Technical Note: Transfer of caprine blastocysts vitrified by the open pulled straw (OPS) or the solid surface procedure and warmed in sucrose-free medium

The present paper outlines ways of non-surgical collection and semi-laparoscopic transfer of caprine embryos. Two different ways of embryo cryo-preservation by way of vitrification are described; the open pulled straw (OPS) procedure, known to be well suited and the solid surface procedure called for in situations where contact between embryos and non-sterile liquid nitrogen is to be avoided. Based on 13 transfers of OPS-vitrified and 9 transfers of solid surface-vitrified blastocysts (2 blastocysts/recipient) it was shown that either procedure is applicable (54% vs. 56% pregnancy- and 39% vs. 44% kidding rate). Furthermore the experiment showed that warming of vitrified embryos may be accomplished by one-step procedure (88% transferable post-warming embryos), opening up the possibility to transfer vitrified embryos under field conditions.