Many foodborne microorganisms are present in healthy animals raised for food, usually in their intestines, hides, feathers, etc. Meat and poultry carcasses can be contaminated during slaughter by contact with small amounts of intestinal contents. For example, in animals slaughtered in rural communities without any safety measures, microorganisms present in the animals' intestines can easily contaminate the meat.
Animal hides are an important source of contamination of the general environment, the hands of meat workers, and skinned meat carcasses. Hides are a primary source of E.coli O157:H7 and Salmonella species, both of which cause sickness and diarrhoea. Hides become contaminated either because the outside of the hide is dirty, or because once removed from the animal, the inside of the hide is a good breeding place for microorganisms.