Supercows

Breeding better calves faster

Bovine sex has suffered for the sake of farmers' profits ever since artificial insemination replaced the old roll in the hay. The test-tube method allows the selection of genetically superior bulls, but there has always been a little problem with the cows. Even the best breeders normally drop only one calf a year. Now Mother Nature has been beaten at her own game by a new method that enables ranchers and farmers to turn the best of their cows into instant supermoms, capable of producing whole herds of exceptionally meaty or big-milking offspring.

The method is embryo transfer.

Top pedigreed cows, which sell for as much as $20,000, are injected with a hormone that causes multiple ovulation, the production of more than one egg. The eggs are then fertilized by artificial insemination and, about a week later, the live embryos--usually five, but sometimes ten or more--are withdrawn through the cervix by means of a catheter. Each embryo is then transferred, either by a six-inch incision in the side or directly through the cervix, to the uterus of a less perfect host mother, which carries the superior calf to full term. Since supercows, or "queen bees," can be bred seven times a year, each can produce 35 or more embryos annually. This can make the herd better but not significantly bigger since, even with embryo transfer, one cow is necessary for the gestation of each calf.

The cost: about $300 for consultation and the initial work plus $400 for every successful pregnancy. Dr. Kourken Bedirian, a Canadian physiologist who has pioneered the transfer of cow embryos, says that the success rate has averaged more than 60%. About 10,000 transferred calves have been born since the process moved from the lab to the barn in the early 1970s, and the procedure is rapidly spreading in the U.S. and Canada. For Bossie, motherhood will never be quite the same again.

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