This paper discusses whether acquiring genetically modified animals or embryos from an existing strain, as opposed to generating a new founder, is to be preferred, with respect to animal use and animal distress. To address this question, the results of an inventory performed in 17 Dutch research institutes are presented. it is argued that the acquisition of embryos is to be preferred to the acquisition or generation of animals. Furthermore, it is argued that patenting may lead to the generation of already existing strains.