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.
Commonly used and potential plant protein sources for cattle
Source | Scientific name | Area grown | Yield/ha | Potential yield |
Soybean meal | Glycine max | 18 433 | 800 | 2500 |
Sunflower meal | Helianthus annuus | 15 460 | 500 | 3 000 |
Beans | Phaseolus vulgaris | 106 627 | 700 | 2 500 |
Ground nuts | Arachis hypogaea | 95 399 | 750 | 2 400 |
Pigeon peas | Cajanus cajan | 87 758 | 800 | 2 500 |
Cowpeas | Vignia unguiculata | 48 157 | 600 | 2 000 |
Chick peas | Cicer arietinum | 1 070 | 700 | 2 000 |
Bambara or groundbeans | Vigna subterranea | 3 128 | 800 | 3 000 |
Sesame | Sesamum indicum | 97 | 500 | 1 000 |
Green grams | Vigna aureus | 1 216 | 700 | 2 000 |
Plant proteins
The bulk of the protein of ruminants comes from plant sources. The protein content of plant varies considerably from one type to another. Even within the same plant, there is considerable variation from one stage of maturity to another or from one part of the plant to another. Proteins in plants are primarily associated with the tissues which are actively metabolizing such as leaves, centers of growth and the seeds. Eventhough they are not
especially high in protein by comparison with other feedstuffs, the vegetative portions of many plants supply an extremely large portion of the protein in the total ration of livestock, simply because these portion of feeds are consumed in large quantities. Needed protein not provided in these feeds is commonly obtained from one or more of the oilseed by-products
–soybean meal, cottonseed meal, groundnut meal, safflower meal, sunflower meal, rapeseed meal linseed meal, sesamum meal and coconut meal. The protein content and feeding value of these products vary according to the seed from which they are produced, the amount of hull and/or seed coat included and the method of oil extraction used. Sometimes the unprocessed seed is used to provide both a source of protein and a concentrated source of energy. The oil bearing seeds are especially high in energy because of the oil they contain.
Additional plant proteins are obtained as by-products from grain milling, brewing and distilling and starch production. Most of these industries use the starch from grains and seeds, then dispose of the residue which contains a large portion of the protein of the original plant seed.
