Arena studies offer a more realistic worst case scenario test system

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
•
•
•
•
•
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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