An udder is an organ formed of the mammary glands of female quadruped mammals, especially ruminants such as cattle, goats, sheep and deer.

The udder is a single mass hanging beneath the animal, consisting of pairs of mammary glands. In cattle there are normally two pairs, in sheep, goats and deer there is one pair, and in some animals such as pigs there are many pairs.

Udder care and hygiene in cows is important in milking, aiding uninterrupted and untainted milk production, and preventing mastitis. Products exist to soothe the chapped skin of the udder.


Ulceration may refer to:

– Ulcer (dermatology), a discontinuity of the skin
– Oral ulcer, an open sore inside the mouth
– Aphthous ulcer, a specific type of oral ulcer also known as a canker sore
– Peptic ulcer, a discontinuity of the gastrointestinal mucosa (stomach ulcer)
– Corneal ulcer, an inflammatory or infective condition of the cornea
– Venous ulcer, a wound thought to occur due to improper functioning of valves in the veins
– Genital ulcer, an ulcer located on the genital area


Urea or carbamide is an organic compound with the chemical formula (NH2)2CO. The molecule has two amine (-NH2) residues joined by a carbonyl (-CO-) functional group.

Urea serves an important role in the metabolism of nitrogen-containing compounds by animals and is the main nitrogen-containing substance in the urine of mammals. Being solid, colourless, odorless, neither acidic nor alkaline, highly soluble in water, and relatively non-toxic, urea is widely used in fertilizers as a convenient source of nitrogen. Urea is also an important raw material for the chemical industry. The synthesis of this organic compound by Friedrich Wöhler in 1828 from an inorganic precursor was an important milestone in the development of chemistry.

The terms urea and carbamide are also used for a class of chemical compounds sharing the same functional group RR’N-CO-NRR’, namely a carbonyl group attached to two organic amine residues. Example include carbamide peroxide, allantoin, and hydantoin. Ureas are closely related to biurets and related in structure to amides, carbamates, diimides, carbodiimides, and thiocarbamides.


Weaning is the process of gradually introducing a mammal infant, either human or animal, to what will be its adult diet and withdrawing the supply of its mother’s milk.


An egg yolk is a part of an egg which feeds the developing embryo. The egg yolk is suspended in the egg white (known more formally as albumen or ovalbumin) by one or two spiral bands of tissue called the chalazae. Prior to fertilization, the yolk together with the germinal disc is a single cell; one of the few single cells that can be seen by the naked eye.

As a food, yolks are a major source of vitamins and minerals. They contain all of the egg’s fat and cholesterol, and almost half of the protein.

If left intact while cooking fried eggs, the yellow yolk surrounded by a flat blob of whites creates the distinctive sunny-side up form of the food. Mixing the two components together before frying results in the pale yellow form found in omelettes and scrambled eggs.


Zinc, also known as spelter, is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2. Zinc is the 24th most abundant element in the Earth’s crust and has five stable isotopes. The most exploited zinc ore is sphalerite, a zinc sulfide.

Zinc is an essential mineral of “exceptional biologic and public health importance”.


A zoonosis or zoonose is any infectious disease that can be transmitted (in some instances, by a vector) from non-human animals, both wild and domestic, to humans or from humans to non-human animals (the latter is sometimes called reverse zoonosis). Many serious diseases fall under this category.

The simplest definition of a zoonosis is a disease that can be transmitted from other vertebrate animals to humans. A slightly more technical definition is a disease that normally infects other animals, but can also infect humans. The reverse situation (transmission from human to animal) is known as anthroponosis.

The emerging interdisciplinary field of conservation medicine, which integrates human and veterinary medicine, and environmental sciences, is largely concerned with zoonoses.