Effect of genetic homogeneity on behavioural variability in an object recognition test in cloned Göttingen minipigs

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.