Xixi Li, a PhD candidate, from the University of Western Australia (UWA), takes a tar bush on the subject of reducing controversial agricultural green house gas emissions.
Two thirds of Australia’s agricultural emissions come from enteric methane, which is produced during rumen fermentation in ruminants, such as sheep. It was necessary to investigate how to lower the levels of emissions produced from feed manipulation.
Li has based her PhD research on how the Australian native plant, Eremophila glabra, or tar bush, when consumed by sheep, helps reduce methane production in the rumen. Li has been one of two recipients of the 2011 Mike Carroll Travelling Fellowship.
Xixi Li had also attended the 8th International Symposium on the Nutrition of Herbivores in Wales, UK, which she presented her paper and discussed her UWA Institute of Agriculture (IOA) research, with leading scientists, in the field of livestock population.
“Xixi has already demonstrated that tar bush has dose related, persistent, modulating effects on rumen microbes and she will use this exciting finding to design an experiment where she will feed tar bush to sheep in respiration chambers to accurately measure methane emissions and also to ensure the effects she’s observed in the laboratory are replicated in the animal itself,” says Professor Phil Vercoe, Li’s PhD Supervisor and UWA IOA Animal Production Systems Program Leader.
According to Vercoe, Li’s ultimate aim is to develop a more diverse forage bases for grazing ruminants in Australia, including plants such as E. glabra.
It was after screening more than 100 native plants, to find ways in improving the feed supplements feed intake, digestibility and rumen fermentation, Li and her colleagues had selected the E. glabra, a shrub that tolerated harsh growing conditions and could provide livestock fodder even in drought conditions.
“I have found an optimal inclusion level of E. glabra, which can reduce methane production by about one third, while not adversely affecting general rumen fermentation,” says Li.
“It seems that with no effect on total volatile fatty acid concentrations, the major end products of rumen microbial fermentation, E. glabra alters the diversity and activity of ruminal microbes.”
Li believes that if methane production could be reduced, while increasing total volatile fatty acid production, animal production could be improved. However, in order to provide its effects, the E. glabra only needs to make up as part of the animal’s diet in which the tar bush would be only a component of a more diverse mixture of plants for grazing.
“This would give us a solid base to reduce greenhouse gas emissions from ruminants and contribute to developing green, sustainable and profitable grazing systems for WA sheep,” says Li.