At present, substantial amounts of low-cost, fibrous co-products are incorporated into pig diets to reduce the cost of raising swine. However, diets that are rich in fiber are of low nutritive value because pigs cannot degrade dietary fiber. In addition, high-fiber diets have been associated with reduced nutrient utilization and pig performance. However, recent reports are often contradictory and the negative effects of high-fiber diets are influenced by the fiber source, type, and inclusion level. In addition, the effects of dietary fiber on pig growth and physiological responses are often confounded by the many analytical methods that are used to measure dietary fiber and its components. Several strategies have been employed to ameliorate the negative effects associated with the ingestion of high-fiber diets in pigs and to improve the nutritive value of such diets. Exogenous fiber-degrading enzymes are widely used to improve nutrient utilization and pig performance. However, the results of research reports have not been consistent and there is a need to elucidate the mode of action of exogenous enzymes on the metabolic and physiological responses in pigs that are fed high-fiber diets. On the other hand, dietary fiber is increasingly used as a means of promoting pig gut health and gestating sow welfare. In this review, dietary fiber and its effects on pig nutrition, gut physiology, and sow welfare are discussed. In addition, areas that need further research are suggested to gain more insight into dietary fiber and into the use of exogenous enzymes to improve the utilization of high-fiber diets by pigs

The effects of adding a multienzyme complex to a diet containing distillers dried grains with solubles (DDGS) produced from a 1:1 mixture of corn and wheat on visceral organ weight, intestinal morphology, and fasting whole-body oxygen consumption (FWBOC) were investigated in growing pigs in a 28-d trial. Twenty-four pigs (BW = 19.9 ± 0.5 kg) were individually housed in floor pens and randomly assigned to 3 experimental diets (8 pigs per diet). The diets contained corn and soybean meal with 0% (control) or 30% DDGS (DDGS diet); the third diet was supplemented with a multienzyme complex in addition to the 30% DDGS (DDGS + enzyme diet). All diets had similar nutrient concentrations and met the 1998 NRC nutrient requirements for growing pigs. Pigs were fed at 4% of their BW once daily. On d 15, 4 pigs from each dietary treatment were randomly selected for measurement of FWBOC during the 24- to 30-h postprandial period using an open-circuit indirect calorimeter. At the end of the study, pigs were killed to determine visceral organ weights, ileal and cecal digesta viscosity, and intestinal morphology. There was no effect (P > 0.05) of dietary treatment on final BW, WBFOC, or digesta viscosity. Empty BW of pigs fed the control diet was heavier (P = 0.02) than that of pigs fed the DDGS diet, but the empty BW of pigs fed the DDGS + enzyme diet was not different (P > 0.05) from that of pigs fed the control or DDGS diet. There were no differences (P > 0.05) in empty BW of liver, spleen, pancreas, heart, stomach, small intestine, and cecum among dietary treatments on a per kilogram basis. However, pigs fed the DDGS diet had heavier (P < 0.05) colon plus rectum and portal-drained viscera (PDV) than pigs fed the control diet, but weights of colon plus rectum and PDV in pigs fed the DDGS + enzyme diet were not different (P > 0.05) from those of pigs fed the control diet. Although morphological data showed no differences (P > 0.05) in the duodenum, jejunum, and colon segments among dietary treatments, the DDGS diet tended to decrease (P < 0.10) villous height and villous height to crypt depth in the ileum. The results of this experiment indicated that pigs fed a diet containing 30% DDGS have reduced dressing percentage and increased visceral organ mass compared with pigs fed a corn-soybean meal diet. However, the addition of a multienzyme complex to the DDGS diet resulted in pigs having a dressing percentage and visceral organ mass that are not different from those of pigs fed a corn-soybean meal diet. Copyright © 2012. American Society of Animal Science .

The present study evaluated supplemental carbohydrase effect on performance, intestinal nutrient uptake, and transporter mRNA expressions in growing pigs offered a high-fiber diet manufactured with distillers dried grains with solubles (DDGS). Twenty-four pigs (22.4 ± 0.7 kg BW) were randomly assigned to 1of 3 nutritionally adequate diets (8 pigs per diet) based on corn and soybean meal (SBM) with either 0 (control) or 30% DDGS (high fiber [HF]). The third diet was supplemented with a xylanase and β-glucanase blend (XB) in addition to the 30% DDGS (HF+XB). Parameters determined were ADFI, ADG, G:F, plasma glucose and plasma urea nitrogen (PUN) concentrations, jejunal tissue electrophysiological properties, and mRNA expressions of the sodium-dependent glucose transport 1 (SGLT1) and cationic AA transporter, b^o,+AT, in the jejunal and ileal tissues. In addition, mRNA expressions of the short-chain fatty acid transporters, monocarboxylate transporter 1 (MCT1) and sodium-coupled monocarboxylate transporter, and mucin genes were quantified in the ileum. Feed intake, plasma glucose, and jejunal tissue electrophysiological properties were not affected (P > 0.05) by diet. However, control-fed pigs had superior growth rate and feed efficiency and higher PUN (P < 0.05) than HF- and HF+XB-fed pigs. The HF diet increased (P < 0.05) SGLT1 mRNA expression in the jejunum and decreased (P < 0.05) b^o,+ mRNA expression in the ileum. The XB supplementation also increased b^o,+ mRNA expression in the ileum relative to HF-fed pigs. Additionally, MCT1 mRNA expression was greater (P < 0.05) in the ileum of the HF- and HF+XB-fed pigs. In the present study, XB supplementation influenced nutrient transporter mRNA expression, although it was not accompanied by improved pig performance.

