EFFECTS OF DIETARY FIBER AND ON INTESTINAL GROWTH, CELL-PROLIFERATION, MORPHOLOGY IN GROWING PIGS

Growing pigs (initial BW 14.3 +/- 1.2 kg) were fed isocaloric (3.26 Mc al of ME/kg) and isonitrogenous (16% CP) diets containing either 0 (lo w fiber, LF; n = 4) or 10% (high fiber, KF; n = 4) wheat straw for ad libitum intake for 14 d. On d 14, each pig was injected i.v. with brom odeoxyuridine (BrdU, a thymidine analog; 5 mg/kg) arid was slaughtered 1 h later. Visceral organs (liver, pancreas, and intestines) were wei ghed, and tissue samples were obtained. Feed consumption, daily gain, gain: feed, and final BW did not differ between treatments. Neither vi sceral weights nor visceral weights per unit of eviscerated BW were af fected by diets. Tissue concentrations of DNA (milligrams/gram of tiss ue) were lower (P < .03) in HF than in LF only for jejunum, ileum, and liver. Contents of DNA and protein (milligrams) did not differ betwee n LF and HF for intestinal segments or liver. Content of RNA (milligra ms) was greater (P < .04) in HF than in LF only for colon. The number of crypt cell nuclei that were labeled with BrdU (indicating DNA synth esis and thus cell proliferation) was increased (P < .03) in HF relati ve to LF for jejunum and colon. The number of epithelial cells exhibit ing DNA fragmentation (indicating programmed cell death) was greater ( P < .07) in the HF than in the LF group for jejunum and ileum. Width o f intestinal villi was increased(P < .10) in HF vs LF for jejunum and ileum. Depth of intestinal crypts was increased (P < .08) in HF vs LF for jejunum, ileum, and colon. Thus, high dietary fiber alters the rat e of intestinal cell turnover as well as intestinal morphology in grow ing pigs.