الكاتب: Multiple References

In common with other species, the alimentary tract of the porcine foetus is sterile until birth (Fuller 1962; Gordon and Pesti 1971). Thereafter contact with the sow and the environment leads to successional colonisation by a variety of microbes (Smith 1965; Contrepois and Gouet 1973). This establishment of bacterial activity is regarded as complementary to the digestive functions of the host by extending the range of digestive enzymes and, under normal conditions, providing a barrier against invading pathogens. For instance, dosing newly hatched chicks with faeces from adult birds prevented salmonellas from colonising the caecae (Nurmi and Rantala 1973). In contrast, germ-free mice or animals dosed with large amounts of antibiotics show enhanced susceptibility to salmonella infection compared with conventional rodents (Bohnhoff et a1 1954; Collins and Carter 1978).