Li Xin's life has been extremely busy this summer, after 24 cubs were born at the Siberian Tiger Park in Harbin, Heilongjiang province.

Since the 40-year-old became a breeding expert at the park in 2004, his life has been closely related to the big cats.

"I am responsible for feeding the tigers and monitoring their health, as well as cleaning out their living quarters," he said. "These large animals look fierce, but sometimes they are also naughty and lovely. After a long time together, we are just like interdependent friends."

The mating season for Siberian tigers usually falls in January and February. Every year during the birthing season, which runs from early April to late June, Li and three other breeding experts — Jia Teng, Song Zhiyang and Zhang Xu — take turns to work 24-hour shifts to monitor the pregnant tigers, which are moved to separate living quarters in a special area about one month before they give birth.

"Every day, the breeders carefully disinfected both the indoor and outdoor living areas," Li said. "The temperature in the living quarters stayed at 17 to 20 C, which was comfortable for the animals."

The experts paid great attention to the tiger moms, checking their health by monitoring their appetites and daily activities during the 105-to-110-day pregnancy period.

In addition, they prepared an ample supply of nutritious food — including milk and eggs, as well as several kinds of vitamin pills — to help maintain the animals' strength.

This year, eight tigers gave birth to cubs, including twins, triplets, quadruplets and quintuplets.

"Usually, Siberian tigers give birth to two to four cubs at a time, but it is rare to see healthy quintuplets" Li said, noting that on May 10, a tiger gave birth to five cubs in one batch.

Most of the young mothers have no experience of nursing cubs, so the four experts took on the task of feeding the young tigers.

"The cubs' body temperature dropped rapidly as their mothers did not take care of them after giving birth, so they had to be sent to the incubator and observed for 24 to 48 hours. After their body temperature returned to normal, they were taken to a designated room for artificial feeding," Li said.

"They needed to be fed with milk every three hours for the first week after birth," he added, noting that the milk was made from a commercial tiger formula powder. "We also had to pay great attention to their health by monitoring their appetites, body temperatures and feces." Li said that when the cubs are older, they will be fed chopped meat.

Siberian tigers are a critically endangered species, with fewer than 500 believed to be roaming free in the wild. They mainly live in northeastern China and eastern Russia.