The number of animals used in research should be limited as much as possible. Among cloned animals, genetic variation is minimal and to the extent that behaviour is genetically determined inter-individual variability is expected to be higher among naturally bred animals. However, the cloning procedure per se might affect the resultant phenotype leading to phenotypic variations independent of the genetic background. Recently, cloned Göttingen minipigs carrying a mutation for Alzheimer's disease have been produced. In order to document the development of Alzheimer's disease symptoms, these pigs were subjected to a behavioural test of memory, the spontaneous object recognition test, from an early age. At ages 1 and 2 years no evidence of memory decline was found, yet the data showed striking behavioural variability among the cloned groups. The aim of the present study was to investigate effects of genetic homogeneity on variability of cloned minipigs compared with non-cloned controls regarding behavioural variables in a cognitive test, namely the spontaneous object recognition test. Significant differences in the variability between the cloned and control pigs were found in five out of 24 behavioural variables. The clones showed lower variability for four of the measures, whereas the variability was increased for one variable. No significant difference between the cloned and the control group was found for the remaining 19 variables (79%). In 14 of these, the standard deviation was numerically greater for the control group compared to the cloned group, indicating that variation may be less in cloned animals, but not demonstrable with the small group size of the present study (n=6 for each of the two groups tested). Overall, this study failed to show unambiguously that variability in these behavioural variables in cloned minipigs is less than in naturally bred control subjects and therefore does not directly support the hypothesis that cloning may be used to replicate animals in order to reduce group size in experimentation animals.
|Publication Title||Applied Animal Behaviour Science|
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