Selection of the donor cell is critical for the success and efficiency of animal cloning.To establish a preliminary procedure for porcine cloning,this study was undertaken to systematically examine the effects of serum starvation and passage numbers of the donor cells on the development of nuclear transferred pig embryos.When donor cells were cultured for 0 d,2 d,4 d and 8 d under 0.5% serum starvation,the cleavage rate of reconstructed embryos was not significantly different (P>0.05),but the blastocyst formation rates at 2 d and 4 d were significantly higher than the other groups (P＜0.05).Cells were passaged for 0,2,4,8 generations and used for nuclear transfer.The results showed that the cleavage rates of reconstructed embryos were not significantly different among donor cell generations (P＞0.05),but significantly higher than that of the unpassaged cells (P＜0.05),with cells passaged for 6 generations showing the highest cleavage rate and blastocyst formation rate (86.29% and 23.36%).Reconstructed embryos with donor cells cultured under serum starvation for 2 d and passaged for 4 generations were transferred to six surrogates.Three surrogates returned to estrus,one was abortion after transplantation for 45 d and six cloned piglets were obtained from one of the two remaining pregnant pigs.