Ultrasonic vocalizations as indicators of welfare for laboratory rats (Rattus norvegicus)

Burman, Oliver and Ilyat, Alex and Jones, Gareth and Mendl, Michael (2007) Ultrasonic vocalizations as indicators of welfare for laboratory rats (Rattus norvegicus). Applied Animal Behaviour Science, 104 (1-2). pp. 116-129. ISSN 0168-1591

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Ultrasonic vocalizations as indicators of welfare for laboratory rats (Rattus norvegicus)
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Official URL: http://dx.doi.org/10.1016/j.applanim.2006.04.028

Abstract

Adult laboratory rats produce two distinct types of ultrasonic vocalization (USV) that appear to reflect the caller’s emotional state, either positive (50 kHz) or negative (22 kHz). If these calls can influence the emotional state and related behaviour of group-mates, then such calls may act as useful indicators of welfare for not only the vocalizing rat, but also other non-vocalizing individuals within auditory range.We therefore investigated the effect of playing back these different USVs on the behaviour of rats in an emergence test, a test of anxiety. In an initial experiment, we compared the response of 20 rats to playback of either background noise or to playbacks of 22 kHz vocalizations from conspecifics. Rats that received playback of the 22 kHz USVs were less likely to emerge, showed an increased latency to emerge and spent less total time in the open arena than rats receiving playback of background noise, suggesting a state of increased anxiety. In a second experiment, the same 20 rats received playback of either background noise or 50 kHz
vocalizations from conspecifics. Rats receiving 50 kHz USV playback showed no difference in emergence behaviour to those rats receiving background noise. Taken together, these results suggest that 22 kHz USVs can induce a negative emotional state of increased anxiety in rats hearing the vocalization, and could therefore be a useful indicator of welfare for rat groups; including both callers and non-calling group-mates.

Item Type:Article
Additional Information:Adult laboratory rats produce two distinct types of ultrasonic vocalization (USV) that appear to reflect the caller’s emotional state, either positive (50 kHz) or negative (22 kHz). If these calls can influence the emotional state and related behaviour of group-mates, then such calls may act as useful indicators of welfare for not only the vocalizing rat, but also other non-vocalizing individuals within auditory range.We therefore investigated the effect of playing back these different USVs on the behaviour of rats in an emergence test, a test of anxiety. In an initial experiment, we compared the response of 20 rats to playback of either background noise or to playbacks of 22 kHz vocalizations from conspecifics. Rats that received playback of the 22 kHz USVs were less likely to emerge, showed an increased latency to emerge and spent less total time in the open arena than rats receiving playback of background noise, suggesting a state of increased anxiety. In a second experiment, the same 20 rats received playback of either background noise or 50 kHz vocalizations from conspecifics. Rats receiving 50 kHz USV playback showed no difference in emergence behaviour to those rats receiving background noise. Taken together, these results suggest that 22 kHz USVs can induce a negative emotional state of increased anxiety in rats hearing the vocalization, and could therefore be a useful indicator of welfare for rat groups; including both callers and non-calling group-mates.
Keywords:Animal Welfare, Animal Behaviour, Ultrasonic Vocalizations, Laboratory rats
Subjects:C Biological Sciences > C120 Behavioural Biology
D Veterinary Sciences, Agriculture and related subjects > D328 Animal Welfare
Divisions:College of Science > School of Life Sciences
ID Code:3836
Deposited By: Oliver Burman
Deposited On:13 Jan 2011 19:53
Last Modified:13 Mar 2013 08:53

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