[Screening of community malnutrition by homecare staff in Neuchâtel--Switzerland]. / Dépistage de la dénutrition communautaire par les services de soins à domicile à Neuchâtel.

Malnutrition is unidentified in about 60% of malnourished people until their hospital admission. The screening of malnutrition and the institution of a nutritional therapy at home may decrease the mortality and the arise of in-hospital complications. In collaboration with NOMAD (General homecare organ in Neuchâtel - Switzerland), a pilot study was performed in order to evaluate the incidence of the community malnutrition. 129 homecare customers of NOMAD, mostly >70 years old, were screened by a trained staff using a score tool (SRNS) based on 5 simple criteria 39,5% of them were malnourished or at risk of malnutrition. The relevance of SRNS assessments was confirmed by a nutritional dietician in 81,85% of cases, corresponding to 28% of the whole cohort. This incidence is comparable to other studies.

Expression of a plant-derived peptide harboring water-cleaning and antimicrobial activities.

Drinking water is currently a scarce world resource, the preparation of which requires complex treatments that include clarification of suspended particles and disinfection. Seed extracts of Moringa oleifera Lam., a tropical tree, have been proposed as an environment-friendly alternative, due to their traditional use for the clarification of drinking water. However, the precise nature of the active components of the extract and whether they may be produced in recombinant form are unknown. Here we show that recombinant or synthetic forms of a cationic seed polypeptide mediate efficient sedimentation of suspended mineral particles and bacteria. Unexpectedly, the polypeptide was also found to possesses a bactericidal activity capable of disinfecting heavily contaminated water. Furthermore, the polypeptide has been shown to efficiently kill several pathogenic bacteria, including antibiotic-resistant isolates of Staphylococcus, Streptococcus, and Legionella species. Thus, this polypeptide displays the unprecedented feature of combining water purification and disinfectant properties. Identification of an active principle derived from the seed extracts points to a range of potential for drinking water treatment or skin and mucosal disinfection in clinical settings.

Neutral detergent fiber concentration of corn silage and rumen inert bulk influences dry matter intake and ruminal digesta kinetics of growing steers.

Corn silage with high NDF concentration has the potential to reduce DMI because it has a greater filling effect in the rumen than low-NDF corn silage. Our objective was to determine whether ruminal fill influences DMI to the same extent with low- or high-NDF corn silage-based diets. Eight ruminally cannulated Holstein steers (198 +/- 13 kg) were randomly assigned to a 2 x 2 factorial arrangement of treatments in a replicated 4 x 4 Latin square design with 16-d periods. Treatments were diets containing corn silage from a normal hybrid (low-fiber; LF) or its male-sterile isogenic counterpart (high-fiber; HF), offered for ad libitum consumption to steers with or without rumen inert bulk (RIB). The LF and HF diets contained 33.8 and 50.8% dietary NDF, respectively. Rumen inert bulk was added at 25% of pretrial ruminal volume in the form of plastic-coated tennis balls filled with sand to achieve a specific gravity of 1.1 and a total volume of 7.5 L. No fiber level x inert bulk interactions were detected for DMI or NDF intake (P > 0.10), suggesting that DMI was limited to the same extent by physical fill at both levels of dietary fiber. Addition of RIB decreased DMI by an average of 10.7%, which was 65.5 g/L of added bulk. The HF diet depressed DMI by an average of 15.5%, increased NDF intake 27.1%, and reduced ruminal NDF turnover time by 21.0% compared to the LF diet (P < 0.01), with no effect on ruminal volume or amount of NDF in the rumen (P > 0.10). Addition of RIB also reduced ruminal NDF turnover time and amount of NDF in the rumen (11.8% and 20.7%, respectively; P < 0.01), with no change in ruminal digesta volume (P > 0.10). The HF treatment decreased digestibility of DM and GE (5.5 and 5.7%, respectively; P < 0.01) but increased NDF digestibility (10.4%; P < 0.01) compared to LF. Rumen inert bulk had no effect on digestibility of DM, NDF, or GE (P > 0.10). The lack of reduction in digesta volume with addition of inert fill suggests that DMI of light-weight steers receiving corn silage-based diets within a wide range of NDF concentrations was not regulated by ruminal distension alone.

