The pandas that reside in the nation’s capital got to snack on a special anniversary cake as the Smithsonian’s National Zoo and Conservation Biology Institute marked 50 years since the exchange agreement with China.

Over the weekend, the Washington, D.C.-based zoo served its beloved pandas Mei Xiang, 23, and her cub Xiao Qi Ji, 1, frozen "fruitsicle" cake made from diluted apple and pineapple juice. 

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The treat was topped with sweet potato, apple, carrot, pear, sugar cane, banana and yellow groove bamboo. A vibrant number 50 was attached to the top of the cake.

The Associated Press reported that the mother and son panda duo devoured their cake in about 15 minutes.

Mei Xiang’s mate, Tian Tian, 24, was served a similar fruit cake later that afternoon. 

During the "pandaversary," as zoo officials called it, Chinese ambassador Qin Gang said the panda exchange program was "a symbol of the friendship" between the U.S. and the People’s Republic of China. 

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The program got its start in 1972 when Chinese Premier Zhou Enlai gifted a pair of pandas to the National Zoo after hearing first lady Patricia Nixon enjoyed seeing pandas during her trips to China, according to Lonnie G. Bunch III – the 14th secretary of the Smithsonian Institution.

Twelve years later, the program was adjusted from a gifting program into a loan program. Under this change, pandas bred in China can only be loaned to an international ally for 10 years.

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Mei Xiang and Tian Tian are due to be returned to China in 2023, according to the National Zoo.

Pandas are native to southwest China.

National zoo pandas Mei Xiang, Xiao Qi Ji

Giant pandas Mei Xiang (left) and her cub Xiao Qi Ji eat a fruitsicle cake in celebration of the Smithsonian's National Zoo and Conservation Biology Institute's panda exchange program's 50th anniversary. (AP Photo/Jose Luis Magana)

Panda bears have a lifespan that ranges between 15 and 20 years in the wild, and about 30 when kept in captivity. 

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The Smithsonian’s first panda, Hsing-Hsing, lived to the age of 28. The world’s oldest panda in captivity, Jia Jia, lived until 38 at Ocean Park Hong Kong, according to Guinness World Records.