The survival of silage inoculant lactic acid bacteria in rumen fluid

Aims: To determine whether lactic acid bacteria (LAB) used in inoculants for silage can survive in rumen fluid (RF), and to identify those that survive best. Methods and Results: Twelve commercial silage inoculants were added at 107 CFU ml−1 to strained RF (SRF) taken from dairy cows, with and without 5 g l−1 glucose and incubated in vitro at 39°C. Changes in pH, LAB numbers and fermentation products were monitored for 72 h. In the inoculated RF with glucose, the pH decreased and numbers of LAB increased. The inoculants varied with regard to their effect on pH change and growth. In the SRF, both with and without glucose, the pH values of the inoculated samples were generally higher than those of the uninoculated controls throughout most of the incubation period. This may suggest a positive effect on the rumen environment. Conclusions: LAB used in silage inoculants can survive in RF in vitro. Significance and Impact of the Study: This is the first step in studying the probiotic potential of silage LAB inoculants for dairy cattle. The survival of these LAB in RF may enable them to interact with rumen microorganisms and to affect rumen functionality.