COMBINING TWO PROBIOTIC STRAINS WITH OLIGOFRUCTOSE AND INULINE ABOLISHES THEIR BENEFITS AGAINST SALMONELLA IN PIGLETS

Background/Aims: The efficacy of two probiotic strains (Bifidobacterium longum subsp. infantis CECT 7210 (Laboratorios Ordesa S.L.) and Lactobacillus rhamnosus HN001) combined or not with a prebiotic mixture of oligofructose and inulin against Salmonella typhimurium was evaluated. Methods: A total of 96 piglets (28 days) were distributed into 32 pens assigned to 5 treatments: one non-challenge (CTR+) and four challenged: same diet (CTR-), or supplemented with probiotic (> 3x1010cfu/kg each, PRO), prebiotic (5%, PRE) or their combination (SYN). After one week, animals were inoculated with Salmonella. Feed intake, weight and clinical signs were recorded. On days 4 and 8 post-inoculation (PI), one animal per pen was euthanized and samples collected for Salmonella counts, fermentation products, ileal histomorphology and serum TNF-a and PigMAP analysis. Results: After the challenge, feed intake was decreased but more markedly in the SYN group that showed a lower final weight (Intake: 438a, 315b, 293b, 237b and 315b g/d, P< 0.001; Final BW: 10.4a, 9.3ab, 8.9ab, 8.2b and 9.4ab kg, P= 0.009; for CTR+, PRO, PRE, SYN and CTR-, respectively). PRE and SYN groups showed more liquid ileal consistency on day 8 PI (P= 0.009). A higher percentage of animals receiving PRO became negative to Salmonella in faeces at the end of the study (65% PRO vs 0 % CTR- (P= 0.03)). Lower amounts of ileal SCFA were observed in SYN (P= 0.025) and valerate was increased in PRE and SYN. At day 8PI a significant decrease in the ileal villous/crypts ratio was found in challenged groups except for PRO (1.06a CTR+, 0.96ab PRO, 0.84b PRE, 0.84b SYN, 0,85b CTR-). Conclusion: In conclusion, the combined probiotic strains were able to enhance the response of the animals against Salmonella with improved ileal histological architecture and a faster clear out of the pathogen from the gut. However, these beneficial effects disappeared when the probiotic was combined with the prebiotic mixture.