Apparent Digestibility Of Neutral Detergent Fiber Research Articles

Alkali-Treated Forage for Early Lactation Dairy Cows: Effect on Lactation Performance and Nutrient Digestibility

Our objective was to determine the effect of sodium hydroxide treatment (4g NaOH/100g forage DM) of an alfalfa-orchardgrass forage and its subsequent utilization by early lactation dairy cows. Forage was harvested as hay. Complete mixed diets consisted of 55% control or treated hay and 45% concentrate (DM basis) and were fed to eight early lactation Holstein cows in a crossover design. Chemical composition of hays and complete diets were similar. Intake of dry matter was greater when cows were fed treated hay (23.4 vs. 22.2 kg/d), as was milk yield (32.3 vs. 30.9 kg/d). Yield of 4% FCM, however, did not differ between diets (27.8 vs. 27.4 kg/d). Cows fed the treated hay diet had increased concentrations of total rumen volatile fatty acids and ruminal acetate, decreased ruminal isobutyrate concentration and pH, and increased apparent digestibility of NDF, ADF, hemicellulose, and lignin. Sodium hydroxide treatment also increased the proportion of potentially digestible DM and NDF compared with that of untreated forage. Alkali treatment improved the utilization of medium quality forage in the early lactation dairy cow.

Low-Quality Roughages in High-Concentrate Pelleted Diets for Sheep:Digestion and Metabolism of Nitrogen and Energy as Affected by Dietary Fiber Concentration

Two trials were conducted to evaluate effects of, and interactions between, level and source of fiber in the diet on ruminal environment, microbial protein synthesis, nutrient digestion and flow of digesta through the gastrointestinal tract of multiple-fistulated sheep (trial 1; 4 X 4 Latin square design) and on ruminal, digestive and metabolic characteristics of early-weaned lambs (trial 2; randomized complete block design; 3 periods). All diets tested were pelleted and were formulated to contain either 39% or 25% neutral detergent fiber (NDF), with corncobs or cottonseed hulls (CSH) as the major NDF (roughage) sources. In trial 1, dry-matter (DM) and organic-matter (OM) digestibilities were not different (P greater than .05) among treatments. Digestibility of NDF was higher (P less than .05) with high-fiber. Bacterial N synthesis (g N/kg OM truly digested) was not different (P greater than .05) among treatments. Molar proportion acetate was higher (P less than .05) and molar proportion propionate lower (P less than .05) when sheep were fed high-fiber diets. In trial 2, apparent DM digestibility was higher (P less than .05) for lambs fed diets containing corncobs. Energy digestibility was higher (P less than .05) at the low-fiber level and for lambs fed diets containing corncobs. Apparent NDF digestibility by lambs was higher (P less than .05) at the high-fiber level and for lambs fed diets containing corncobs. Nitrogen retained (percentage of N intake) was higher (P less than .05) for lambs fed diets containing CSH. Ruminal pH and molar proportion acetate were higher (P less than .05) and molar proportion propionate lower (P less than .05) for lambs fed high-fiber diets. Although responses to corncob vs CSH inclusion in high-energy pelleted diets differ, both roughages are effective as fiber sources in sheep diets.

The effect of supplementation with maize starch and level of intake of perennial ryegrass (Lolium perenne cv. Endura) hay on the removal of digesta from the rumen of sheep.

1. Eight wether sheep were offered a diet of perennial ryegrass (Lolium perenne cv. Endura) hay once daily at two levels of intake (11 and 16.5 g dry matter (DM)/kg live weight (LW] with or without maize starch (175 g DM/kg hay DM). The experiment consisted of four periods, each lasting 32 d. Rates of digestion of the hay were measured by incubation in dacron bags and rates of passage using chromium-mordanted hay. Rumen pool sizes of DM, organic matter and fibre were measured by emptying the rumen. 2. The inclusion of starch in the diet appeared to increase significantly (P less than 0.01) the lag phase before the start of fibre digestion, as observed both in the dacron bag studies and in the slower initial disappearance of digestible neutral-detergent fibre (NDF) from the rumen recorded by emptying of rumen contents. However, there was no significant effect of starch on apparent digestibility of fibre in the whole tract. 3. The main effect of increasing the level of feeding was to increase the rate of passage with a consequent decrease in overall digestibility. The fractional rate of passage increased from 0.0318 to 0.0400 as the level of feeding increased, while apparent digestibility of NDF decreased from 0.755 to 0.724. 4. On all treatments the weight of indigestible fibre in the rumen remained more or less constant between 5, 10 and 15 h after feeding, but was significantly lower at 24 h. These results suggest that a high proportion of the outflow of material from the rumen not associated with feeding appears to occur during the second half of the feeding cycle.

