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

¹ USDA-ARS, National Swine Research and Information Center, Ames, IA, 50011-3310

^* To whom correspondence should be addressed. E-mail: weberte{at}nsric.ars.usda.gov.

	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 (S6K1) were also determined. Pigs (n = 120; initially 5.2 kg and 24 d of age) were randomly assigned to diets containing one of four different fiber sources. The dietary fiber treatments were: 1) control diet containing no added fiber source, 2) diet containing 7.5% distillers dried grains with solubles (DGGS), 3) diets containing 7.5% soybean hulls (SBH), or 4) diet containing 7.5% citrus pulp. The experimental diets were fed for 4 wk in two 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, 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 DGGS had a greater (P < 0.05) relative abundance of the mRNAs encoding IL-6, IL-1, and IL-10 in ileum tissue than pigs fed all other diets. Pigs consuming diets containing DGGS had no effect on the relative abundance of tumor necrosis factor or interferon- mRNAs 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 S6K1 in jejunum, ileum, or colon tissue on d 7. These results indicate that feeding 7.5% of a fiber source as DGGS, SBH, or citrus pulp does not affect growth performance or circulating markers of inflammation in weanling pigs, and that feeding DGGS increases the expression of both proinflammatory and anti-inflammatory cytokines in intestinal tissue.

Key Words: cytokines, fiber, nursery diets, pigs