Panda cub will need paternity test It means that should Tian Tian give birth, either of the male pandas could be the father and if she gives birth to twins, then they could have different fathers. Geneticists will instead carry out a DNA test on the cub or cubs once they reach around one to three months old. Iain Valentine, director of giant pandas for the Royal Zoological Society of Scotland, said: "In the wild, pandas have a multiple mating strategy so a female would mate with several males and there would be competition to fertilise the egg. What we did in the artificial insemination was to replicate that to make it as natural as we could. The complication is that we will need to do paternity tests to determine the cub's lineage for breeding in the future. The other panda had been wild caught and so is very important genetically for the Chinese. Tian Tian underwent the artificial insemination procedure in April this year. Female giant pandas are only in season for 36 hours a year, giving them only a short window of time to mate in. Keepers at Edinburgh Zoo made extensive efforts to increase the chances of Tian Tian mating with Yang Guang, who lives in an enclosure next door. The pandas underwent daily tests to find the right moment to bring them together, while keepers dabbed each of the panda's urine around the other's enclosure to get their passions flowing. The animals were given short glimpses of each other through a grate and the male was given strength training to prepare him for the task of mating. Staff even played soothing easy listening radio to help get the male in the mood. However, despite this the couple failed to mate for the second year in a row, but before Tian Tian's fertility window ended, the keepers stepped in to artificially inseminate her. As they could not get enough of Yang Guang's sperm, they also used a sample from a panda called Bao Bao, who lived at Berlin Zoo and had previously been at London Zoo until 1993. He died in Berlin last year. Tian Tian and Yang Guang are currently the only giant pandas in Britain and are on loan from China for 10 years. The last panda in the UK was Ming Ming, which was sent back to China from London Zoo in 1994. Mr Valentine said Tian Tian was now showing encouraging signs that she is pregnant but it is still too early to be certain that she will give birth. Female pandas can undergo pseudo-pregnancies, where their hormone levels change and they start to sleep more and put on weight after their fertility window even if not pregnant. Tian Tian had a pseudo-pregnancy last year after failing to successfully mate. This year, however, she is moodier and has started building a straw nest beneath her sleeping platform. She has also started bleating, a sign that Chinese scientists have said is encouraging. Early results from a pioneering test, known as a CP test, developed by researchers at Memphis Zoo is also suggesting she is pregnant. Mr Valentine said: "This CP test does seem to be pointing towards pregnancy but we need another couple of weeks of samples to know she goes to full term as even if she is pregnant she could lose the pregnancy. This is still an experimental test so we cannot rely upon it, but we are also seeing some behavioural signs we didn't see last year when she had a pseudopregnancy. Even if Tian Tian does give birth this year, however, the public will not get to meet the cub or cubs until 1 January next year.