Survival of silage lactic acid bacteria in the goat gastrointestinal tract as determined by denaturing gradient gel electrophoresis.

AIMS

To determine the survival rate of silage lactic acid bacteria (LAB) in the ruminant gastrointestinal tract.

METHODS AND RESULTS

Wilted Italian ryegrass (Lolium multiflorum Lam.) silage (containing 1·9×10(6) CFU LAB g(-1)) was fed ad libitum to three goats equipped with rumen cannulae. Silage was given alone or with concentrates at a 1:1 ratio on a dry matter basis. Rumen fluid was then obtained 2, 4 and 8h after the morning feeding. Denaturing gradient gel electrophoresis was performed to compare LAB communities in silage, rumen fluid and faeces. The LAB detected in the wilted silage included Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus murinus and Lactobacillus sakei. Bands indicative of Lact. murinus were detected in either the rumen fluid or faeces, whereas the bands indicative of Lact. plantarum, Lact. brevis and Lact. sakei were not. Although the rumen fluid LAB counts and volatile fatty acid concentrations were higher in goats fed silage plus concentrates compared with those fed silage alone, the LAB communities themselves remained unaffected. Sampling times and goat-to-goat variations did not affect the LAB communities found in the rumen fluid.

CONCLUSION

LAB communities found in the gut are not remarkably affected by the consumption of silage LAB, even when the silage is accompanied by concentrates that facilitate gut fermentation.

SIGNIFICANCE AND IMPACT OF THE STUDY

Although silage can improve probiotic function, it may be difficult for silage LAB to survive the digestive process in the ruminant gastrointestinal tract.