Some Properties of the Nonsporing Anaerobes from Poultry Caeca

MANY DIFFERENT types of anaerobic nonsporing bacteria are known to occur as a major part of the caecal flora of birds. In this laboratory they have been isolated from chickens, turkeys, pheasants and ducks at c. lOl'J/g of wet caecal material. Very little is known about the function of the caecum and the role of the caecal flora in the nutrition of the bird. The involvement of the caecum in the digestion of the crude fibre complex (lignin, pentosans, hemicelluloses and celluloses) in the domestic fowl has been considered by Thornburn & Willcox (1965) but their results were inconclusive. Masson (1954) compared diets containing different types of starch. She found by microscopical examination that a significant quantity of potato starch reached the caecum but that cereal starches tended to be digested higher up the gut. The appearance of the caecal flora in the 2 cases was markedly different. Using a radiographic technique, Akester, Anderson, Hill & Osbaldiston (1967) found that urine will flow back into the caecum but not into the small intestine. It is thus probable that uric acid, the main nitrogenous excretory substance of the bird, is present in caeca. The anaerobic bacteria so far isolated from caeca have now been examined for their ability to attack various substrates of potential importance and the results are given in this paper. In the report of the Joint Committee on the Use of Antibiotics in Animal Husbandry and Veterinary Medicine (REPORT, 1969) it was recommended that therapeutically important antibiotics such as the tetracyclines and penicillins should be withdrawn from use as animal feed supplements. Whilst testing the anaerobes on a number of substrates the opportunity was also taken to test their resistance to zinc bacitracin and virginiamycin, antibiotics which are used at present as poultry feed supplements. At the present time the isolation and characterization of the caecal anaerobes is laborious. The behaviour of the individual organisms on a number of substrates has been used in an attempt to develop certain selective and differential media combining