The creatures are native to the forest floors of Kenya and Tanzania, with adults weighing around 1.54 lbs (700g) and capable of running up to 15 mph (25km/h).
Tyler Whitnall, managing director of Hertfordshire Zoo, said: “To have the first-ever black and rufous sengi birth in the UK is an incredible feeling.
“To see them successfully breed so quickly is a testament to the world-class care provided by our team.”
He added: “These pups are growing incredibly fast and are already showing the same high-energy, inquisitive traits as their parents.”
The newborns are currently being monitored by the zoo’s veterinary team and, while spending much of their time in their nesting area, are expected to be on view to the public in the coming weeks.
