The potential of neokestose as a prebiotic for broiler chickens

[摘要] English: The inulin neoseries, trisaccharide, neokestose was produced by the yeast Xanthophyllomyces dendrorhous (Phaffia rhodozyma Y4-3) during growth on sucrose. To produce neokestose, whole cells harvested from the late exponential growth phase were incubated for 36 to 40 h at 25 oC in 0.2 M citratephosphate buffer (pH 7) containing 220 g.l-1 sucrose. Neokestose made up about 50 % of this mixture, which was purified equally well by both a carbon:celite chromatography as well as a batch filtration process, when eluting with similar amounts of water followed by a 50 % ethanol elution step. A final product was combined from various purification runs which consisted of 82.6 % neokestose, 8.7 % sucrose, 7.6 % GF3, 1.2 % glucose and 0.1 % fructose. Lactobacillus and Bifidobacterium genera are considered part of the beneficial group in in the intestine of animal and man. Bifidobacterium levels were higher than Lactobacillus levels in the caeca of New Hampshire layers, whereas in this study only Lactobacillus species were found in broilers. The reason for the absence of the Bifidobacterium species in the caecum of broilers was not determined. The prebiotic effect was evaluated on 5 week old broiler caecal material in vitro over 24 hours based on the viable levels of the total anaerobic bacteria, Lactobacillus and coliforms. The prebiotic effect was also evaluated on viable levels of added Salmonella Typhi, Escherichia coli and Campylobacter jejuni. Volatile fatty acids and pH were measured. The effect of neokestose on these groups was compared to that of inulin, a known prebiotic, and glucose. The total anaerobe and Lactobacillus levels increased over 24 hours for neokestose, inulin and glucose. Although there was no significant difference between the treatments higher levels were found for neokestose and glucose than for inulin. A decrease in the viable levels of E. coli, S. Typhi and C. jejuni were seen over 24 hours. The production of acetic acid, butyric acid and propionic acid was not significantly different for the treatments and the control. The pH decrease over 24 hours for the treatments was significantly different from the control, which indicated that lactate (not measured) production was probably higher in the neokestose, inulin and glucose treatments. In vivo tests are, however, required to fully evaluate the prebiotic and 'bifidogenic effect of neokestose for broilers.

[发布机构] University of the Free State