<p>During 2017/18, a sheep vaccination trial, including measurement of methane emissions, was conducted and all vaccinated animals produced antibodies against each of the 19 protein/protein fusions present in the mix of recombinant proteins. This is an important finding as anti-methanogen vaccines are very likely to contain multiple antigens. The issues that arose with assay repeatability in the vaccine programme in 2016/17 have been addressed over the past year. The methanogen growth assay has been refined in order to ensure reliable testing of antibodies against candidate vaccine targets. New auxiliary assays (ELISA, Western blotting, flow cytometry) for measuring &lsquo;effectiveness&rsquo; of antibodies produced against specific targets have been developed.</p>