Early environmental enrichment protects captive-born striped mice against the later development of stereotypic behaviour

Abstract

a b s t r a c tUnderstanding how birth origin (whether born in the wild or captivity) influences behavioural development is important for fundamental and applied ethology, especially when captive-bred (CB) individuals from wild species are used in research or conservation. CB animals are typically much more prone to stereotypic behaviour (SB) than are wild caught (WC) conspecifics, an effect which in striped mice is accompanied by increased tendencies to form behavioural routines. However, WC mice, if stereotypic, are far more severely affected than CB mice and are also more physiologically stressed and inactive than CB mice, regardless of their stereotypy status. Capturing subjects from the wild to further study these latter effects raises serious practical, ethical and potentially conservation concerns. Here, we therefore tested whether rearing CB striped mice in enriched conditions and then placing them in standard cages could provide a more suitable model for investigating how wild-caught (WC) conspecifics respond to the reduced environmental complexity they experience after capture. Compared with striped mice which were always standard-housed (n = 36), enriched striped mice (n = 24) were four times less likely to develop SB and, similarly to the benefits of being wild born, early environmental enrichment (30-170 days) successfully protected CB striped mice from the emergence of SB after transfer to standard caging (171-240 days). However, unlike WC mice, previously enriched CB striped mice which then became stereotypic did not develop markedly more severe SBs; they showed diverse forms, unlike stereotypic WC mice which exclusively circuit ran; and they were not more inactive once SB levels were controlled for. These findings thus show that early environmental complexity can have lasting suppressive effects on SB, suggesting that early enrichment protocols could indeed provide a practicable, potentially more ethical model for investigating the causal mechanisms underpinning birth origin effects on SB. Furthermore, they add to a corpus of data for this species showing that more naturalistic early experiences, both social and physical, lastingly protect against SB development. These results also highlight how unpredictable and poorly understood early enrichment effects are (since in some species early enrichment exacerbates later SB); and moreover reveal that early environmental complexity is not the sole factor shaping behavioural phenotypes in WC animals, with differential social experience and human contact being other likely causes of developmental divergence.

Naturalising diet to reduce stereotypic behaviours in slow lorises rescued from wildlife trade

“…Abnormal behaviours such as stereotypies and abnormal aggression can be influenced by unsuitable living conditions, poor diet and human handling in captivity (Novak et al, 2006). In this study, the number of stereotypic behaviours significantly decreased with environmental enrichment as found in other mammals (e.g., Mus musculus, Jones et al, 2011;Phoca vitulina richardii, Chudeau et al, 2019). As one would expect, supplying a natural diet produced a positive welfare outcome (Hosey, 2013).…”

Evaluation of different types of enrichment - their usage and effect on home cage behavior in female mice

“…It has been shown that stereotypical behavior is associated with impoverished keeping conditions in many species including mice [ 47 , 48 ]. In addition it has been shown in various studies that stereotypies can be reduced and prevented by enrichment [ 11 , 12 , 49 , 50 ]. The results of our study confirm and extend these findings and thereby underline the need for a varied environment for laboratory mice.…”

Behavioural Differences in Brown-Norway and Wild-Type Rats Maintained in Standard or Enriched Environment in Response to Novelty in a Familiarised Environment

“…By contrast, in Brown Norway rats the effect of the environment was not extinguished in later sessions. Jones, Mason, & Pillay (2011) and Latham & Mason (2010) demonstrated the role of the factor called environmental downshift. This procedure involves moving animals housed in enriched environmental conditions to standard laboratory cages for a period immediately preceding measurements.…”

“…Seven days before tests, rats kept in enriched conditions were moved to standard cages to ensure standardisation of the appropriate measurement procedure. The research by Jones, Mason, & Pillay (2011) and Latham & Mason (2010) quoted above were rooted in the theoretical framework of animal welfare. Nevertheless, the effects identified in those experiments are relevant for basic research.…”

“…Environmental enrichment was found to counteract cognitive impairments caused by, among other things, brain damage and stress (Moncek, Duncko, Johansson, & Jezova, 2004;Sackett, Novak, & Kroeker, 1999). Another important issue investigated within the environmental enrichment framework is the animal welfare (Jones, Mason, & Pillay, 2011;Reinhardt, 2003). Providing animals with environmental stimulation by enriching their physical surroundings has beneficial effects on their functioning in captivity (Swaisgood, White, Zhou, Zhang, & Lindburg, 2005).…”