Evidence of Endotoxins in the Rumen Bacteria of Cattle Fed Hay or Grain

Abstract

The rumen bacterial fraction obtained from rumen fluids of cattle fed hay or grain was subjected to phenol-water or aqueous ether extraction procedures. The purified and lyophilized extract was endotoxic based on the following characteristics: 1. Proved lethal to mice and chick embryos. Toxicity in mice was potentiated by actinomycin D. 2. Enhanced susceptibility to streptococcal infection in mice. 3. Induced biphasic fever and leukocyte response in rabbits. 4. Elicited local Schwartzman reaction in rabbits. 5. Caused (in nanogram quantities) gelation of limulus lysate. A parallel study with commercial endotoxins of Escherichia coli or Salmonella typhosa showed that endotoxins from them were several times more endotoxic than those from rumen bacteria. This may be due to the presence of contaminating bacterial polysaccharides or to an inherently low endotoxicity of rumen bacteria.