The aim was to evaluate the effects of feeding resistant potato starch (RPS) as a natural source of resistant starch to weaned pigs for 28 d immediately after weaning. Sixty piglets (Yorkshire–Landrace × Duroc) weaned at 21 ± 2 d (1:1 male:female) with an initial BW of 7.2 ± 0.78 kg were assigned in a completely randomized design to 1 of 5 dietary treatments to give 6 observations per treatment and 2 pigs per pen. Dietary treatments consisted of a negative control corn–soybean meal–wheat–wheat middlings–based diet (NC; no antimicrobial agents added) or the NC supplemented with RPS either as powder or in capsules and each included at 0.5 or 1.0% as a top-dressing on each day. Diets were formulated to meet 1998 NRC specifications. Pigs were offered the experimental diets on an ad libitum basis for 28 d and water was available at all times. The ADG, ADFI, and G:F were determined weekly. Fecal score was determined daily for 14 d after weaning. At the conclusion of study, 1 pig from each pen was randomly selected and euthanized (n = 6 per treatment) to determine visceral organ weight, digesta pH, VFA, and ammonia N (NH₃–N) concentrations. Resistant potato starch supplementation improved (P < 0.001) fecal score, and pigs offered 1.0% RPS had more solid feces (P < 0.05) than those offered 0.5% RPS during the first 14 d after weaning, independent of the form of RPS. Resistant potato starch supplementation decreased (P < 0.05) ileal and cecal digesta pH regardless of the levels of RPS or mode of delivery. The total VFA concentrations in cecal digesta were greater (P < 0.05) but the molar proportion of branched-chain fatty acids were lower (P < 0.05) for pigs fed the RPS-containing diets compared with those fed the NC, irrespective of the RPS levels or the form of RPS. However, there were no differences (P > 0.10) in visceral organ weights, growth performance, and digestibilities of DM, CP, Ca, and P among treatments. The results of this experiment indicate that supplementing a weaner pig diet with at least 0.5% RPS independent of mode of delivery has the potential to enhance outcomes characteristic of a functional gut in weaned pigs without adverse effects on growth.

It was shown previously that high dietary fiber (DF) and immune system stimulation (ISS) with systemic Escherichia coli lipopolysaccharide independently increased the threonine (Thr) requirement to maximize growth performance and protein deposition (PD). However, no additive effects on the Thr requirement were observed when both DF and ISS were present. The objective of the present study was to investigate whether supplementing Thr to meet previously estimated requirements for high DF and systemic immune challenge would maintain performance of pigs exposed to an enteric immune challenge when fed high DF. A total of 128 pigs (22.6 ± SD = 1.6 kg initial BW) were assigned to 1 of 4 dietary treatments in a 2 × 2 factorial arrangement in a randomized complete block design (n = 8 pens/treatment and 4 pigs/pen) for 28 d. Treatments were a low-fiber (LF; 13% total DF) or high-fiber (HF; 20% total DF) diet with either a standard (STD; 0.65% SID) or supplemental (SUP; 0.78% SID) Thr level. After a 7-d adaptation, pigs were orally inoculated with 2 mL (2.3 × 10⁹ CFU/mL) of Salmonella typhimurium (ST). Blood samples and rectal swabs were obtained and rectal temperature recorded to determine clinical responses and ST shedding. On day 7 postinoculation, 1 pig/pen was euthanized and mesenteric lymph nodes, spleen, and digesta (ileum, cecum, and colon) were sampled to assess ST colonization and translocation. Body weight and feed intake were recorded on day 0, 7, and 21 postinoculation to calculate ADG, ADFI, and G:F. Rectal temperature increased (P < 0.05) 24 h postinoculation and remained elevated at day 6. Serum albumin concentration decreased (P < 0.05), whereas haptoglobin concentration increased (P < 0.05) postinoculation. There was no fiber or Thr effect (P > 0.05) on ST counts in the ileum and cecum, but a fiber × Thr interaction (P < 0.05) was observed in the colon. Supplemental Thr improved (P < 0.05) growth performance in LF- and HF-fed challenged pigs. However, performance of supplemented HF challenged pigs was less than (P < 0.05) supplemented LF challenged pigs. These results suggest that Thr supplemented to meet requirements for high DF and systemic immune challenge was not sufficient to maintain growth performance of pigs fed HF diets and challenged with an enteric pathogen.