Since the report of Cibelli and colleagues, many laboratories have compared nuclear transfer using donor cells with and without serum starvation. In our study, we used cells from a 17-year old male Japanese Black beef bull and found that serum starvation was not required for successful cloning because cloned embryos and animals were produced from cells not subjected to serum starvation (Table 1) [16]. Furthermore, serum starvation did not have a beneficial effect on the blastocyst development of cloned embryos.