Checks

United States Department of Agriculture (USDA): government agency that regulates agricultural and food products

Unsexed: day-old chicks that have not been sorted by sex (also called straight-run) 

Unthrifty: unhealthy appearing and/or failing to grow at a normal rate

Urates: uric acid (the avian form of salts found in urine) 

Uremia: poisoning caused by accumulated wastes in the body, typically due to kidney failure 

Urolith: urinary stone

Uropygial gland: large oil gland on the back and at the base of the tail of birds providing oil for the birds to preen their feathers (also called the preen or oil gland) 

Uterus: 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 (egg shell synthesis); known as the shell gland

Utility Breeds: traditional "barnyard" birds, bred for a combination of egg laying abilities and meat production capabilities. These are all-purpose breeds



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