Protein sources

Ingredients that contain more than 18% of their total weight in crude protein are generally classified as protein feeds. Protein is one of the critical nutrients particularly for the young rapidly growing animal and high producing adults, although, it may be secondary to energy or other nutrients at times. In addition, protein supplements are usually more expensive than energy feeds, so optimal use is a must for any practical feeding system. Protein supplements may be further categorized according to source of origin as i) plant protein ii) animal protein iii) non protein nitrogen and iv) single cell protein.

Plants provide more than 90% of the protein feeds used in livestock rations. Most protein feeds of plant origin consist of processed oilseeds. Millings by-products generally make up the remainder of the plant protein feeds. Many protein feeds of animal origin are derived from sources that are considered unsuitable for human consumption. Many proteins of mammalian origin are banned for use in feeding of cattle because of the threat of mad cow disease.