A zoo is giving its animals contraceptives to ease pressure on space amid an outbreak of TB.
Paignton Zoo in Devon cannot send any animals to other zoos because of movement restrictions to prevent the spread of the disease.
But vets fear the zoo could run out of space as the number of animals increases, so are trying to curb reproduction.
TB was found at Paignton last summer when 11 antelope were put down.
Head vet Ghislaine Sayers said: "We must prevent overcrowding but we must still be in a position to take part in breeding programmes when the restrictions are lifted, so we need temporary solutions."
Contraception is being given to 60 mammal species with injections, tablets, implants and IUD coils.
Lions have to be anaesthetised with a dart gun before they are injected.
Asiatic lion Lucifer's partner Maliya is among the zoo's lionesses that have been injected with contraceptive.
The zoo's breeding programme, in which it sends animals to hundreds of zoos in England and around the world, has been halted since the outbreak was discovered last August.
Animal testing has been continuing since the outbreak and no other animals have been affected.
It can restart its breeding programme by the end of the year if it is given the all-clear.
The zoo has also beefed up its fencing to keep out badgers, which it says are the "likely" carriers of the disease into the premises.