* The major waste product eliminated from protein catabolism.
* It contains some nitrogen (28-45%) and makes the urinous smell.
Creatinine
* A muscular waste generated from creatine metabolism.
* It is secreted by the kidneys with no reabsorption.
* It is directly related to muscle mass.
Uric Acid
* It contains much more nitrogen (70-80%) and is found in bird and reptile urine.
* It is an exclusive of animal urine.
* Some mammals like human and dalmatian dogs can form it to small extent.
Ammonia
* In animals like cattle, and sheep more urea undergoes bacterial decomposition yielding ammonia.
* It is highly irritating to the nasal mucosa and mucous membranes of the eyes.
* It is converted to urea in the liver through process known as urea synthesis to prevent its toxic effect.
Others
* Sodium
* Calcium
* Potassium
* Magnesium
* Chloride