Three species of Australian native plants, Pimelea trichostachya, P. simplex and P. elongata, are endemic to the arid rangelands of Queensland, New South Wales and South Australia and are responsible for Pimelea poisoning, also known as St George or Marree disease. Pimelea poisoning occurs in cattle ingesting Pimelea plants, with the orthoester simplexin identified as the responsible toxin. There is no effective treatment and economic losses have been estimated at over $50 million during significant Pimelea poisoning events. In a previous feeding trial, animals were fed increasing amounts of Pimelea, and after initially showing signs of poisoning, the animals appeared to adapt to ingesting Pimelea, possibly through rumen microbial degradation of the toxin (Fletcher et al., 2014). Kangaroos, forestomach fermenters, often graze pastures containing Pimelea with no apparent ill effects.
To investigate the degradation effect further, a series of 30 day in vitro, anaerobic fermentations were undertaken
