SUMMARY

Using live microorganisms originally call probiotics is allowed from FDA (Food and Drug Administration, USA), characterized as live, capable for life, microorganisms which are normaly appearing in nature. In contemporary terminology are designated and as directly feeding microorganisms or DFM. On the market in the world are present larger number of commercial products for feeding dairy cows. Some of these products contain live bacteries, until significantly larger number on the basis yeasts, as is Yeasture. Others contains extracts of bacteries or products of their fermentation. Commercial products which contain live microorganisms must to provide number of cells which are designated on garancy. All today known commercial products are from microorganismes which are generally designated as harmless.