This European Standard defines general rules for the enumeration of probiotic bacilli in feeds containing bacilli (Bacillus species) as a single microorganism, component or mixed with other microorganisms. This method is not applicable to mineral feeds which are defined as complementary feeding stuffs composed mainly of minerals and containing at least 40% crude ash (Council Directive 79/373/EEC) [3]. There are different categories of feed samples: a) Additives containing about 1010 colony forming units (CFU)/g; b) Premixtures containing about 108 CFU/g; c) Feeds, meal or pellets, which contain about 106 CFU/g and include complete feeding stuffs, and milk replacers. The detection limits are 500 (5 x 102) colony forming units per gram (CFU/g). The limits of determination are 2 x 104 CFU/g.