Single and combined effect of dietary Thyme (Thymus vulgaris) and Spirulina (Arthrospira platensis) on bacterial community in the caecum and caecal fermentation of rabbits

The objective of this study was to evaluate the effect of supplementation of the growing rabbits’ diet by Spirulina or/and Thyme (food supplement) on the composition and amount of the microbiota and production of volatile fatty acids of the rabbits’ caecum. We used classical culturing methods and after bacterial DNA extraction, the quantity of bacteria (belonging to phylum Firmicutes and Bacteroidetes) were determined by qPCR reactions with the aid of bacterial ribosome coding DNA at the Molecular Biology Laboratory, University of Kaposvár. The experiment was carried out using rabbits (Pannon White) from rabbit-farm of Kaposvar University. Young rabbits were weaned on the 35th day after birth. All experimental animals were the same age. Duration of Spirulina and/or Thyme supplementation –after weaning- was 48 days. Samples were collected on the 14th, 28th and 48th day of the supplementation. No dietary effect on pH of the caecal content was detected. The number of Escherichia coli, total anaerobic and strictly anaerobic bacteria decreased by age, no effect of the diet could be demonstrated. Supplementation with Thyme resulted in slightly higher ratio of propionic acid, but the difference was not significant. In conclusion, Spirulina and/or Thyme supplementation of diet after weaning had no substantial effect on the volatile fatty acid (VFA) production, while the classical microbiological determination did not find a substantial effect on the composition of the caecal microbiota. By the Quantitative PCR method we measured significantly lower bacterial copy numbers in the samples of ST treated group. This indicates that the ST (Spirulina 5% and 3% Thyme) feed supplementation has an antimicrobial effect on the investigated bacterial groups in the caecum of growing rabbit.