Impact of tank background on the welfare of the African clawed frog, Xenopus laevis (Daudin) (2016)

Holmes, A. M., Emmans, C. J., Jones, N. et al.

Abstract

The captive environment of a laboratory animal can profoundly influence its welfare and the scientific validity of research produced. The African clawed frog (Xenopus laevis) is a common model organism, however current husbandry guidelines lack supporting quantitative evidence. The visual environment is a fundamental aspect of a captive animal's housing and may affect a number of physiological and behavioural responses. This is particularly important for species such as X. laevis where cryptic camouflage is a fundamental defence mechanism. Here male (n=16) and female (n=20) X. laevis were housed in tanks with ecologically relevant (black) and non-relevant (white) background colours and physiological and behavioural responses observed. Higher levels of water-borne corticosterone were observed in tanks with a white background compared to a black background in females (p=0.047). Increased atypical active behaviours (Swimming: p=0.042; Walling: p=0.042) and a greater degree of body mass loss (p<0.001) were also observed in the white background condition. Together these responses are indicative of increased stress of X. laevis when housed in tanks with a non-ecologically relevant background compared to an ecologically relevant background and suggest refined tank background colour may improve welfare in this species.