Effect of Preventing Coprophagy in the Rat on Neutral Detergent Fiber Digestibility and Apparent Calcium Absorption

The effect of coprophagy on apparent neutral detergent fiber (NDF) digestibility, and calcium absorption was evaluated by housing rats in four types of cages: regular, metabolic, and two anticoprophagy cages: a short linear tube cage which allowed the rat forward and backward movement of about one-half a body length and a long tube cage assembled to form a square which allowed the rat to move in one direction through the tube but not turn around. Three-day weight gains of animals in the regular or metabolism cages were greater than those of rats housed in either anticoprophagy cage. In contrast, average food intake did not differ among the four housing conditions. Wet, but not dry, fecal weights were greater in the two groups of rats in the anticoprophagy cages. Neither fecal NDF (% dry wt) nor apparent NDF digestibility was affected by housing conditions. Apparent calcium absorption was decreased by the anticoprophagy housing. The differences in body weight and apparent calcium absorption suggest that prevention of coprophagy in the rats produces significant changes in the efficiency of food and nutrient utilization. The failure to detect differences in NDF digestibility indicates that coprophagy has little impact on the study of fiber digestibility.

Breath hydrogen and methane: poor indicators of apparent digestion of soy fiber

To examine whether end-alveolar breath hydrogen and methane could be used as indicators of fiber digestion in humans, 16 male subjects were fed four fiber-free, complete liquid diets with 0, 30 g (heat processed), 30 g, and 60 g/day soy polysaccharide. Breath hydrogen was measured hourly and breath methane every 4 h on days 6 and 8 of each study period. Feces were collected, homogenized, dried, and analyzed for neutral detergent fiber (NDF). NDF in diets was determined and apparent NDF digestibility calculated. NDF from soy was extensively fermented, <80%, on the fiber-containing diets. No significant relationship was found between breath-gas excretion and fiber digestion, although breath-gas values varied greatly. Breath hydrogen and methane were not significantly different when subjects consumed diets containing 0, 30, or 60 g soy polysaccharide.

Composition of Fecal Fiber from Human Subjects

This research addresses two problems of fecal fiber analysis: the nitrogen in fecal neutral detergent fiber (NDF); and the impact of sodium sulfite on NDF yield and composition. Fecal samples for analysis were collected from healthy adults during a study of the effect of a wheat bran supplement on bowel function. When sodium sulfite, originally a component of neutral detergent solution, was omitted, the yield of fecal NDF, the concentration of apparent lignin in the NDF and the amount of nitrogen recovered in both the NDF residue and the lignin increased. These data support a previous report by Van Soest that the sulfite attacks lignin. We present evidence that the effect of sodium sulfite also could be one of inhibiting the formation of Maillard products, which are detected as lignin, during the reflux step of the NDF method. Three different fractions of nitrogen were identified in fecal NDF: the fraction eliminated by sodium sulfite; a fraction removed by dilute acid; and the fraction that remained in Klason lignin. Apparent NDF digestibilities were calculated several ways by using correction factors to account for this nitrogen. Only the subtraction of Klason lignin from fecal NDF eliminated the one negative digestibility we observed.

The digestion of fibre by pigs. 1. The effects of amount and type of fibre on apparent digestibility, nitrogen balance and rate of passage.

The effects of the amount and the type of dietary fibre on the apparent digestibility (AD) by growing pigs of neutral-detergent fibre (NDF) and NDF components, on nitrogen balance and on the rate of passage of digesta were studied using a semi-purified basal diet and fibre in the forms of soya-bean hulls, lupin (Lupinus sp.) hulls, pea (Pisum sativum) hulls, wheat bran, maize hulls, maize cobs, oat hulls and lucerne (Medicago sativa) stems. Both the amount and the type of dietary fibre significantly influenced the AD of dietary dry matter, N and energy. The AD of NDF and of NDF components was markedly affected by the type and the amount of fibre in the diet. The proportion of NDF digested ranged from 0.016 to 0.905, of cellulose from 0.026 to 0.931 and of hemicellulose from 0.010 to 0.999. N retention by the pigs ranged from 12.9 to 25.8 g/d and with some fibres there was a tendency towards increased N retention with increasing intakes of NDF. Rate of passage of digesta, expressed as the 50 and 95% excretion times of stained feed particles, ranged from 22.2 to 85.1 h and 40.0 to 117.1 h respectively. Large individual variations in rate of passage occurred but, in general, the rate of passage tended to increase with increasing intakes of NDF. No strong associations between the rate of passage of digesta and apparent digestibility of NDF components were observed. The results suggest that the extent of fibre digestibility depends predominantly on the origin of the fibre and to a lesser extent on the amount of fibre in the diet.

