Arena studies offer a more realistic worst case scenario test system than conventional housing for Wood mouse ecotoxicological studies Nicola Dennis, Sarah Milner, Ken Tarrant Fera Science Ltd Pre registration testing • • • • Avoidance testing Behavioural studies Consumption studies Dehusking • Aim to replicate worst case scenario of hunger and no choice • No defined test system • • • • Wood mouse (Apodemus sylvaticus) Food deprivation Singly housed Plastic cages Why? • Convenient • Always do it this way • It works Arena as the test system • Allows for the expression of more natural behaviour • Group housing • Easier to film if requiring behavioural data Experimental design • Aim to obtain information on feeding rates • • • • • • Same sex sibling pairs of mice 14 days pre acclimatisation 2 days monitoring consumption 4 hours food deprivation Day -1 Presentation of reference item Day 0 Presentation of test item Food deprivation Hours Yes 4 Test a.i Consumption Mortality System conc % % Arena 2.5% 39.9 0 Optimizing the test system •Encountered mortalities •Unexpected •Why? Food deprivation Test a.i Consumption Mortality Hours System conc % % Yes 4 Arena 2.5% 39.9 0 Yes 4 Arena 2.5% 32 50 • What was the arena offering that was different? • Larger area for the mice • Allowing for more movement • Mice becoming ‘fitter’ • Was this affecting their ability to withstand additional challenges? Weight change during the course of the study period 30.0 Weight (g) 28.0 26.0 Males Females 24.0 22.0 20.0 18.0 DAY -17 DAY -3 DAY -1 Food deprivation Test a.i Consumption Mortality Hours System conc % % Yes 4 Arena 2.5% 39.9 0 Yes 4 Arena 2.5% 32 50 Yes 4 Arena 3.0% 58.1 37.5 Conclusion • The type of housing may affect the out come of the trial • The larger the cage the ‘fitter’ the animal • Energy demands more characteristic of wild populations However • • • • More representative worst case scenario Express more ‘wild type’ behaviour Stepping stone between lab and field studies Additional information can be obtained