Neutral detergent fiber concentration in corn silage influences dry matter intake, diet digestibility, and performance of Angus and Holstein steers.

Twelve Angus (237 +/- 13 kg) and twelve Holstein (235 +/- 15 kg) steers were used to determine whether corn silage-based diets with different NDF levels influence DMI to a similar extent in Angus and Holstein steers and as body weight of the steers increase. Steers were randomly assigned to individual slatted-floor pens and used in a crossover design consisting of six 14-d periods. Experimental diets contained corn silage from a normal hybrid (low-fiber; LF) and its male-sterile counterpart (high-fiber; HF) and were alternated each period. The LF and HF diets contained 33.8 and 50.8% NDF, respectively. The HF diet decreased (P < 0.01) overall steer mean DMI 14.0% relative to LF, with mean differences increasing as steers increased in BW (P < 0.01). Feeding the HF diet also reduced ADG by an average of 13.8% relative to the LF diet (P < 0.01). Holstein steers consumed 14.4% more DM and gained 14.3% faster (P < 0.01) than Angus steers. There was a fiber level x breed-type interaction (P = 0.08) for efficiency of gain. Angus steers receiving the HF diet had greater efficiency of gain than Angus steers consuming the LF diet; however, Holstein steers consuming the LF diet had greater efficiency of gain than those receiving the HF diet. The HF treatment reduced total-tract digestibility of DM and GE by 4.6 and 4.5%, respectively (P < 0.01), and decreased DE intake by 20.5% (P < 0.01) but increased apparent totaltract digestibility of NDF and ADF (9.4 and 8.4%, respectively; P < 0.01). Holstein steers had similar digestibility of DM and GE (P > 0.10) but had greater DE intake (P < 0.01) compared to Angus steers. There were fiber level x breed-type interactions for total-tract digestibility of NDF and ADF (P < 0.06). The difference in DM digestibility was negatively associated with the difference in DMI (r2 = 0.23; P < 0.01) for LF minus HF within Angus steers, but not within Holstein steers (P = 0.42). Total-tract digestibility of NDF and ADF was 4.1 and 3.4% lower for the HF diet but was only 1.1 and 0.6% lower for the LF diet when fed to Holstein compared to Angus steers. Results from this trial demonstrate that high-NDF corn silage-based diets reduced intake of both Angus and Holstein steers, and this reduction in DMI continued as steers increased in BW from 235 to 330 kg. Breed differences were also noted for digestible energy intake as influenced by fiber level.

Cyclooxygenase inhibitory and antioxidant cyanidin glycosides in cherries and berries.

Anthocyanins from tart cherries, Prunus cerasus L. (Rosaceae) cv. Balaton and Montmorency; sweet cherries, Prunus avium L. (Rosaceae); bilberries, Vaccinum myrtillus L. (Ericaceae); blackberries, Rubus sp. (Rosaceae); blueberries var. Jersey, Vaccinium corymbosum L. (Ericaceae); cranberries var. Early Black, Vaccinium macrocarpon Ait. (Ericaceae); elderberries, Sambucus canadensis (Caprifoliaceae); raspberries, Rubus idaeus (Rosaceae); and strawberries var. Honeoye, Fragaria x ananassa Duch. (Rosaceae), were investigated for cyclooxygenase inhibitory and antioxidant activities. The presence and levels of cyanidin-3-glucosylrutinoside 1 and cyanidin-3-rutinoside 2 were determined in the fruits using HPLC. The antioxidant activity of anthocyanins from cherries was comparable to the commercial antioxidants, tert-butylhydroquinone, butylated hydroxytoluene and butylated hydroxyanisole, and superior to vitamin E, at a test concentration of 125 microg/ml. Anthocyanins from raspberries and sweet cherries demonstrated 45% and 47% cyclooxygenase-I and cyclooxygenase-II inhibitory activities, respectively, when assayed at 125 microg/ml. The cyclooxygenase inhibitory activities of anthocyanins from these fruits were comparable to those of ibuprofen and naproxen at 10 microM concentrations. Anthocyanins 1 and 2 are present in both cherries and raspberry. The yields of pure anthocyanins 1 and 2 in 100 g Balaton and Montmorency tart cherries, sweet cherries and raspberries were 21, 16.5; 11, 5; 4.95, 21; and 4.65, 13.5 mg, respectively. Fresh blackberries and strawberries contained only anthocyanin 2 in yields of 24 and 22.5 mg/100 g, respectively. Anthocyanins 1 and 2 were not found in bilberries, blueberries, cranberries or elderberries.

