Role of fibre in rabbit diets. A review

Abstract

The effect of fibre on rate of passage, control of gut flora, caecal fermentation, and performance of rabbits has been reviewed. Both physical and chemical characteristics of fibre affect these variables. An increase of the proportion of fine particles (< 0.315 mm) increases NDF digestibility, acidity and weight of caecal contents, fermentation time and microbial protein recycled through caecotrophy, but decreases rate of passage and intake. A minimal proportion of large particles (> 1.25 mm) is also required to allow an adequate turnover rate of caecal contents, and then to maximise microbial efficiency. The fraction of pectin components (arabinose, galactose and uronic acids) of cell walls accounts for most of the total fibre digestibility. An increase in the dietary concentration of these constituents leads to an increase of acidity of caecal contents and microbial protein recycled through caecotrophy. Dietary lignin content is negatively related to energy digestibility and also to the accumulation of digesta in the caecum. Both excessive and insufficient dietary fibre levels lead to an impairment of rabbit's performance. Practical recommendations on optimal fibre concentrations and minimal proportion of large particles are given for breeding does, fattening rabbits and mixed diets. © Elsevier / Inra.