Pigs have the habit of living in groups and like to live in groups, which strengthens their imitation reflex. Piglets who can't eat feed follow pigs who can eat feed. At the same time, the mutual promotion of groups is also obvious. For example, feeding pigs in groups eats faster, eats more and gains more weight than feeding pigs alone. Therefore, pigs should be fed in groups, not individually. In the herd, it is not appropriate to have a large difference in individual weight, and it is not appropriate to mix different breeds of pigs for intra-herd management, so as to avoid uneven feeding or uneven feeding, resulting in irregular growth and development. When a strange pig enters another group, this pig becomes the target of the whole group of pigs. Attacks are usually serious, ranging from injury to death. The fighting behavior of pigs is mostly influenced by the feeding density. When the density of pigs is too high and the space occupied by each pig decreases, the number and intensity of intra-group fights increase, thus affecting the feed intake and weight gain. The newly gregarious pigs are mainly fighting for gregarious ranking.

In people's traditional thinking, pigs are "soil". That was not the case. Pigs are the cleanest animals of all domestic animals. Usually keep the sleeping nest clean and dry to avoid being polluted by feces and urine. Pigs defecate somewhere and never defecate where they eat and sleep. Pigs often choose a corner to excrete in a spacious pen and excrete in a low humidity place near the water source.

(2) The nutritional requirements of pigs vary with genotype, feeding environment and physiological stage. In the production process, the nutritional requirements of pigs can be divided into piglets, growing pigs (including growing-finishing pigs and reserve pigs), sows (including empty pregnant sows, pregnant sows and lactating sows) and boars.