Imagine that: There's no stopping randy pandy

Video footage shows giant panda Lu Lu before his marathon effort with Xi Mei.

They call him "the Enduring Brother".

For the second time in days, a particularly amorous male panda in China has smashed the record for longest mating session, zookeepers say.

The video of his 18-minute, three-second romp has gone viral in China, with bloggers praising the panda named Lu Lu for his enthusiasm, technique and - above all else - stamina.

To appreciate Lu Lu's accomplishment, one must consider some of the finer points of panda copulation. For instance, the fact that female pandas are fertile only once a year. And that the brief ovulation window lasts only two to three days.

So experts have resorted to some pretty zany ideas in the past to get the captive pandas in the mood - like making them watch "panda porn" and keeping a database of potent and performance-ready males.

Lu Lu - a bear Chinese scientists rescued from the wild in 1999 - set the first of his two recent records late last month. His encounter with a female named Zhen Zhen lasted seven minutes and 45 seconds, according to experts at the China Research and Conservation Centre of the Giant Panda in Sichuan.

Lu Lu's accomplishment was hailed far and wide, including by the Communist Party's flagship paper People's Daily.

This time around it was with a female named Xi Mei, who has a good record as a mate, having given birth to eight cubs since 2005.

Officials described the 18-minute romp as "quite successful".