Degradation products of cyanidin glycosides from tart cherries and their bioactivities.

The bioactive anthocyanins present in tart cherries, Prunus cerasus L. (Rosaceae) cv. Balaton, are cyanidin 3-glucosylrutinoside (1), cyanidin 3-rutinoside (2), and cyanidin 3-glucoside (3). Cyanidin (4) is the major anthocyanidin in tart cherries. In our continued evaluation of the in vivo and in vitro efficacy of these anthocyanins to prevent inflammation and colon cancer, we have added these compounds to McCoy's 5A medium in an effort to identify their degradation products during in vitro cell culture studies. This resulted in the isolation and characterization of protocatechuic acid (5), the predominant degradation product. In addition, 2,4-dihydroxybenzoic acid (6) and 2,4,6-trihydroxybenzoic acid (7) were identified as degradation products. However, these degradation products were not quantified. Compounds 5-7 were also identified as degradation products when anthocyanins were subjected to varying pH and thermal conditions. In cyclooxygenase (COX)-I and -II enzyme inhibitory assays, compounds 5-7 did not show significant activities when compared to the NSAIDs Naproxen, Celebrex, and Vioxx, or Ibuprofen, at 50 microM concentrations. However, at a test concentration of 50 microM, the antioxidant activity of protocatechuic acid (5) was comparable to those of the commercial antioxidants tert-butylhydroquinone (TBHQ), butylated hydroxytoluene (BHT), and butylated hydroxyanisole (BHA), and superior to that of vitamin E at 10 microM concentrations.

Brown midrib-3 corn silage improves digestion but not performance of growing beef steers.

The brown midrib-3 (bm3) gene mutation has been incorporated into corn plants to potentially improve fiber digestibility. The objectives of this study were to determine the effect of bm3 corn silage on digestion and performance of growing beef steers and to determine whether limiting intake would further enhance fiber digestibility of bm3 corn silage. A bm3 hybrid and its isogeneic normal counterpart were harvested at three-quarters kernel milk line. Neutral detergent fiber, ADF, and ADL were 4.5, 6.9, and 1.9 units lower, respectively, and DM was 5.4 units higher for bm3 than for normal silage. In Trial 1, eight ruminally fistulated Angus crossbred steers (224 +/- 24 kg) were randomly assigned to a 2 x 2 factorial arrangement of treatments in a replicated 4 x 4 Latin square design. Steers had ad libitum feed access or were restricted to 80% of ad libitum intake of diets containing 86% normal corn silage (Control) or bm3 corn silage (BMCS). The remainder of the diets consisted of soybean meal, urea, monensin, vitamins, and minerals. Dry matter intake was greater (P < 0.01) for steers offered ad libitum access to BMCS than for those with ad libitum access to the Control diet. The BMCS treatment resulted in improved (P < 0.05) apparent total-tract digestibility of DM, OM, NDF, and ADF. Mean concentration of total VFA and molar proportions of acetate were increased (P < 0.05) by feeding BMCS. There tended to be a DMI x hybrid interaction (P = 0.16) for apparent total-tract digestibility of NDF. When diets were offered ad libitum, BMCS increased NDF digestibility by 10.5 percentage units compared with Control, but, when DMI was limited, BMCS increased NDF digestibility by 15.8 percentage units. In Trial 2, 128 steer contemporaries of those used in Trial 1 (245 +/- 13 kg) were offered ad libitum access to BMCS or Control diets as used in Trial 1. After a 112-d treatment period, concentrate in the diet was increased, and all steers were fed a common finishing diet. During the 112-d treatment period, steers receiving BMCS consumed 0.45 kg more DM/d (P < 0.05) and had similar ADG (P > 0.10), compared with those steers receiving the Control silage. This resulted in poorer (P < 0.01) feed efficiency for steers receiving BMCS. Finishing phase and overall performance of the steers was not different (P > 0.10) due to treatment. Although feeding BMCS in growth-phase diets resulted in increased daily DMI and improved digestibility of DM and fiber, it did not result in improved steer feedlot ADG compared with Control silage.

