Vietnamese Pot-bellied is the exonym for the Lon I (Vietnamese: Lợn Ỉ) or I pig, an endangered traditional Vietnamese breed of small domestic pig.
The I is uniformly black and has short legs and a low-hanging belly, from which the name derives. The I is reared for meat. It is slow-growing, but the meat has good flavour. Then I was depicted in the traditional Đông Hồ paintings of Bắc Ninh province as a symbol of happiness, satiety and wealth.
The I is a traditional Vietnamese breed. It is thought to have originated in the Nam Định province of Vietnam, in the Red River Delta. It was the dominant local pig breed in most provinces of the delta and was widely distributed in Nam Định province and the neighbouring provinces of Hà Nam, Ninh Bình and Thái Bình, as well as in the province of Thanh Hóa immediately to the south, in the North Central Coast region.
Until the 1970s the I was probably the most numerous pig breed in northern Vietnam, with numbers running into millions. From that time, the more productive Móng Cái began to supplant it. The National Institute of Animal Husbandry of Vietnam started a conservation programme, with subsidies for farmers who reared purebred stock, but this had the little benefit – there was some increase in numbers but at the cost of increased inbreeding. In 1991, the total population of the I was estimated at 675 000, and by 2010 the estimated number was 120. In 2003 the National Institute of Animal Husbandry listed its conservation status as “critical”; in 2007 the FAO listed it as “endangered”.
Small numbers of I pigs were exported in the 1960s to Canada and Sweden, to be kept in zoos or to be used for laboratory experiments. Within a decade, the I had spread to animal parks in other countries in Europe; a few were reared on smallholdings. I entered the United States from Canada in the mid-1980s, and by the end of the decade, the “pot-bellied pig” was being marketed as a pet. Not all of these were purebred, and some grew to considerable size; the fad was short-lived.
In 2013 it was declared an invasive species in Spain.