Health supplements to tackle a calcium deficiency could mean it is third-time lucky for efforts to persuade Edinburgh Zoo's giant pandas to mate successfully.

Vets have revealed the zoo's male panda Yang Guang is receiving supplements with his food to help boost his fertility.

Staff are reported to have told visitors to the zoo about the dietary supplements and revealed the previously undetected calcium deficiency may have been behind female panda Tian Tian's unexpected hostility to her intended partner during the three-day mating period last April.

Despite conceiving, the zoo announced in October that she had lost her cub. The 11-year-old male is said by staff to be back to full health now and is performing headstands, regarded as a display designed to attract Tian Tian.