Because the U.S. pig industry is very strictly regulated, basically large-scale and standardized pig farming, can be done half a month before the penning of the pig ban on leptin, to the penning of the time leptin has been metabolized in the pig body.

Additionally, leptin mainly remains in the liver of pigs, and Americans hardly eat food such as pig liver.

Leptin is used in the hog industry mainly as a supplemental part of the feed or as a feed additive, which is eaten by pigs to promote growth and reduce their body fat content. Its scientific name is clenbuterol hydrochloride, and because its core function is to improve the leanness of livestock animals such as pigs, cattle and sheep, it has a common name called lean meat essence.

China issued documents in 2001 and 2002 banning the use of beta agonist drugs as feed additives in food animals, and leptin belongs to this category.

The average domestic consumer knows about leptin from the 2011 leptin incident. With the use of leptin already banned in pig farming and other animal husbandry, there were a number of pig farms in Henan that were positive for leptin, and a number of feedstuffs containing leptin were also seized.

Leptin residues are high in the liver and other internal organs of pigs after its use. Influenced by dietary habits, Americans generally do not eat offal. Large-scale pig farming in the United States is very centralized, and pigs are usually sold as a whole batch which is easier to manage.

In the U.S., commercial hogs will stop feeding leptin half a month before they are farrowed so that the hogs can metabolize it themselves. Combined with spot checks by testing organizations, residues are kept within the human metabolism range.

Introduction of American Lai Hogs

Most American hogs contain ractopamine, a synthetic organic substance also known as "leptin". Ractopamine works to inhibit the growth of fat in animals, thereby promoting the growth of lean meat.

If a pig eats this kind of substance, its internal organs will absorb most of the ractopamine, and when a person eats this kind of pork containing a large amount of ractopamine, it will pose a threat to human health.

Reference for the above: Lai Pig - Baidu Encyclopedia