The animal protein industry has exponentially grown, and intensive production practices cause unavoidable stress to the animals as a result of confinement, transport and handling. Stress generates a physiological condition characterized by suppressed immunity, and consequently, higher disease susceptibility. Yeast Beta Glucan in Aquaculture In aquaculture, in particular, fish are not easily observed by the stock person, and disease outbreaks are often overlooked. Therefore, novel ways to boost the immune response of fish are needed. One natural option that is highly effective is the use of beta glucan because they are considered modifiers of biological response due to their immunomodulatory

Introduction Yeast beta-glucan and Yeast Cell Wall (YCW) are two additives from yeast that could provide Polysaccharides in Feed. They are yeast derivatives to improve animal performance, and there are different confusing concepts between them. In this article, beta-glucans and YCW will be put together to discuss their relation, function, and usage in the field of animal nutrition. Brief on Yeast Cell Wall YCW is often called the MOS product; it is the natural source of mannan-oligosaccharides (MOS) and Yeast 1,3/1,6-D-beta glucan. YCW contains 20%-35% Mannan, 20%-35% Glucan, 2%, and less than 35% protein. In the feed industry, Yeast cell