Effect of low dose of fumonisins on pig health: immune status, intestinal microbiota and sensitivity to Salmonella

Abstract

The objective of this study was to measure the effects of chronic exposure to fumonisins via the ingestion of feed containing naturally contaminated corn in growing pigs infected or not with Salmonella spp. This exposure to a moderate dietary concentration of fumonisins (11.8 ppm) was sufficient to induce a biological effect in pigs (Sa/So ratio), but no mortality or pathology was observed over 63 days of exposure. No mortality or related clinical signs, even in cases of inoculation with Salmonella (5 × 10⁴ CFU), were observed either. Fumonisins, at these concentrations, did not affect the ability of lymphocytes to proliferate in the presence of mitogens, but after seven days post-inoculation they led to inhibition of the ability of specific Salmonella lymphocytes to proliferate following exposure to a specific Salmonella antigen. However, the ingestion of fumonisins had no impact on Salmonella translocation or seroconversion in inoculated pigs. The inoculation of Salmonella did not affect faecal microbiota profiles, but exposure to moderate concentrations of fumonisins transiently affected the digestive microbiota balance. In cases of co-infection with fumonisins and Salmonella, the microbiota profiles were rapidly and clearly modified as early as 48 h post-Salmonella inoculation. Therefore under these experimental conditions, exposure to an average concentration of fumonisins in naturally contaminated feed had no effect on pig health but did affect the digestive microbiota balance, with Salmonella exposure amplifying this phenomenon.

Figure 1

Changes over time in the proliferation capacity of lymphocytes in the presence of a Salmonella-specific antigen in pigs fed a diet containing fumonisins F(+) or not F(−) and inoculated with Salmonella S(+) or not S(−). Data (means ± SEM, n = 12 then n = 8 after D + 2) were statistically analyzed for each date using variance analysis (ANOVA) followed by the Tuckey test. The small letters (“a” and “b”) indicate a significant difference (p < 0.05).

Figure 2

Changes over time in the similarity between the profile of the faecal microbiota of the control group F(−)S(−) and those of the other groups of pigs: F(+)S(−), F(−)S(+) and F(+)S(+).

Figure 3

Diagram representing the main information in the experimental design according to the age of the pigs: weaning of all piglets, beginning of distribution of fumonisin-contaminated feed to the F(+) pigs at D − 7, Salmonella inoculation of the S(+) pigs at D0, first and second pig sacrifice dates at D + 2 and D + 56, respectively.