In Exp. 1, 80 growing pigs (27.1±0.7 kg) were used in a 42-d experiment to evaluate the effect of levan-type fructan on growth performance, digestibility, blood profile, and fecal microbiota. Pigs were randomly allocated to 1 of 4 treatments, according to initial BW and gender, with 5 replicate pens per treatment and 2 barrows and 2 gilts per pen. Treatments were corn-soybean meal-based diets supplemented with 0%, 0.05%, 0.10%, or 0.20% levan-type fructan. Average daily gain and G:F increased (quadratic, P<0.05), as dietary levan-type fructan increased from 0 to 0.2%. Similarly, the apparent total tract digestibility of N and GE increased (quadratic, P<0.05), as dietary supplementation of levan-type fructan increased. Dietary levan-type fructan supplementation increased fecal Lactobacillus counts linearly (P<0.05). In Exp. 2, 20 individually housed barrows (26.2±0.6 kg) were used to evaluate immune responses after an Escherichia coli lipopolysaccharide (LPS) challenge. Pigs were fed corn-soybean meal-based diets supplemented with 0% or 0.10% levan-type fructan for 42 d. At d 42, 5 pigs from each treatment were injected with E. coli LPS (0.01% of BW) and the other 5 pigs with sterile saline solution, resulting in a 2×2 factorial arrangement of treatments. Blood was taken 0, 2, 4, 6, and 8 h after challenge. Challenge with LPS decreased blood lymphocyte percentage and had an interactive effect with levan-type fructan inclusion at 4, 6, and 8 h (P<0.01). Levan-type fructan supplementation increased (P<0.05) white blood cells at 6 and 8 h, and increased (P<0.05) lymphocyte percentage at 8 h after the challenge. Lipopolysaccharide injection increased (P<0.05) rectal temperature at 2 and 4 h, and had an interactive effect (P<0.05) with levan-type fructan supplementation at 4 h after the challenge. At 2, 4, 6, and 8 h, serum cortisol, tumor necrosis factor-α, and IL-6 concentration increased (P<0.05) by LPS challenge, and there was an interactive effect between LPS challenge and the inclusion of levan-type fructan (P<0.05). Dietary levan-type fructan supplementation decreased serum cortisol concentration at 8 h, tumor necrosis factor-α concentration at 4, 6, and 8 h, and IL-6 concentration at 6 and 8 h after the challenge (P<0.05). In conclusion, dietary supplementation with 0.10% levan-type fructan can improve growth performance, digestibility, and fecal Lactobacillus counts, and has a beneficial effect on the immune response during an inflammatory challenge in growing pigs.
