Could farming rhinos save them from extinction?

Rhino horn is worth more than gold or heroin by weight, so poachers often kill the animals and cut off their horns.

It's illegal to sell the horn on the international market, but John Hume, a rhino farmer in South Africa, argues that if it were legal, poachers would breed rhinos rather than kill them.

But it's a highly controversial argument.

Trophy: The Big Game Hunting Controversy is on Storyville on BBC4 on Monday 29 January at 21:00, and afterwards on iPlayer..