Bacteriophages in the rumen: types present, population size and implications for the efficiency of feed utilisation

Abstract

One cause of a reduction in the efficiency of feed utilisation in the rumen is the non-specific lysis of bacteria within the rumen and subsequent fermentation of the bacterial protoplasm. Bacteriophages are implicated in this lysis, are obligate pathogens of bacteria and occur in dense populations in the rumen.
Large numbers are present (up to lo*’ per millilitre of fluid) in the rumen. These viruses are morphologically diverse with 26 distinct types from three viral families (Myoviridae, Siphoviridae and Podoviridae) being represented. The use of the DNA-based methodology, Pulsed Field Gel Electrophoresis, has allowed an estimate of phage numbers in the rumen at a point in time. This procedure will enable investigations of changes in the phage population in relation to changing dietary regimes. Preliminary evidence suggests that diet may influence viral activity and therefore dietary manipulation could, in the future, be used to reduce viral activity and improve the flow of microbial protein to the intestines.