1, coagulation: the cut part is a blood clot formed by pig blood coagulation, which is a normal coagulation reaction. In this case, black is the color of blood after coagulation.
2. Disease or infection: Black is tissue necrosis caused by disease or infection, such as foot-and-mouth disease virus infection, oral ulcer and other diseases can lead to oral tissue injury and necrosis.
3. Tumor or sarcoma: Black is caused by tumor or sarcoma in pigs, which will affect the health of oral tissues and lead to blackening of local tissues. The pig's arch refers to the pig's mouth, including the pig's lips, oral mucosa, teeth and related tissue structures. Pigs eat and chew food with arch mouth, which is one of the key parts for pigs to eat.