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

Abstract

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 with Clostridium spiroforme strain NCTC 11493 and/or a moderately enteropathogenic Escherichia 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. NH 3 levels were unaffected. Neither diet significantly favoured proliferation of saprophytic faecal Escherichia coli. No significant influence was established either on faecal Escherichia 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%). Faecal C. 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 faecal C. spiroforme scores without clinical signs.