Prevention of precancerous colonic lesions in rats by soy flakes, soy flour, genistein, and calcium.

The main purpose of this research was to determine whether diets containing soy products would inhibit the early stages of azoxymethane-induced colon cancer in F344 rats. Additional objectives were to determine whether feeding starch instead of sucrose, feeding additional calcium (0.5% compared with 0.1%), or feeding a low-fiber powdered enteral formula would influence early colon carcinogenesis. Colon cancer was initiated with 2 injections of azoxymethane (15 mg/kg body wt) and a 12-wk dietary treatment period was started 1 wk after the second injection. Precancerous colon lesions were assessed as foci with aberrant crypts (FAC). The mean numbers of FAC were 133 [soy concentrate (low concentration of phytochemicals)], 111 (starch substituted for sucrose), 98 [full-fat soy flakes (whole soybeans)], 87 (defatted soy flour), 77 (0.015% genistein), and 70 (0.5% Ca). The soy flour and full-fat soy flake diets contained 0.049% genistein derivatives (primarily glycosides), but were less effective in inhibiting the formation of FAC than the diet containing 0.015% genistein (as the aglycone). Eating soybeans and soy flour may reduce the early stages of colon cancer.

Alteration of the fiber and lipid components of a defined-formula diet: effects on stool characteristics, nutrient digestibility, mineral balance, and energy metabolism in humans.

Eighteen healthy males with a body weight of 70.0 +/- 3.1 kg consumed three defined-formula diets that varied only in their fiber and/or lipid components: 1) 6.4% fiber (100% soy polysaccharides) and 13.1% lipid [50% medium-chain triacylglycerols (MCTs), 40% corn oil, and 10% soy oil]; 2) 3.4% fiber (75% oat fiber, 17.5% gum arabic, and 7.5% carboxymethylcellulose) and 15.6% lipid (20% MCTs, 50% canola oil, and 30% high oleic acid safflower oil); and 3) 4.4% fiber (same as diet 2) and 14.5% lipid (same as diet 1). Consumption of diet 2 resulted in slightly firmer stools and provided the greatest amount of fecal output per unit fiber intake. Total dietary fiber (TDF) digestibility was lowest for men fed diets 2 and 3, but nitrogen and lipid digestibilities and energy metabolism criteria were not different among diets. Although mineral excretion patterns differed among treatments, fiber and lipid components of the diets appeared not to be responsible for these differences. Results indicate that fecal output can be maintained with a lower intake of a blend of oat fiber, gum arabic, and carboxymethylcellulose compared with soy polysaccharides. Except for TDF digestibility, alteration of amounts and/or sources of fiber and lipid components of defined-formula diets used in this experiment did not alter nutrient digestibility, energy metabolism, or mineral retention.

Dietary fiber for cats: in vitro fermentation of selected fiber sources by cat fecal inoculum and in vivo utilization of diets containing selected fiber sources and their blends.

