Rumen degradability and gas production as influenced by different strains of Bacillus thuringiensis

The effect of six Bacillus thuringiensis (Bt) strains on diet degradability was evaluated using an in vitro gas production technique. Spores (5.7 × 106 spores) of different Bt strains (907, 1192, 2036, 2493, 2496, and S1185) plus a control (no spores) were used as treatments with four replicates (inocula) in duplicate. Fermentation processes were evaluated and ruminal microorganisms were quantified. Compared with the control, the Bt907 strain decreased dry matter (DM) and organic matter (OM) degradability without affecting the Fibrobacter succinogenes population, whereas the other strains reduced this population without altering DM and OM degradability.