A general guideline to embryo flushing and transfer

Embryo flushing and transfer makes it possible for cows with outstanding genetic potential to produce many more offspring than with simply using natural mating

- Janine Ryan

Embryo flushing is a means of artificial insemination (AI) used on farms to inseminate cattle and other livestock. Embryo flushing is different from traditional AI in that it involves a donor cow, a bull and a recipient cow, rather than only a recipient cow and bull as in AI. Prof Tom Troxel, head of the department of animal science at the University of Arkansas in the US, explains that embryo transfer is the process of removing one or more embryos from the reproductive tract of a donor female and transferring them to one or more recipient female animals.

“Embryos also can be produced in the laboratory via techniques such as in vitro fertilisation or somatic cell cloning.

“But the actual transfer of an embryo is only one step in a series of processes that may include some or all of the following: superovulation and insemination of donors, collection of embryos, isolation, evaluation and short-term storage of embryos, micromanipulatio and genetic testing of embryos, freezing of embryos and embryo transfer,” Troxel says.

He explains that embryo transfer in cattle has become considerably popular with dairy and beef producers over the past decade. “Most of the applicable embryo transfer technology was developed in the 1970s and 1980s, [but] the history of the concept goes back much further.”

According to Troxel, Walter Heape was the first to perform an embryo transfer in 1890, when he transferred the embryos of two Angora rabbits into a gestating Belgian rabbit.

“The Belgian doe produced a mixed litter of Belgian and Angora bunnies,” he says.