Submitted to: Applied Biochemistry and Biotechnology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/2/2003
Publication Date: 6/1/2004
Citation: Weinberg, Z.G., Muck, R.E., Weimer, P.J., Chen, Y., Gamburg, M. 2004. Lactic acid bacteria used in inoculants for silage as probiotics for ruminants. Applied Biochemistry and Biotechnology. 118:1-10. Interpretive Summary: The most common additives used to make silage for cattle are bacterial inoculants. 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 10 different inoculants in fluid taken from the rumen of several cows and then determined if the inoculant bacteria survived. All survived, 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: Many studies have shown the beneficial effects on ruminant performance of feeding them with silages inoculated with lactic acid bacteria (LAB). These benefits might derive from probiotic effects. The purpose of the current study was to determine whether LAB included in inoculants for silage can survive in rumen fluid (RF), as the first step in studying their probiotic effects. Experiments were conducted in the United States and Israel with clarified (RF) and strained RF (SRF) that were inoculated at 106'108 microorganisms/mL with and without glucose at 5 g/L. RF with no inoculants served as control. Ten commercial inoculants were used. The RF was incubated at 39°C and sampled in duplicates at 6, 12, 24, 48, 72, and 96 h for pH and LAB counts. The results indicate that with glucose the pH of the RF decreased during the incubation period. In the SRF, the pH of the inoculated samples was higher than that of the controls in most cases. This might be a clue to the mechanism by which LAB elicit the enhancement in animal performance. LAB counts revealed that the inoculants survived in the RF during the incubation period. The addition of glucose resulted in higher LAB counts.