Fermentation patterns in rabbit caecal cultures supplied with plant polysaccharides and lactate

Abstract

Fermentation patterns were investigated in anaerobic cultures of the rabbit caecal contents supplied with starch, hemicellulose, pectin, inulin and sodium lactate. Pectin and inulin were fermented more rapidly than starch and hemicellulose. Fermentation of pectin produced the highest amount of fermentation gas. The highest molar proportion of acetate was found in volatile fatty acids (VFA) of cultures supplied with pectin or without substrate. The highest molar proportions of propionate, butyrate and caproate were found in cultures supplied with inulin, sodium lactate and starch, respectively. Acetate and butyrate accounted for 68 - 85 % of metabolite carbon. Low proportions of propionate and valerate were specific for all substrates. The production of methane was roughly proportional to the VFA production (one mol of methane per 5.9 - 7.3 mols of VFA). Hydrogen recovery values varied from 50.5 to 61.0 %, suggesting the presence of H2- dependent acetogenesis.