The hazards of cloning were revealed yet again after scientists in the us had to put to sleep one of two banteng calves they had cloned. The researchers took the step as the animal was "abnormally large'. While the "healthy' calf was normal in size (20 kilogrammes or kg), the other one weighed about 36 kg.

Scientists at the us -based Advanced Cell Technologies cloned the calves from a banteng that had died more than 20 years ago. Bantengs, found in Asia, are an endangered species of wild cattle. The scientists said the attempt was part of a process to resurrect endangered animals through cloning.

The cloning technique entails the risk of creating an abnormal placenta