This study aimed to determine the ideal ratio of β Glucan in feed additives as immune stimulants and anti-mycotoxigenic agents when used as a feed additive in mice in premix, as a step to reach a final composite of feed additive as a premix with an ideal ratio of β Glucan. Two different bio-assays were employed in the experiment; the Immune Globulin (IGs) test in blood and the molecular Cyto-genetic parameters (micro-nucleus test and chromosomal aberration). In order to achieve such a purpose we use 7 different groups of mice with different concentrations of β-glucan in feed premix, to compare the results 2 groups of mice were experimented with as a negative and positive control, the feed used was prepared as a typical composition of feed for the age stage of mice without any other additives to experiment the individual effect of β-Glucan only, the doses of β-glucan have been chosen as the minimum and maximum ratio of β-glucan in commercial premixes.