The importance of cellulolytic and xylanolytic activities of Bacillus subtilis on dairy cow feed digestibility

Abstract

A large body of literature has accumulated on the beneficial impact of the administration of Bacilli to dairy cows, particularly on dry matter intake, lactation performances and milk composition. In this work we sought to establish whether the ability of B. subtilis to secrete cellulase and xylanase enzymes could be involved in the positive effect exerted by these bacteria. Several feed ingredients were treated with two B. subtilis strains only differing for the amount of secreted cellulosolytic and xylanolytic enzymes, and feed quality was assessed. We found that in vitro fibre digestibility correlated with the activity of those enzymes. Our results revealed that B. subtilis cellulases and xylanases can effectively improve forage quality, providing a scientific rationale on the use of Bacilli as forage supplements to improve animal productivity. Moreover, a particular care was taken in designing a sustainable and economically viable Bacillus-based additive preparation process.