Browsing by Person "Muetzel, Stefan"

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    Influence of tropical supplemental feeds on the composition and activity of rumen microorganisms, quantified by oligonucleotide probes
    (2001) Muetzel, Stefan; Becker, Klaus
    This study was undertaken to evaluate the applicability of oligonucleotide probes to unravel the population structure of the rumen flora in vitro. At first a RNA extraction and cell lysis method for rumen fluid samples was optimised. However when tannin containing plants were present in the samples the method failed to recover microbial RNA. The comparison of two rumen fluid sampling sites for inoculation revealed a higher in vitro gas production from samples inoculated with rumen fluid from the feed mat compared to the liquid phase. The higher gas production was not explained by a higher digestibility of the substrates. Changes in the population structure, population density and the kinetic of the fermentation might be responsible for the observed differences. This experiment showed that for interpretation of the results, population structure data have to complemented with metabolic parameters. In a supplementation experiment it was demonstrated that amount, but also the efficiency of the microbial biomass production was positively affected. Comparison of the population structure of the cell wall degrading consortium and cellulase activity revealed that Fibrobacter was mainly responsible for the expression of this enzymatic activity. Such a comparison is a new strategy which will lead to a better understanding of the complex fermentation processes in the rumen. The analysis of the population structure of the cell wall degrading organisms showed a competition for substrate or attachment sites between Fibrobacter and Ruminococcus albus which was independent of the substrate incubated, the time of sampling and the origin of the inoculum.