Conventional outdoor breeding herds have encountered a number of problems caused by extremes of temperature and excessive exposure to sunlight leading to heatstroke and sunburn.

"The cow-calf operator should have a good year," said Mr. Thorpe, referring to the ranchers who keep the basic breeding herds.

The zoo has the largest breeding herd of Asian elephants of any zoo.

Sorely tempted, the two old bulls left the fence and ambled back to the breeding herd that waited patiently for their decision amongst the thorn trees.

Soon we heard the crashing of acacia trees and the snapping of branches - about 10 elephants, a small breeding herd, said Phil.

Because very few bulls are needed to breed with many cows and heifers and to form a complete breeding herd, most male cattle are used for meat.

The first known breeding herd of Chilean llamas on the African continent, donated by the family of the Foundation's Vice Chairman.

Last year Zimbabwe was estimated to have about 2,000 black rhinos, the world's last viable breeding herd.

The species, descended from the Imperial Herd of China, now enjoys the largest breeding herd in the world at Woburn.

Port Lympne also houses the critically endangered Sifaka and the largest breeding herd of Black Rhinoceros outside Africa.