Two experiments were conducted to evaluate the addition of single sources and blends of dietary fibers to cat diets. In Exp. 1, fermentability of selected fibrous substrates by cat fecal microflora was evaluated. After 24 h of fermentation, OM disappearance (OMD) and total short-chain fatty acid (SCFA) production were greatest (P < .05) for citrus pectin, guar gum, and locust bean gum, whereas Solka Floc resulted in the least (P < .05) OMD and total SCFA production. In Exp. 2, six diets were formulated based on results of Exp. 1. The highest (P < .05) digestibilities of DM and OM occurred when cats consumed the diet with no supplemental fiber, and the lowest (P < .05) digestibilities occurred when cats consumed the SCFA blend (SC) diet. Nitrogen and lipid digestibilities also were lowest (P < .05) for cats consuming the SC diet, whereas total dietary fiber (TDF) digestibility (P < .05) was greatest for cats consuming the beet pulp, SC, and combination blend diets. Fecal consistency scores were highest (P < .05) for cats consuming the SC diet, indicating liquid, unformed stools. In conclusion, the in vitro fermentation technique was reasonably accurate in predicting in vivo digestion of fiber. The SC diet, which contained the most fermentable fibers, severely decreased nutrient digestibility and resulted in poor stool characteristics. Diets that contain moderately fermentable fiber provide fermentation end products that may be important in maintaining the health of the gastrointestinal tract of the cat.

Portal and hepatic fluxes in sheep and concentrations in cattle ruminal fluid of 3-(4-hydroxyphenyl)propionic, benzoic, 3-phenylpropionic, and trans-cinnamic acids.

Extraction methods and HPLC procedures were developed for analysis of potential ruminal metabolites of dietary phenolics (reduced phenolics). Hepatic portal venous blood from wethers fed bromegrass, bermudagrass, ryegrass-wheat, and alfalfa hays also was analyzed for hippuric (HA), 3-(4-hydroxyphenyl)propionic (4OHPPA), benzoic (BA), 3-phenylpropionic (PPA), and t-cinnamic (CA) acids. Additionally, mesenteric arterial and hepatic venous blood was analyzed and, in conjunction with blood flow measurements, fluxes for portal-drained viscera (PDV) and liver were calculated. Ruminal fluid from four steers fed two levels of forage and two forage particle sizes in a Latin square design was analyzed for PPA and CA. 3-Phenylpropionic and benzoic acids were the most concentrated reduced phenolics identified in hepatic portal venous blood. Concentrations of PPA in ruminal fluid varied with ruminal disappearance of p-coumaric and ferulic acids. Additionally, hepatic portal venous concentrations of PPA were correlated (P < .05) with p-coumaric acid (r = .57) and ferulic acid (r = .67) intakes. Net release of PPA from PDV was observed, suggesting absorption of PPA from the gut. The liver removed PPA and BA with less efficiency. Given the relatively high concentrations of PPA in blood of ruminants, specific effects of this reduced phenolic on liver metabolism of ruminants should be assessed.

Dietary fiber for dogs: IV. In vitro fermentation of selected fiber sources by dog fecal inoculum and in vivo digestion and metabolism of fiber-supplemented diets.

Two experiments were conducted to evaluate single sources and blends of dietary fiber in dog food. In Exp. 1, 14 fibrous substrates were fermented in vitro using dog feces as the source of inoculum. Organic matter disappearance was lowest (P < .05; < 10%) for Solka Floc and oat fiber and greatest (P < .05; > 80%) for fructooligosaccharides (FOS) and lactulose. Solka Floc, oat fiber, gum karaya, and xanthan gum produced the least (P < .05; < 1 mmol/g of substrate OM) total short-chain fatty acids (SCFA). Lactulose, citrus pectin, and guar gum produced the greatest (P < .05; > 6.8 mmol/g of substrate OM) total SCFA. In Exp. 2, six diets were formulated based on results obtained in Exp. 1. Treatments included 1) beet pulp (BP), 2) Solka Floc (SF), 3) citrus pulp (CP), 4) stool blend (SB), 5) SCFA blend (SC), and 6) combination blend (CB). Digestibility of DM and total dietary fiber (TDF) was greatest (P < .05; 87.3 and 60.8%, respectively) for dogs consuming the SC diet. Feces from dogs fed SC were scored as more unformed and liquid in consistency than feces from dogs fed the other diets. Dogs consuming the SF and SB diets had the lowest (P < .05; 11.0 and 4.1%, respectively) TDF digestibilities. Organic matter disappearance values derived from substrates fermented in vitro reasonably predicted the fiber digestibility of diets fed to dogs. Moderately fermentable dietary fiber sources, such as BP, promote excellent stool characteristics without compromising nutrient digestibility, and may promote gastrointestinal tract health by optimizing SCFA production.

