Artificial induction of twinning in cattle by means of supplemental embryo transfer

Mixed-breed twin production by contralateral direct-transfer of male embryos to beef cow recipients bred to GnRH-based, fixed-time AI

“…Rates of pregnancy and twinning rates were similar to previous reports involving various combinations of ET and natural service (Anderson et al, 1979;Renard et al, 1979;Holý et al, 1981;Sreenan and Diskin, 1989;Sinclair et al, 1995;Sakaguchi et al, 2002). In agreement with others, there was no significant difference in pregnancy rates when 7-d embryos were transferred on Days 6 or 7 (Sakaguchi et al, 2002).…”

“…Most male embryos are deemed surplus in the dairy industry (Shea, 1999), and therefore are relatively inexpensive. Mixed-breed twins have been successfully produced by ipsilateral (Sakakibara et al, 1996) or contralateral (Holý et al, 1981) transfer of embryos to recipients bred 6 to 8 d earlier by natural service or artificial insemination following estrus detection (Sinclair et al, 1995;Sakaguchi et al, 2002). If calves are destined for beef production, free-martinism is not an issue (Horton et al, 1980;Gregory et al, 1996).…”