ARS | Publication request: THE SURVIVAL OF SILAGE INOCULANT LACTIC ACID BACTERIA IN RUMEN FLUID

Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 21, 2003
Publication Date: June 1, 2003
Citation: WEINBERG, Z.G., MUCK, R.E., WEIMER, P.J. THE SURVIVAL OF SILAGE INOCULANT LACTIC ACID BACTERIA IN RUMEN FLUID. JOURNAL OF APPLIED MICROBIOLOGY. 2003. v. 94. pp. 1066-1071.

Interpretive Summary: One of the most common additives used to make silage for cattle is the bacterial inoculant. Inoculants contain lactic acid bacteria that supplement the natural bacteria found on the crop, and they ensure a fast and efficient fermentation of the crop in the silo. These inoculants can also increase the milk production and weight gain of cattle fed silage. However, we do not understand how these products improve animal performance. Our first step to investigate this phenomenon was to determine if bacteria from inoculants could live in the main stomach (rumen) of the cow. The rumen is where many types of bacteria help the cow digest her food. We placed 12 different inoculants in fluid taken from the rumen of several cows and then determined if the inoculant bacteria survived. All did survive, but some did better than others. They also helped keep the rumen fluid from getting too acidic, which may be a key to explaining how they help the animal to perform better. More experiments are needed to completely understand how inoculants benefit cattle. Once we understand how inoculants work, we will be able to select even better bacteria for future products that will help cattle to use their feed more efficiently, producing more milk and meat and less manure.

Technical Abstract: Twelve commercial silage inoculants were added at 1 and 10 million CFU/ml to clarified and strained rumen fluid taken from dairy cows, respectively, with and without 5 g/l glucose. The vials of inoculated rumen fluid was incubated anaerobically at 39 C. Changes in pH, lactic acid bacterial numbers and fermentation products were monitored for 72 h. In both clarified and strained rumen fluid, supplementation with glucose decreased pH and increased numbers of lactic acid bacteria relative to those in vials without glucose. The inoculants varied with regard to their effect on pH change and growth. In strained rumen fluid 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 that is helpful for fiber digestion.