Ruminal digestion and glycosyl linkage patterns of cell wall components from leaf and stem fractions of alfalfa, orchardgrass, and wheat straw.

Samples of alfalfa, orchardgrass, and wheat straw were hand-separated into leaf and stem fractions that were subjected to in situ ruminal fermentation for various lengths of time to assess the rate and extent of degradation of cell wall neutral monosaccharides, uronic acids, acetyl groups, and hydroxycinnamic acids. A second objective was to measure the glycosyl linkage patterns of leaf and stem fractions of substrates before and after ruminal fermentation. Samples were fermented for 0, 6, 12, 24, 48, 96, and 192 h in each of two ruminally cannulated steers. In situ disappearance data were fitted to a first-order exponential equation to estimate the following substrate parameters: insoluble, potentially digestible fraction (fd), indigestible fraction (fi), and fractional rate constant of degradation of the potentially digestible fraction (k). Leaves contained larger concentrations of crude protein and smaller concentrations of cell wall components than did stem fractions. Estimates of fi were 7.3, 39.2, 22.1, 49.3, 27.7, and 36.3 for dry matter disappearances for alfalfa leaf, alfalfa stem, orchardgrass leaf, orchardgrass stem, wheat straw leaf, and wheat straw stem, respectively. Averaged across substrates, estimates of fi for arabinose, galactose, glucose, xylose, uronic acids, acetyl groups, and p-coumaric acid were 16.5, 11.4, 14.8, 31.2, 12.8, 25.3, and 22.6% in leaf fractions and 29.5, 19.9, 37.5, 56.2, 35.0, 52.4, and 44.6% in stem fractions. Rates of digestion of all monomeric components except galactose and xylose were greater (P < .05) for alfalfa than for orchardgrass or wheat straw. Differences in digestibility of cell wall components from leaf and stem fractions were greater in alfalfa and orchardgrass than in wheat straw. Glycosyl linkage analysis indicated that xylans in leaf and stem fractions of alfalfa, orchardgrass leaf, and wheat straw stem that resisted degradation had a lower degree of substitution with acid-labile constituents (i.e., other monosaccharides) than was found in original substrates. Different rates and extents of digestion of leaf and stem fractions of forages explain part, but not all, of the observed differences in digestibilities of cell wall monomers by ruminants.

Forage level and particle size effects on orchardgrass digestion by steers: II. Ruminal digestion kinetics of cell wall components.

Four steers (502 +/- 49 kg) with ruminal cannulas were used in a 4 x 4 Latin square experimental design with a 2 x 2 factorial arrangement of treatments to determine the effects of the dietary forage:concentrate ratio (96:4 and 60:40) and forage particle size (long hay and coarsely ground hay) on in situ ruminal digestion kinetics of orchardgrass hay DM and cell wall neutral monosaccharides, uronic acids, acetyl groups, and hydroxycinnamic acids. Dacron in situ bags containing orchardgrass hay were fermented for 0, 4, 8, 12, 18, 24, 48, and 96 h. Digestion profiles of DM and cell wall monomers in undigested residues recovered from the rumen were analyzed using a first-order, exponential equation to estimate the indigestible fraction (fi), the insoluble, potentially digestible fraction (fd), and the fractional rate constant (kd) of digestion of fd. Initial results indicated that fi was not consistently influenced by diet fed to the steers; thus, in situ digestion profiles were analyzed to estimate single fi and fd values common to all steers and diets and different estimates of kd for each steer x diet combination (16 total). Estimates of fi (percentage of original) for cell wall components were ranked in the following order: galactose (12.6), ferulic acid (13.9), arabinose (14.5), total uronic acids (15.4), glucose (19.8), xylose (28.4), p-coumaric acid (34.6), and acetyl groups (35.8).(ABSTRACT TRUNCATED AT 250 WORDS)

Forage level and particle size effects on orchardgrass digestion by steers: I. Site and extent of organic matter, nitrogen, and cell wall digestion.

