Urea

Protein is needed for tissue maintenance, growth and milk production. Through the action of microbes in the rumen, cattle can use inorganic sources of nitrogen (such as urea) to manufacture protein. Urea is a relatively cheap source of protein - but is ineffective without a source of fast release energy (such as molasses or grains). Under drought conditions, without the provision of energy, urea cannot be used efficiently and may cause fertility problems or other toxicity. Similarly, inadequate sulphur will prevent urea being effective - Rumevite supplements with urea will also include supplementary sulphur.

Some natural protein (sometimes called bypass protein) passes through the rumen without being broken down by bacteria. It will be digested and absorbed in the small intestine. The quantity of natural protein varies greatly between pastures and declines as the pasture matures. Lupins and other seeds generally have higher levels than grains. Vegetable protein meals such as copra meal or cottonseed meal, are particularly
good sources. The relatively high costs of vegetable protein sources mean that feeds high in natural protein will cost more than urea-based supplements. When first weaned, animals do not have a fully functional rumen. They are less able to utilise urea, and when pasture protein is inadequate (mid-late dry season) should be supplemented with a natural protein source.