Banteng (Bos javanicus) embryos and pregnancies produced by interspecies nuclear transfer

The banteng (Bos javanicus), a member of the bovidae family, is currently listed as threatened by the IUCN Red List and it is estimated the total world population is <10,000 animals. In exotic or endangered species, the lack of oocytes and recipients precludes the use of traditional somatic cell nuclear transfer (NT), and an approach such as interspecies NT may be the only alternative to produce embryos and offspring. A total of 348 enucleated domestic bovine oocytes were reconstructed with either male (Treatment A) or female (Treatment B) adult banteng fibroblasts and a total of 103 bovine oocytes were parthenogenically activated as a control (Treatment C). There was no significant difference in fusion rate (68 versus 77%) between Treatments A and B. Of fused couplets, those in Treatment A had greater (P < 0.05) cleavage (67 versus 51%) and blastocyst (28 versus 15%) rate than Treatment B. Of a total of 24 blastocysts transferred into 12 domestic cattle recipients from Treatment A, two pregnancies (17%) were established with heart beats detectable at 30 day by rectal ultrasonography. No pregnancies resulted from the transfer of 14 blastocysts from Treatment B. Both pregnancies were subsequently lost, one between 30 and 60 days and the second between 60 and 90 days of gestation. The bovine cytoplast supported mitotic cleavage of banteng karyoplasts, and was capable of reprogramming the nucleus to achieve blastocyst stage embryos and pregnancies in exotic bovids.