What is a cow-stopper embryo? is the question answered by Paragon Vet, Tom Redmayne.

It is not unusual for some cows to repeatedly fail to hold in calf and continue to return to oestrus every 21 days. Using a cow-stopper (repeat breeder) embryo could be an effective way to solve this problem. Cow-stopper embryos are transferred in to cows in addition to serving or artificially inseminating them. The addition of the cow-stopper embryo can help the establishment and recognition of pregnancy. An embryo (originally frozen at 7 days old) is thawed and implanted 7 days post oestrus/service. Matching the stage of cow-stopper embryo to the stage the cow is in her reproductive cycle is critical to improving conception rates.

Which cows require cow-stopper embryos?

Cow-stopper embryos are usually implanted in cows that have been served and/or artificially inseminated more than 3-4 times and have returned to oestrus or had a negative pregnancy diagnosis. Cow-stopper embryos are more commonly used in the dairy industry where there is the greatest need for a cow to produce a calf every year in order to continue milk production. Cow-stopper are sometime used in valuable beef cows that have proven difficult to get in calf.

How is the embryo implanted?

The day of implantation is 7 days after the cow has been served or artificially inseminated. The insertion of a cow-stopper is a non-surgical procedure. On the day an assessment of the repeat breeder cow’s ovaries will be made. As long as the cow has a corpus luteum (a small structure that is formed when the cow releases an egg of her own) on one of the ovaries, the cow-stopper can be implanted. The embryo is implanted using the standard technique used for embryo transfer. This involves using a fine catheter to allow the embryo to pass up through the uterus and in to the uterine horn. The procedure is carried out under epidural anaesthesia to prevent discomfort for the cow. The cow-stopper can be put in on natural or synchronised heat.

Results from cow-stopper embryos?

· 50 percent of cows given a cow-stopper become pregnant

· The majority of calves born will have parentage belonging to the cow’s original service or artificial insemination.

. A smaller percentage will have a calf born from the cow-stopper embryo implanted.

· Around 15 percent will have calves born as twins, one to the original service and one to the cow-stopper embryo.

For more information regarding cow-stopper embryos please get in touch with Paragon Advanced Breeding: 01768 483789