Gene transfer experiments in cattle.

Various methods for gene transfer in cattle are described. Four vectors containing (1) the bovine papilloma virus DNA, (2) the alcohol dehydrogenase gene of Drosophila melanogaster, and the human (3) and the bovine (4) growth hormone gene were used for gene injection in bovine zygotes. The period between 78 and 82 h after prostaglandin treatment was determined as the optimum time for collection of bovine zygotes. A total of 802 eggs was obtained from 74 successfully superovulated heifers. The foreign DNA was injected into the pronuclei of 156 (Construct 1), 130 (Construct 2), 62 (Construct 3) and 250 (Construct 4) centrifuged zygotes. An average number of 12 zygotes per recipient heifer was transferred into one oviduct. The eggs were recovered after 14 days (Constructs 1 and 2) for analysis or after 7 days (Constructs 3 and 4) respectively for transfer into final recipients. After the transfer into 23 recipient heifers of 43 embryos (Construct 4), 14 calves were born and 1 fetal monster was isolated. According to dot-blot hybridization the total rate of efficiency of gene transfer was 3.2%, 6.9%, and 0.8% for Constructs 1, 2 and 4, respectively.