Table 4  Cloning competence of cells from donor animals of different ages
Donor age  No. Oocytes used  (%) Development
Cleavage  Blastocyst
Fetus (D57)  630  82  48a
New born  302  76  51a
2 years  158  79  38b
10–12 years  424  73  35b
16 years  269  63  37b
Numbers with different superscripts within columns are significantly different (P < 0.05).