Beef Cattle Embryo Transfer
Commercial beef cattle embryo transfer was not very popular until the 1970's. Non
surgical methods of transferring embryos were developed in 1970’s and gained recognition soon. Artificial
insemination allows us to utilize the reproductive potential of genetically superior bulls while embryo transfer
allows us to utilize the reproductive potential of cows that are genetically very valuable.
Beef cattle embryo transfer needs much expertise,
experience, time and effort. Selecting genetically superior donor cows is very critical. Some basic points are kept
in mind while choosing the right donor cow: Cow should have regular heat cycles and her reproductive age must be
less, she should not have had more than two breedings per conception, she should have given birth to calves each
year, she should be healthy and fertile, she should not have any reproductive or calving difficulties, she should
be free from any genetic defects. Nutritional needs of the cow must be adequately met. She should neither be fat
nor thin. Keeping all these things in mind, donor cows are selected.
Next step is the superovulation of cows, when they are treated to release multiple eggs
in single estrus. The cow is then inseminated at 12, 24, and 36 hours after the start of the standing heat. Semen
is placed in the body of the uterus at the front of the cervix. Proper placement ensures high chances of
conception. Next step is embryo collection which can be done either surgically or non-surgically. Non-surgical
method is however more popular. Embryos are harvested 7 to 8 days after estrus. A small synthetic rubber catheter
is used to collect embryos. It is inserted through the cervix. Cow is not harmed at all during all this process. It
takes no more than half an hour to complete the embryo transfer. A special fluid is flushed in and out of the
uterus. One liter of fluid is used to fill the uterus and embryos are flushed with this liquid. Embryos can be
recovered after 30 minutes using a microscope. Their quality is then assessed based on their shape, blastometers,
cytoplasm, vesicles, zona pellucida and diameter.
Cows to which the embryos are transferred are also selected very carefully. These cows
must also be healthy, without any calving difficulties and properly nourished. It is also important that conditions
inside recipient cow are similar to those in donor cows for successful conception. Embryo is first transferred into
a 1/4-ml insemination straw. The embryo is then transferred to the cow through cervix. Care must be taken not to
harm or infect the reproductive tract of the recipient cow. Beef cattle embryo transfer is a very expensive process
and must be carried out very systematically and carefully.