Influence of dietary beet pulp on caecal VFA, experimental colibacillosis and iota-enterotoxaemia in rabbits

A total of 120 rabbits, weaned at 28 days of age (mean weight 610 g), were fed one of two iso-energetic (10.2 MJ ADE kg−1) and iso-proteic (175 g kg−1) diets ad libitum. The diets differed in the main fibre source; 240 g kg−1 beet pulp was incorporated in diet P and 54 g kg−1 flaxchaff and 300 g kg−1 alfalfa meal in diet F. As a result, diets P and F contained 142 and 163 g kg−1 crude fibre, 102 and 138 g kg−1 indigestible fibre, 343 and 311 g kg−1 neutral detergent fibre (NDF), 170 and 181 g kg−1 acid detergent fibre (ADF) and 46 and 66 g kg−1 acid detergent lignin (ADL), respectively. Rabbits were inoculated orally withClostridium spiroforme strain NCTC 11493 and/or a moderately enteropathogenicEscherichia coli (EPEC) strain belonging to sero/biotype O132/2+. Each litter was proportionally divided over the eight experimental groups. Administration of diet P was followed by a significant 30% increase of caecal weight and a 22% increase in total volatile fatty acid (VFA) production, whereas caecal pH decreased by 0.27 units in comparison with diet F. NH3 levels were unaffected. Neither diet significantly favoured proliferation of saprophytic faecalEscherichia coli. No significant influence was established either on faecalEscherichia coli numbers nor on mortality (30%) after experimental infection with EPEC. Clinical signs were less pronounced in rabbits fed diet P with less diarrhoea and significantly better weight gain in surviving rabbits (+28%). However, the same diet P promoted iota-enterotoxaemia with reduced weight gain (−29%) and impaired feed conversion (+40%). FaecalC. spiroforme scores remained elevated during 24 days post-infection, two out of ten rabbits died of enterotoxaemia and two more rabbits showed liquid diarrhoea. Experimental infection of rabbits fed diet F caused only a 2 day increase of faecalC. spiroforme scores without clinical signs.