A one-step method for direct nonsurgical transfer of frozen-thawed bovine embryos.

One impediment to the more widespread use of freezing as an adjunct to embryo transfer in cattle has been the method used to remove the protective compound from the thawed embryos. Recently, a method has been developed that permits bovine embryos to be diluted out of the protective solution within the plastic straw in which the embryos were originally rrozen and thawed. The method requires only about 10 minutes to perform and does not require a microscope or other laboratory equipment. Therefore, frozen bovine embryos can be thawed, diluted, and transferred nonsurgically into recipient cattle under conditions quite similar to those used for artificial insemination. A large number of field trials of this method have been performed during the past 2 1 2 years. A total of 327 pregnancies have been established by the nonsurgical transfer of 1259 embryos that had been frozen, thawed, and diluted by this method.