"Grass-mud pig" refers to a type of ecological pig raised in a grassland and mud-pond environment.

Grass-mud pig generally does not refer to any formally registered pig breed, but is a colloquial name for a pig-farming method that stays close to nature and for the pigs it produces. These pigs live in a muddy environment with green grass where they can root in the soil and roll around, and they are raised under free-range or semi-free-range systems. Their daily activity level is high, and they can regularly come into contact with soil and pasture grass, which is how the name "grass-mud pig" came about. Compared with fattening pigs kept confined in pens the whole time, the two differ noticeably in rearing method and activity status.

Because they exercise sufficiently and eat a varied diet, grass-mud pigs usually have a relatively sturdy constitution, and their coat color and body size vary with the breed being raised. Mud ponds help pigs cool down, protect the skin and reduce mosquito bites, while rooting in the soil for food is also a natural pig behavior, which can reduce the stereotyped behaviors commonly seen in confined environments, and animal welfare is often better. Correspondingly, this rearing method has a slower growth rate, and the marketing cycle is generally longer than that of ordinary confined pigs.

A common practice is to use orchards, understory areas or sloping land to fence off an activity area, lay down straw, rice husks and other bedding, and set up a mud-bathing area and supplementary feeding points, with the daily diet based mainly on conventional feed combined with green fodder. During rearing, vaccination and internal and external deworming still need to be carried out according to schedule, and the bedding should be turned over, replaced or replenished regularly to prevent the breeding of parasites and pathogens. The site should be far from water source protection areas, and manure and bedding should be composted and fermented before being returned to the fields for use, forming a crop-livestock cycle.

Grass-mud pork tends to be firmer in texture and is often positioned and sold as ecological pork or high-quality pork, but market names vary, so when purchasing, pay attention to the description of the rearing method and the quarantine certificate. For farmers, this model occupies a lot of land and has relatively high management costs, so it is suitable for operators with free-range land who take a quality-differentiation route to try on a small scale, and it is not advisable to blindly follow the trend and expand production.