Embryo transfer (or E.T.) involves flushing and collecting embryos from super ovulated cows. Cows are given a series of injections to cause them to ovulate multiple eggs. These donor cows are inseminated and the embryos grow in the cow for 7 days. At day 7 we flush the uterus with a saline solution and collect the fertilized eggs or embryos. The harvested embryos are examined under a microscope, graded, and prepared for transfer or freezing. Embryos can be transferred fresh into recipients who are also 7 days past a heat. Embryos can also be stored by freezing them in liquid nitrogen and thawed and transferred at a later date.
The primary reason to utilize embryo transfer is to produce multiple offspring, hopefully daughters, from a cow of exceptional genetics. Without E.T. a good cow may give birth to 2 or 3 daughters in her entire lifetime. Embryo transfer allows the same cow to be flushed and her genetics / calves carried by other cows. If you get 3-4 pregnancies per flush and you flush her twice in a lactation for three lactation's, you can easily get 18 to 24 calves over her lifetime. It is possible to continually flush cows every 28 days for several years and gain even more calves.
Besides producing multiple calves to a single dam there are other uses for E.T. Embryos are easier to buy, sell and transport then a living-breathing animal. Especially with international trade, it is relatively simple to ship a frozen embryo. An embryo is washed to remove any bacteria and viruses prior to freezing. Live animals require extensive testing and quarantine for export. Embryos are used in research projects to acquire a large number of genetically similar animals. Embryo transfer is also useful in some cases of infertility. A high value cow that is unable to maintain a pregnancy can be flushed and a healthy cow can carry the calf. Or cows that don’t settle with A.I. might become pregnant to an embryo.