Feeds that contain an insufficient amount of protein, indispensible amino acids and vitamins are inefficient and unbeneficial. Their expenditure for obtaining this or that animal breeding products is increased in several times. In conditions of intense farm keeping, it is important not only to provide the sufficient gross production of feeds but also receive feeds with the high content of protein, which are balanced as for the amino acid content.

Protein and amino acid exchange of ruminants and non-ruminants is different.  The latter have a single-chambered stomach, and the microflora of their gastrointestinal tract exerts its activity in the bowel. There are no significant synthetic processes in the non-ruminants’ stomach. Influenced by the gastric juice, feed proteins are transformed here into amino acids, and the transamination reaction proceeds. However, such indispensible amino acids as lysine, threonine, arginine are not synthesized as a result of transamination at all or they are synthesized in such a minor amount that does not have practical significance. Therefore, regarding the ruminants, such amino acids should be presented in the feeding ration within the required amounts.

Ruminants are less demanding as for the full value of feed proteins, as their fore stomach is inhabited by rich microflora that synthesize all amino acids, including indispensible ones, even from elementary nitrogen-containing substances. Initially, microorganisms synthesize protein in their cells, after death, where amino acids are released and serve for the benefit of the host animal.

Such feature of ruminants enables to use the nitrogen-containing elementary substances (urea and ammonium salts) for partial redemption of the protein deficit. Microorganisms in the paunch of ruminants synthesize glutamine, glutamine acid, glycine and valine in great amounts. They are transported into liver, where other amino acids are synthesized.

In existing feeding rations there in not by far always enough protein, necessary amino acids and vitamins. Therefore, the issue of their further introduction into the feeds in the form of specific preparations, in particular, such obtained by use of microorganisms,  is relevant.  That is, the issue of obtaining feed protein by means of microbe synthesis captured significant attention from the scientists. Owing the quick breeding, the microorganisms are characterized by incomparably greater productivity  than the higher organisms. For instance, a relatively minor yeast plant produces nearly 30t per day of the mass containing 15t of protein, which is 5.5 thousand tons per year. In order to obtain such products from cattle , one should have a herd of several thousand of heads.

Production of feeding yeasts on the waste from the distillery, sugar industry and the cellulose hydrolyzates has been implemented. Ammonium salts are used by yeasts as a source of nitrogen.  The large-scale derivation of feeding protein has been arranged. The ready products are the mass that has only 7-10% of moisture, i.e. protein-vitamin concentrate (PVC).

The PVC research showed that it is equal to the animal-origin feeding products. PVC has all indispensible amino acids within the same amounts as traditional feeding additives. It is only prevailed by the fish meal as for the content of methionine. PVC is rich of vitamins and prevails fish meal and soy meal as for a range of indicators. Experiments showed PVC’s full safety and biologic value for animals. In particular, this preparation may substitute milk at feeding calves.

It should be noted that as for certain chemical  indicators, yeast protein has some advantages compared to the bacterial one.

The Institute of Microbiology and Virology recommends adding Candida feeding yeasts as a protein additive, which are grown on the cooked grain chop, meal and other substrates. Before using, the yeast mass is heated for the purposes of destruction of yeast cells, which increases their digestibility. Feeding yeasts should be prepared rather at places of their consumption than plants.

Lots of microorganisms may be used to obtain indispensible feeding amino acids and vitamins. Only correct combination of all components of a feed provides the best result, while the lack of at least one component reduces the efficiency of others. In some cases, it is available to simplify the set of ingredients included in a compound feed and reduce their cost. For instance, enriching the feeds with vitamin B12 substitutes the deficient and costly animal protein with the plant one. At that, the animals’ productivity is not reduced.

Prior to the Second World Warm, there was scarcely any production in every country. By now, the reasonability of using the amino acids has been proven in animal breeding, where they have large economic effect. There is no need to obtain pure preparations  for feeding animals, it suffice only to have concentrates that are cheaper and simpler in terms of production.

Microorganisms have a great feature – ability to accumulate a vast number of some valuable amino acids within the medium. The extent of such “oversynthesis” may be very significant. That is, some organisms produce up to 200 g of aspartic acid, 100 of glutamine acid, 16 g of valine per liter of the medium. There are microorganisms that synthesize a large amount of L-lysine, L-valine, L-methionine and tryptophane.