ASSESSMENT OF THE ACTIVITY OF A FRUCTO-OLIGOSACCHARIDE ON DIFFERENT CECAL PARAMETERS IN RABBITS EXPERIMENTALLY INFECTED WITH ESCHERICHIA-COLI 0.103

Thirty 51-d-old rabbits, fed since the 18th d on a mixed diet containing a fructo-oligo-saccharide (FOS) added at 0.25% (FOS group) and 30 51-d-old rabbits without FOS (C group) were infected via oesophagal routs, with 2 x 10(7) E coli O.103 strain B-10. Seven d after challenge the first digestive symptoms were observed, and 20% of the animals died in each group; in the survivors, the number of rabbits without any clinical signs was significantly higher in the FOS group (35.7% versus 14.8% in the C group P < 0.05). In the FOS group the body weights of survivors were 95 g more than the controls weights (2 454 g versus 2 359 g). At 80 d, 14 animals were euthanised in each group and different caecal parameters were compared. In the FOS group the following were observed: a lower pH: 6.04 versus 6.26 (P < 0.05); a strong rise in total VFA: 73.4 mmol/kg versus 56.2 mmol/kg (P < 0.05); a marked decrease of NH3: 11.1 Mmol/kg versus 17.0 mmol/kg (P < 0.001); an increase in saprophytic E coli counts: 10(4.2)/g versus 10(2.5)/g (P < 0.001). The results confirm the possibility that FOS increases the rate of VFA production in the caecum. With this increase is associated a higher E coli population (P < 0.001), characteristic of a favourable biochemical environment (pH, VFA, NH3) and considered by the authors as able to reduce the morbidity (but not the mortality) induced by an enteropathogenic E coli infection.