New technique results in cloned calf

Researchers at the Monash Institute of Medical Research and Genetics Australia Co-operative have cloned a cow using the technique of serial nuclear transfer.

It's the first time that the technique, which has previously been used to clone mice and pigs, has been applied to cows.

Serial nuclear transfer involves a two-step cloning process -- first, a donor cell from the animal to be cloned is inserted into an enucleated egg, then the cloned embryo is fused with a fertilised egg, also lacking its nucleus. The second fusion step is thought to provide additional signals to the cloned nucleus that improve the environment for the earliest stages of foetal development.

"By repeating the nuclear transfer we hoped to improve the reprogramming of the fused donor cells and produce healthier embryos which are more likely to proceed to live births," said PhD student Vanessa Hall, who performed this research as part of her PhD project.

Hall said that while only one successful birth had been achieved so far, there were indications that the two-step serial nuclear transfer method was more efficient than the traditional nuclear transfer technique which typically requires hundreds of cloned embryos to be implanted into hosts in order to get one live birth.

But using this technique, only 13 cloned embryos were transferred into hosts, with one pregnancy resulting in the birth of a healthy cloned calf, Brandy, in December.

According to Hall, the researchers at MIMR and Genetics Australia are interested in whether the technique can be used to improve the efficiencies of cloning enough to make it a viable tool for use by farmers.

"SNT and other cloning techniques are designed to complement natural breeding strategies. Over the next decade, as higher success rates are established, these scientific developments could provide farmers with the option of some powerful new reproductive tools. Cloning allows for the rapid dissemination of elite genetics from both male and females lines," she said.