1.   The FAO fears a mass extinction of native breeds which survive better in harsh conditions, and the loss of crucial disease-resistant genes.

2.   But their introduction in Kenya did contribute to the extinction of native breeds like the Kikuyu zebu that could have survived and prospered, Rege said.

3.   Earlier crosses between Brahman and native breeds were not resistant to local diseases and climate.

4.   The greatest threat, however, comes from farmers in poor nations discarding native breeds and switching to Western commercial livestock that is highly productive, the agency says.