The buildings do not even look like farms. They are huge grey concrete blocks, many storeys high, which stand side by side in the middle of what might look like a quarry, a “hole” of red earth dug in the heart of a mountain.

We are on the Yaji mountain, which in Chinese means “sacred”, a few kilometres south of the city of Guigang in southern China. What we are looking at is the tallest pig farm in the world; units up to nine storeys high housing thousands of pigs, with construction of a 12-storey pig unit under way.

“On each floor we can breed 1,270 pigs,” says Yuanfei Gao, vice-president of Yangxiang, the company that built the farm. “But in the future with the design of the new buildings we plan to have 1,300 pigs per floor.”

Yangxiang is one of the Chinese giants of the pork industry, producing about 2 million pigs a year in a dozen farms throughout China. The Yaji mountain site is its largest and most advanced multistorey farming system, and will have the capacity to produce around 840,000 pigs a year when construction is finished.