Pilot study of innovative silage effects on pig gastrointestinal microbiota

The aim of this study was to evaluate whether dietary supplementation with an innovative silage (IS) created using 60% olive mill waste, 20% grape pomace and 20% deproteinised feta cheese waste solids) can modulate the composition of the ileal and caecal microbiota in weaned (Exp.1) and finishing (Exp.2) pigs. In Exp.1 (40-day supplementation), forty- five crossbred weaned pigs were randomly assigned to the 0% (Control), 5% or 10% IS groups (15 replicates/experimental diet). In Exp.2 (60-day supplementation), eighteen finishing pigs from Exp.1 were fed the control diet for 8 weeks before being re-assigned to their original experimental groups and diets of 0% (Control), 5% or 10% IS (6 replicates/experimental diet). Performance parameters were recorded and ileal and caecal digesta and mucosa were collected at the end of each experiment, from 5 pigs per experimental diet in Exp.1 and 6 pigs per experimental diet in Exp.2 for microbiota analysis using 16S rRNA gene sequencing. No significant effects on performance parameters were observed. In Exp.1, 5% IS supplementation increased the relative abundance of Prevotellaceae family, Coprococcus genus and Alloprevotella rava (OTU_48) and reduced the relative abundance of Lactobacillus genus in the caecum compared to the control and 10% IS diets (p<0.05). In Exp.2, 5% IS supplementation led to compositionally more diverse and different the ileal and caecal microbiota compared to the 0% control group (p<0.05; p=0.066 for ß- diversity in ileum). Supplementation with the 5% IS increased the relative abundance of Clostridium celatum/disporicum/saudiense (OTU_3) in the ileum and caecum and Bifidobacterium pseudolongum (OTU_17) in the caecum and reduced the relative abundance of Streptococcus gallolyticus/alactolyticus (OTU_2) compared to the control diet (p<0.05). Similar effects on C. celatum/disporicum/saudiense and S. gallolyticus/alactolyticus were observed with the 10% IS diet in the caecum (p<0.05). IS has the potential to beneficially alter the composition of the gastrointestinal microbiota in pigs.