Bacterial microbiome in colon and faeces of weaned piglets in dependence of varying phosphorus levels in the diet

Phosphorus is an element with potential impact on the intestinal microbiota of pigs. Studies revealed that bacterial growth was limited in the intestine feeding low concentrations of phosphorus and that ileal bacteria increased with higher calcium and phosphorus feed contents, whereas there was no effect on bacterial numbers in the colon. Therefore, the aim of this study was to evaluate the influence of varying phosphorus levels in diets of piglets on the bacterial microbiome in colon chyme and faeces.

Weaned piglets (n=18) were divided into 3 groups (n = 6) fed a pelleted diet (on the basis of wheat, barley and soybean; supplied with varying levels of monocalcium phosphate) with soluble phosphorus contents of 0.32% (Low-P), 0.54% (Normal-P) and 0.74% (High-P) of dry matter. On day 35 (d35) samples were taken from each piglet before slaughtering (faeces) and after slaughtering (intestinal chyme). Bacterial DNA was isolated and amplificated via polymerase chain reaction. Afterwards, a denaturing gradient gel electrophoresis (DGGE) was performed and sequencing was conducted by Eurofins (Ebersberg, Germany). Sequences were compared with the database of the National Center for Biotechnology Information using the Basic Local Alignment Search Tool. The DGGE band patterns were analyzed with Bionumerics 5.0 (Applied Maths, Inc., Sint-Martens-Latem, Belgium).

Dietary P-level neither affected DGGE band patterns nor the appearance of species in the different diet samples. Less than 60% similarities between band patterns of repeated trials were found, whereby band patterns of colonic and faecal samples of each experiment showed similarities of up to 80%. Dominating species in colonic and faecal samples were Roseburia faecis, Eubacterium cellulosolvens, Sarcina ventriculi and Butyrivibrio fibrisolvens, which are involved in the bacterial degradation of indigestive polysaccharides (except Sarcina ventriculi). Facultative pathogens (e. g. Streptococcus gallolyticus) were rarely detected and could not be identified in Low-P. Lactobacillus spp. was documented in colonic and faecal samples of solely one piglet.

Using DGGE, no clear effect of the dietary P-level on the colonic and faecal bacterial microbiome was detected and there was no apparent effect of the diets on the occurrence of species or DGGE band patterns. Assuming that there is no significant impact on the intestinal microbiome a Preduction in swine nutrition might be feasible without negative effects on the intestinal health.

Disclosure of Interest: None Declared.