(Portland, OR) -- The Oregon Zoo is announcing the birth of a rare African antelope at its facility. The bontebok were once considered among the most imperiled mammals on the planet. Zoo officials say the female bontebok that gave birth initially wasn't nursing the calf, so zoo keepers gave the calf a blood transfusion from the father so it had immunities. Zoo keepers then bottle-fed the baby until the new mother learned how to nurse the calf. It weighed just under 18 pounds at birth and now weighs 34 pounds. Once she gets larger, she'll be allowed out into the zoo's Africa savanna area.