Effects of adding fibrous feedstuffs to the diet of young pigs on growth performance, intestinal cytokines, and circulating acute-phase proteins

Abstract

The effects of feeding different types of fiber to weanling pigs on growth performance, intestinal and liver cytokine expression, circulating acute-phase proteins, and IGF-I were evaluated. Intestinal tissue abundance of DNA, protein, and phosphorylated S6 kinase were also determined. Pigs (n = 120; initially 5.2 kg and 24 d of age) were randomly assigned to diets containing 1 of 4 fiber sources: 1) control diets containing no added fiber source, 2) diets containing 7.5% distillers dried grains with solubles (DDGS), 3) diets containing 7.5% soybean hulls, or 4) diets containing 7.5% citrus pulp. The experimental diets were fed for 4 wk in 2 phases (phase 1, wk 1 and 2; phase 2, wk 3 and 4). Intestinal tissue samples, liver samples, and blood samples were collected from a subset (n = 24; 6 pigs/treatment) of the pigs on d 7, and blood samples were collected from another subset (n = 24; 6 pigs/ treatment) of pigs on d 28 of the experiment. Dietary treatment had no effect on ADG, ADFI, or G:F throughout the experiment. Likewise, pig BW variability (CV), plasma IGF-I, or the plasma concentration of the acute-phase proteins, alpha(1)-acid glycoprotein, C-reactive protein, and haptoglobin, were not affected by dietary treatment. Real-time RT-PCR analysis revealed that on d 7, pigs fed DDGS had a greater (P < 0.05) relative abundance of the mRNA encoding IL-6, IL-1beta, and IL-10 in ileum tissue than pigs fed all other diets. Diets containing DDGS had no effect on the relative abundance of tumor necrosis factor alpha or interferon-gamma mRNA in ileum tissue on d 7. The d-7 mRNA expression of cytokines was not altered in jejunum, colon, or liver tissue by dietary treatment. Intestinal tissue protein content or jejunum and ileum DNA concentrations were not affected by diet. Western blot analysis found no effect of dietary treatment on the activation of S6 kinase in jejunum, ileum, or colon tissue on d 7. These results indicate that feeding 7.5% of a fiber source as DDGS, soybean hulls, or citrus pulp does not affect growth performance or circulating markers of inflammation in weanling pigs and that feeding DDGS increases the expression of both proinflammatory and antiinflammatory cytokines in intestinal tissue.