The major statistical effects of the investigated factors on the development from in vitro oocyte maturation to cloned offspring. According to the results listed in Tables 3, 4, 5, 6, and 7, transitions between developmental stages (green rectangles) are found to be affected by statistically significant impact categories (purple ellipses). For each impact, the gain during a certain transition is given in percentage points (pp) and as compared to the corresponding reference. For example, the cloning efficiency (offspring out of transferred embryos, including only recipients that delivered) is increased by 1.8 pp in winter (from 3.5% to 5.3%), as compared to spring, which was used as reference. MSC: mesenchymal stem cells, 2d sel.: selected embryos for initiation of development on day 2 (2-cell to 4-cell stage), NT: nuclear transfer.