(CN) Cloning to beef up stock breeding

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China Daily 11th March 2002

http://www1.chinadaily.com.cn/cndy/2002-03-11/60225.html(HE SHENG)

 

Chinese research team announced on Thursday in Beijing they had succeeded in

cloning calves from adult cells, using a technique similar to what produced

the cloned sheep, Dolly, in Britain four years ago.

 

All the calves were cloned from a bull and a high-performing dairy cow by

fusing an adult cell with an egg.

 

The researchers took cells from the ears of the bull and the cow, combined

the cells with oocytes of the surrogate mother, then implanted the cloned

embryos into the womb of the cattle.

 

Twelve surrogate cows gave birth to 14 calves between January 18 and

February 11 this year in the Zhongda Animal Embryo Engineering Centre in

East China's Shandong Province.

 

DNA examinations proved that the calves - nine of which have died - are all

genetically identical to the two providers without any genetic linkage to

the surrogate mother, according to Chen Dayuan, chief scientist of the

research.

 

The surviving dairy cows are also distinguishable by their black and white

markings with almost the same size and pattern.

 

The five calves still alive are said to be in good health.

 

China has become the fourth country, behind Japan, New Zealand and the

United States, to master techniques to create cattle by cloning, Chen said.

 

He acknowledged that they still need to tackle a lot of problems, including

low rates of pregnancy and survival, and a high rate of miscarriage.

 

" There is still a long way to go before the technology is eventually used in

commercial production, " Chen said.

 

A total of 980 eggs were cultivated, 261 of which developed into blastulas,

the early developmental stage of an animal.

 

Only 26 of 112 cows became pregnant after 230 blastulas were implanted into

their wombs, and only 12 finally gave birth.

 

Low pregnancy rates are almost unavoidable unless new techniques are

invented.

 

Still, some progress has been made through research, such as shortening the

maturity period of the oocytes, according to a scientist panel organized by

China's Natural Science Foundation to review the research.

 

Embryologist Tong Dizhou initiated China's first research in cloning fish in

the 1960s.

 

Chinese scientists have sped up research in cloning adult animal cells since

Dolly was born in Britain, hoping future techniques may benefit the

country's underdeveloped stock breeding industry.

 

Dairy production is believed to have huge potential in China since milk

consumption among China's 1.3 billion people is only 10 per cent of the

average of some Western countries.

 

It is hoped that the new technology will help breed cattle for higher-grade

beef, greater milk production and medical purposes.