Four steers (502 +/- 49 kg) with ruminal, duodenal, and ileal cannulas were used in a 4 x 4 Latin square experimental design with a 2 x 2 factorial arrangement of treatments to determine the effects of dietary forage:concentrate ratio (96:4 [96F] and 60:40 [60F]) and forage particle size (long hay [L] and coarsely ground hay [G]) on site and extent of digestion of OM, N, and plant cell wall monomeric components. Orchardgrass hay was the forage source used and was the sole source of cell wall material fed to steers (DMI = 88.6 g/kg BW.75). Diurnal variation in ruminal pH was greater when steers consumed 60F vs 96F (P < .01) and greater for G vs L (P < .10). Ruminal fluid volumes (liters) and daily outflows (liters/day) were greater (P < .05) when steers consumed 96F or L. True ruminal OM digestion (percentage of intake) was greater (P < .05) when steers consumed 60F (69.0) vs 96F (59.5) or L (65.8) vs G (62.7). Efficiency of net bacterial CP synthesis (grams of N/kilogram of true ruminal OM disappearance) was greater (P < .05) when steers consumed 60F (33.8) vs 96F (30.8). Total tract digestibilities of NDF and ADF were 63.3 and 53.0% when steers consumed 96F and were decreased (P < .05) to 52.3 and 43.8% when steers consumed 60F. Total tract digestibilities of plant cell wall arabinose, galactose, glucose, xylose, and uronic acids were 78.7, 69.7, 70.8, 67.6, and 79.7% when steers consumed 96F and were decreased (P < .05) when steers consumed 60F. Ruminal digestion accounted for greater than 90% of total tract digestion of all cell wall monosaccharide components when steers consumed 96F but accounted for 6 to 20 percentage units less of total digestion when steers consumed 60F. Total tract disappearances of cell wall acetyl groups, ferulic acid, and p-coumaric acid were 62.4, 79.4, and 50.6% when steers consumed 96F and were decreased (P < .05) to 49.7, 73.2, and 42.2% when steers consumed 60F. Addition of concentrate to diets, but not forage processing, decreased total tract digestibilities of cell wall components and shifted site of digestion to the lower gastrointestinal tract.

Vegetable fiber fermentation by human fecal bacteria: cell wall polysaccharide disappearance and short-chain fatty acid production during in vitro fermentation and water-holding capacity of unfermented residues.

Dietary fiber from eight vegetables (broccoli, carrot, cauliflower, celery, cucumber, lettuce, onion and radish) was analyzed for chemical composition and potential in vitro fermentation by human fecal bacteria. Total dietary fiber concentration of substrates ranged from 34.9 (broccoli) to 5.8 (cucumber) g/kg edible matter. Substrate fiber fractions were composed primarily of pectic substances and cellulose with smaller concentrations of hemicelluloses and lignin. Total dietary fiber residues isolated from substrates were fermented in vitro for 24 h with fecal bacteria obtained from each of three human volunteers. Substrate dry matter disappearance during fermentation was highest for carrot (63.7%) and lowest for cucumber (49.4%). Averaged across all substrates, disappearances of arabinose, galactose, glucose, mannose, xylose and uronic acids during fermentation were 96, 90, 54, 68, 51 and 97%, respectively. Short-chain fatty acid (SCFA) production during substrate fermentation averaged 10.5 mmol SCFA/g dry matter fermented. Averaged across all substrates, production of the major SCFA, acetate, propionate and butyrate, occurred in the molar ratio 76:14:10. Potential water-holding capacity of substrates was not influenced by fiber source and averaged 2.04 g H2O/g original substrate dry matter. Extent of substrate fermentation, SCFA production and substrate potential water-holding capacity were significantly different among inoculum donors, indicating that considerable inter-individual variation exists in the potential in vivo fermentation of vegetable fiber.

