Application of urea in ruminants.
Non-protein nitrogen feed refers to the general term for urea, bicosal and certain amine salts. They are simple nitrogen-containing compounds synthesized by chemicals and do not provide energy. According to the metabolic characteristics of ruminants, the nutritional effect is mainly as a nitrogen source for the synthesis of protein by tumor stomach microorganisms, thus playing a nutritional role in supplementing protein and saving protein feed.
(1) Urea.   
Urea is cheap, contains up to 46% nitrogen, and is equivalent to 2.8 kg of crude protein per kg of urea, or 7 kg of crude protein content of soy cake. Experiments show that replacing protein feed in cattle and sheep with the right amount of urea can not only reduce costs, but also improve productivity.
Urea is mainly used in adult ruminants and is not suitable for feeding yaks and lambs that have not yet fully developed tumor stomachs. When adding urea, it is necessary to note: supply a sufficient amount of soluble carbohydrates to provide energy for the stomach microorganisms, the daily grain contains a certain amount of protein, tests show that when the crude protein content of the same day is 11% to 12%, the urea utilization effect is best, the supply of the right amount of and balanced minerals, including calcium, magnesium and trace elements cobalt, zinc, etc., to ensure the supply of moderate vitamins, especially vitamin A, D.