Isiolo - Poachers slaughtered a rhino in one of Kenya's best guarded wildlife parks, officials said on Tuesday, in a brazen attack highlighting the risks gunmen are taking during a surge of killings."Poachers infiltrated Lewa's borders during the full moon on 17 November and killed Meluaya", a 17-year-old black rhino suspected to have been heavily pregnant and with a two-year-old calf, Lewa Wildlife Conservancy said in a statement."Both horns were removed and the poachers got away with them."Lewa's more than 60 rhino are monitored every day by special surveillance teams, part of a security force of 150 staff. They include armed rangers and dog handlers who patrol with bloodhounds around some 150km of electric fence surrounding the park.Conservancy personnel also use aerial surveillance to monitor the animals and try to track poachers.Lewa is privately owned but run as a non-profit dedicated wildlife area, and came to world attention when Britain's Prince William stayed there with Catherine before proposing marriage.Poaching has risen sharply in Africa in recent years, with rhinos and elephants particularly hard hit.Earlier this month, Kenya's Attorney General Githu Muigai said the country had lost 90 elephants and 35 rhinos to poachers so far this year.Asian consumers who acquire smuggled rhino horn - which is made of keratin, the same material as human fingernails - believe that it has powerful healing properties.Isiolo county deputy governor Mohamed Guleid condemned the killing and pledged to "do everything to protect our national heritage and pursue the killers".Earlier this month Kenya started inserting microchips into rhino horns. Wildlife officials plan eventually to microchip all rhinos in the country, just over 1 000 animals altogether.Inserting the chips entails shooting the rhino with a tranquiliser dart fired from a helicopter.