Fermentation of dietary fibre by human colonic bacteria: disappearance of, short-chain fatty acid production from, and potential water-holding capacity of, various substrates.

Several dietary fibre-rich substrates were fermented in vitro with human colonic bacteria obtained from each of three adult male subjects to assess the extent of substrate fermentation short-chain fatty acid (SCFA) production, and the potential effect of fermented residues on faecal bulk. Substrates tested were two varieties of oat hull fibre, gum arabic, carboxymethylcellulose (CMC), soy fibre, psyllium, and six blends containing oat fibre, gum arabic, and CMC in various proportions. All substrates contained greater than 900 g/kg of total dietary fibre except for CMC (816 g) and soy fibre (778 g). In vitro organic matter disappearance during fermentation was greatest for gum arabic (69.5%), intermediate for soy fibre (56.4%), and less than 20% for the two oat fibres, CMC, and psyllium. Averaged across substrates, acetate, propionate, and butyrate were produced in the molar proportion of 64:24:12. Potential water-holding capacity (PWHC) of substrates, a measure of faecal bulking potential, was greatest for CMC (13.5 g H2O/g substrate) and lowest for gum arabic (1.92 g) and soy fibre (1.71 g). Organic matter disappearance and SCFA production of blends were directly proportional to their gum arabic content. Blend PWHC was proportional to CMC content. In vitro procedures are useful in predicting the actions of fibre blends formulated to produce desirable effects in vivo.

Short-chain fatty acid production and fiber degradation by human colonic bacteria: effects of substrate and cell wall fractionation procedures.

Three dietary fiber sources (corn fiber, oat bran, wheat bran) were analyzed for chemical composition and potential fermentation by human colonic bacteria in vitro. Total dietary fiber (TDF) concentration of substrates was 64.3, 11.1 and 50.4 g/100 g dry matter for corn fiber, oat bran and wheat bran, respectively. Original material (ORIG), TDF fractions and simulated (SIM) cell wall fractions (produced by combining cellulose, hemicelluloses and pectic substances in proportions they represented in the cell wall) from each substrate were fermented in vitro for 6, 12, 18, 24 or 48 h using inoculum prepared from freshly voided feces from each of three human volunteers. Substrate dry matter remaining after 48 h of fermentation was 87.8, 39.8 and 73.5% for TDF fractions of corn fiber, oat bran and wheat bran, respectively. Disappearance of ORIG fractions was considerably greater than that of TDF due to fermentation of nonfibrous material. Disruption of cell wall structure during isolation of polysaccharide fractions allowed for dramatically increased fermentability of SIM relative to TDF. Averaged across all treatments, production of the short-chain fatty acids, acetate, propionate and butyrate, occurred in the molar ratio 63:21:16; however, profiles of short-chain fatty acids produced were influenced by both treatment and inoculum source. Extent of substrate fermentation varied among inoculum donors, implying that colonic microbial activities differ among individuals. Potential colonic fermentability of fiber sources was influenced by substrate, method of fiber preparation and inoculum source.

Fermentability of various fiber sources by human fecal bacteria in vitro.

Certain beneficial effects of fiber in the human diet may be mediated by short-chain fatty acids (SCFAs) produced during anaerobic fermentation in the colon. Two studies, both involving in vitro incubations with human fecal bacteria as inoculum, were conducted to assess fermentation of various fiber sources and to quantitate the SCFAs produced. In experiment 1, substrate fermentability based on total SCFA production ranked as follows: citrus pectin greater than soy fiber greater than sugarbeet fiber greater than pea fiber greater than oat fiber. Fermentation of soy fiber led to higher proportions of propionate and butyrate than did fermentation of other substrates. In experiment 2, fermentation of gum arabic, a mixture of arabic and guar, and apple pectin resulted in greater SCFA production than did fermentation of either oat fiber or corn bran. Fermentation of gums led to more propionate and butyrate production than did that of apple pectin. It may be possible to select fiber sources capable of supporting stipulated amounts of both total and individual SCFA production in the human colon.