Fig 1.
Diet can have direct (1) and indirect (2 and 3) effects on helminth infection.
Direct effects include food with anthelmintic properties (e.g., secondary plant metabolites) that might reduce the likelihood of establishment or the fecundity and survival of worms within the host. Indirect effects include the modulation of the gut microbiota and immunity.
Table 1.
Composition of the different experimental dietary treatments.
(HF: high-fiber diet; HS: high-starch diet; SF: sainfoin pellets supplementation; CONT: control pellets supplementation).
Fig 2.
Changes in FEC over the 21 days of the experimental periods for horses fed high-fiber (green bars) and high-starch (yellow bars) diets and supplemented with sainfoin pellets (light colors) or control pellets (dark colors).
We report the median and the interquartile range. A mixed model ANOVA followed by Tukey’s multiple comparisons test show significant differences in the values presenting different superscript letters within each treatment (p < 0.05).
Table 2.
General linear mixed model exploring the effect of diet (HF vs HS) and supplementation (SF vs CONT) on two traits referring to helminth infection (fecal egg count and L3 motility) over the 21 day experimental period.
We report the fixed effects but the model also included the horse ID and the horse ID * experimental period as random effects. FEC were assessed four times during the experimental period therefore the model also included time as a repeated measurement. L3 motility was only measured at day 21 and modelled using a multinomial distribution. We report the degrees of freedom (df), F and p values.
Fig 3.
Percentage of immobile, moderately mobile and highly mobile L3 larvae hatched from eggs recovered at D21 from feces of horses fed high-fiber (HF) or high-starch (HS) diets, supplemented with sainfoin pellets (SF) or control pellets (CONT).
Larval motility differed between SF and CONT (p < 0.05), independently of the diets.
Fig 4.
Fecal bacterial richness (A: number of ASV; B: Chao 1 index) and α-diversity (C: Shannon index; D: Inverse Simpson index) at D21 in horses fed high-fiber diet (HF) or high starch diet (HS).
We report the median and the interquartile range. Asterisks indicate significant differences between groups (p < 0.01).
Fig 5.
Principal coordinates analysis (PCoA) at amplicon sequence variants level showing the β-diversity (Bray-Curtis distance) at D21 in horses fed fiber diets (HF) or high starch diets (HS).
Ellipses represent the 95% confidence intervals.
Fig 6.
LDA effect size (LEfSe) cladograms showing the taxa most differentially associated with high-fiber or high starch diet.
The circles represent, going from the inner to outer circle: phyla, class, order, family and genus. Green circles represent taxa overrepresented in HF-fed horses and yellow circles taxa overrepresented in HS-fed animals.
Fig 7.
LDA effect size (LEfSe) cladograms showing the taxa most differentially associated with control or sainfoin supplementation in each diet ((A) High-fiber or (B) High starch).
The circles represent, going from the inner to outer circle: phyla, class, order, family and genus. Pink circles represent taxa overrepresented in SF-fed horses within the HF-diet.
Fig 8.
Total anaerobic, cellulolytic, amylolytic and lactate utilizing bacteria concentrations at D21 in fecal samples of horses fed high fiber diets (HF) or high starch diets (HS).
We report median values and interquartile range.
Fig 9.
Changes in pH of fecal samples of horses fed high-fiber diets (HF) or high-starch diets (HS) from D0 to D21.
We report median values and interquartile range. Asterisks indicate significant differences between groups (p < 0.01 and p <0.001).
Fig 10.
Total volatile fatty acids (VFAs) concentration at D21 in fecal samples of horses fed high fiber diets (HF) or high starch diets (HS).
We report median values and interquartile range.
Fig 11.
Proportions of Acetate (A), Propionate (B), Iso-butyrate (C), Butyrate (D), Iso-valerate (E) and Valerate (F) at D21 in fecal samples of horses fed high fiber diets (HF) or high starch diets (HS).
We report median values and interquartile range.
Fig 12.
Lactate concentration at D21 in fecal samples of horses fed high fiber diets (HF) or high starch diets (HS).
We report median values and interquartile range.
Fig 13.
Procalcitonin concentration in serum (A), LPS concentration in plasma (B), hematocrit (C), acetate concentration in plasma (D) and fecal acetate concentration (E) at D21 of horses fed the four treatments (HF-CONT, HF-SF, HS-CONT, HS-SF).
We report median values and interquartile range.