?If we?re going to keep them here we?re going to have to protect them,? says William Tell Holdings CEO Barry Lok about the white rhinos on his farm northwest of Johannesburg.

Protecting an investment … the rhino rancher Barry Lok. Photo: Bloomberg

Barry Lok grimaced as he gazed at the rotting carcass of his rhino bull, Kruger, lying under a tree on his farm north-west of Johannesburg. His heart had been pierced by a poacher's bullet and his horn, worth its weight in gold, sawn off to be sent to Asia.

Kruger's death spells more than the loss of a beast Lok loved for its ''prehistoric beauty''. Lok must now either pay heavily for more security or sell livestock and contribute to the species' demise.

Rhino poachers in South Africa, home to about 90 per cent of the world's population of the endangered animals, are increasingly targeting private game owners as rhino killing rises towards a record. Demand is rising in China and Vietnam, where rhino horn powder is believed to cure cancer. Last year 125 rhinos were poached from private farms in South Africa, a 52 per cent increase from 2010.

Members of the Pilanesberg National Park Anti-Poaching Unit stand guard as conservationists and police investigate the scene of a rhino poaching incident April 19, 2012. Elephant and rhino poaching is surging, conservationists say, an illegal piece of Asia's scramble for African resources, driven by the growing purchasing power of the region's newly affluent classes. In South Africa, nearly two rhinos a day are being killed to meet demand for the animal's horn, which is worth more than its weight in gold.

Worth more than its weight in gold ... the scene of a rhino poaching incident is guarded by members of the Pilanesberg National Park Anti-Poaching Unit in South Africa. Photo: Reuters

''If we're going to keep them here we're going to have to protect them,'' Lok, 54, said in an interview at his 2000-hectare farm. ''Bluntly, you'd have to sell the rhinos to pay for it. That's not sustainable.''

The farmers need rhinos to run their hunting and game viewing businesses, which can charge a premium if their properties boast the so-called big five: rhinos, elephants, buffaloes, lions and leopards. Some, like Lok, breed the animals for sale to ranchers.

By targeting rhinos, poachers are endangering conservation efforts while also threatening South Africa's billion-dollar wildlife ranching industry. A 1970s law that gave farmers in the country ownership of wildlife on their land has led to the tripling of animal populations, according to Wildlife Ranching South Africa, an industry organisation.

Revenue at game farms has risen by an average of 20 per cent a year over the past 15 years. More than 10,000 private game farms now cover about 20 million hectares, according to the official journal of Wildlife Ranching South Africa. That's almost three times the land of government conservation areas.

The fear of future attacks has driven Lok to hire four guards at a cost of 40,000 rand ($5000) a month in salaries, training and equipment.

''The rhino is worth more dead than alive,'' said Pelham Jones, head of the Private Rhino Owners Association, which represents most of the country's 400 rhino ranchers, in an interview this month. ''The investor in product 'rhino' says, hey, this isn't such a good idea any more.''

White and black rhinos were brought back from the brink of extinction in South Africa in the 1960s to a stable population of close to 20,000. Most of them are the larger white rhinos, which can weigh more than two tonnes.

The rise in killings dates to 2009, when South Africa imposed a moratorium on the domestic trade in horns to match an international trading ban, according to the Endangered Wildlife Trust in Johannesburg.

''The ban actually becomes the cause of the problem rather than the solution,'' said Michael T'Sas Rolfes, an environmental economist who is advising the Department of Environmental Affairs on research into lifting the ban. It ''is a disaster, because the price skyrocketed and it attracted organised crime''.

The number of rhinos poached so far this year is already double the total killed illegally in the eight years until 2007, according to government figures. Standing at 181 as of mid-April, it probably will hit a record this year. A rhino is poached in South Africa about every 18 hours, according to the International Rhino Foundation, a non-profit organisation in Florida.

Rising affluence in south-east Asia is stoking demand for rhino horn. The material, made from substances similar to hair, is usually ground into powder, mixed with water and drunk.

In Vietnam horns can trade for as much as $US65,000 a kilogram, says T'Sas Rolfes. With gold about $US1646 per ounce last week, a kilogram of gold is worth a bit more than $US57,000.

The bulk of poached rhinos, more than 70 per cent, still are killed in government parks. By April 20, 111 had been been poached in the Israel-sized Kruger National Park this year, compared with 252 last year. The government has deployed the army, improved rangers' equipment, arrested scores of suspects and shot poachers dead.

Next is a plan to tighten hunting laws, monitor wildlife shipments more closely and increase ranger numbers, says the Environmental Affairs Minister, Edna Molewa.

South Africa this year barred Vietnamese nationals, who apply for nearly 60 per cent of rhino-hunting permits, from hunting the animals on the grounds that it cannot be assured the horns won't be resold. Legal hunting gives a value to rhinos, encouraging their breeding by private owners.

Hunters are willing to pay as much as 500,000 rand for the right to kill a large rhino bull on a farm.

The University of Pretoria has a database with 3000 samples of rhino DNA, which can help connect recovered horns to poaching.

For Lok, poaching was ''something that happened to others'' until the death of Kruger. Treating two other rhinos that were shot and wounded by poachers earlier this year has cost him thousands of dollars in helicopter and veterinary fees.

John Hume, a hotel magnate in South Africa who says he is also the world's biggest private rhino owner, will triple his security costs this year. He is hiring 40 new guards, alarming his 11,500-hectare properties and installing cameras designed to tell the difference between animals and humans. The 70-year-old dehorns all of his 762 rhinos.

Still, six of his animals were killed by poachers last year, he says. Hume is promoting a campaign to legalise trade in rhino horn.

''If we made money out of the rhino's horn, not only would it contribute to stopping the poaching, it would get people to rear and buy rhinos,'' Hume says. ''It would be the best news the rhino could be possibly get.''

Petitioned by rhino owners, the Environmental Affairs department is due to complete the research into the viability of legalising the trade within South Africa by August.

For now private owners face the stark choice of protecting their rhinos or losing them to poachers.

''Game farming has turned into a war,'' said Lok, lamenting the loss of a ''paradise'' he created with his wife and three sons. ''How can you protect them in the face of such demand?''

Bloomberg