Description: The yeast cell wall is recovered as a by-product during the production of soluble extracts from brewer's yeast. The yeast cell wall is made up predominantly of glucan, mannan and chitin polymers. These three components account for more than 80% of the dry matter of cell wall faction. The ß-glucan, which is a homopolimer of glucose linked through ß(1-3), ß(1-4) or ß(1-6)-D glycosidic bonds, is the predominant polysaccharide present in the yeast cell wall. It often amounts to 12-14% of the yeast cell dry matter. An proximate Analysis of cell wall contains less than 20% noncarbohydrate material that includes protein, nucleic acid, lipids, and ash (REED and NAGODAWITHANA, 1991).

Production Process: The source of yeast is selected breweries located less than 70 kilometres far from producing unit. The brewer's yeast is collected in liquid state, washed many times as to debitter, and then autholyzed. Autholysis is achieved submitting yeast to high temperatures at a controlled pH level. After yeast autholysis is completed, cell wall and yeast extract is separate by centrifugation, and cell wall is spray dried. No additives are added, from chemical or natural sources. Feed producers can expect 'a product that is 100% pure cell wall material.

Application: The therapeutic effect of glucan has been primarily due to stimulation of the reticulo endothelial system (RES), which in turn produces increased amounts of macrophages that playa key role in the body's natural immune system. The precise function of the macrophages is to absorb and destroy the invading particles through phagocytosis. Recent studies have demonstrated the beneficial effect of glucan in improving host resistance by enhancing both humoral and cellular immunity to certain malignant tumors as well as to certain bacterial and viral infections (DiLUZIO, 1985; REED and NAGODAWITHANA, 1991). However, the cell wall has the following properties:

Immune stimulation: Saccharomyces cerevisiae cell wall consistently contains high concentrations of ß-1,3-D-glucan available. It is very important to the animals because produce a significant increase in non-specific protection from bacterial, fungal, viral (those identifiable by the respective immune systems) diseases, as well as protection from stresses related to shipping handling and harzadous conditions.

Disease control: Glucans are one of the most important structural elements of cell walls (ROSENBERGER, 1976), and are known to stimulate defence mechanisms in a range of higher organisms. The studies have demonstrated the therapeutic value of phosphorylated glucans in combating a variety of diseases caused by bacteria, fungi, viruses, and also in attempting to change the course of certain neoplastic conditons (RAA et al., 1992). Saccharomyces cerevisiae cell wall is also an important source of MOS, "Mannan oligosacaccharides", that acts in the gut of animals capturing hostile gut-wall-attacking bacteria like E. Coli (MOS locks into hostile bacteria molecular structure and carries them safely outside).

Profit enhances: Saccharomyces cerevisiae cell wall can be applied in all sorts of feeds, but it is especially recommended for weaning piglets and acquaculture feeds.