The effect of free and protected oils on the digestion of dietary carbohydrates between the mouth and duodenum of sheep.

Sheep fitted with rumen and re-entrant duodenal cannulas were given diets of approximately 200 g hay and 400 g concentrate mixture alone, or supplemented daily with 40 g linseed or coconut oils free or protected with formaldehyde-casein in a 5 x 5 Latin-square arrangement. Chromic oxide paper was given as a marker at feeding time and passage to the duodenum of neutral-detergent fibre (NDF) and different sugars were estimated from the values for constituent:marker at the duodenum. Contributions of microbial carbohydrates to these flows were estimated from amounts of RNA present. The carbohydrate composition of mixed rumen bacteria from sheep rumen digesta were similar regardless of diet. Of the sugars entering the duodenum all the rhamnose and ribose and 0.51, 0.24 and 0.35 of the mannose, galactose and starch-glucose respectively, were contributed by the microbes. Virtually all the arabinose, xylose and cellulose-glucose were contributed by the diet. For sheep receiving the basal ration, coefficients of digestibility between mouth and duodenum, corrected where necessary for microbial contribution, were 0.95, 0.66, 0.67, 0.62, 0.45 and 0.51 for starch-glucose, mannose, arabinose, galactose, xylose and cellulose-glucose respectively. Corresponding values when free-oil-supplemented diets were given were 0.95, 0.55, 0.38, 0.55, 0.01 and -0.02 respectively. Values for diets supplemented with linseed oil or coconut oil did not differ significantly. Addition of protected oils to the basal feed also resulted in depressed digestibilities of dietary structural sugars but to a far lesser extent than those observed with the free oils. Apparent digestibility of NDF was altered in the same direction as those of the main structural sugars, averaging 0.50, 0.17 and 0.29 in animals receiving the basal, free-oil-supplemented or protected-oil-supplemented diets respectively. The reasons for the difference between NDF and discrete carbohydrate analytical totals are discussed.

BROWN MIDRIB-3 VERSUS NORMAL CORN PLANTS (Zea mays L.) HARVESTED AS WHOLE PLANT OR STOVER AND FROZEN FRESH OR PRESERVED AS SILAGE FOR SHEEP

Brown midrib (bm) mutants of corn contain less lignin than normal (N) corn. No previous research has compared whole plant and stover of bm and N corn plants. Corn plants from N and isogenic mutant bm3 were harvested as whole plant (WP) or stover (St), and stored fresh frozen (F) or as fermented silage (S). A 2 × 2 × 2 factorial arrangement was used for the factors of mutant type (bm3 and N), plant portion (WP and ST) and storage method (S and F). A 9-day metabolism study was conducted, with 32 wethers assigned to the following forage combinations: (1) bm3WPS; (2) bm3StS; (3) NWPS; (4) NStS; (5) bm3WFF; (7) NWPF; and (8) NStF. Lignin content of bm3 forages was about 2 percentage units less than that of their N counterparts. Digestibilities of dry matter (DM), energy, acid and neutral detergent fiber (ADF and NDF) and cellulose were greater for the bm3 forages and intakes of digestible nutrients were 20–25% higher for those forages. These findings were attributed to the reduced and altered lignin of bm3. Comparison of WP and St showed that DM digestibility, DM intake (DMI), digestible DMI and digestible energy and crude protein intakes were greater for WP than for St. Differences between storage methods were not significant. A plant type by storage method interaction was found for the apparent digestibility of NDF, ADF, cellulose and energy, and for the intake of digestible NDF and ADF. These measurements decreased for WP and increased for St with ensiling. The increase in St digestibility could have been due to partial degradation of the cell wall, while the decrease in WP digestibility could have been due to a larger loss of NDF and soluble carbohydrates during fermentation. Tendencies existed for the feeding value of bm3St (F and S) to surpass that of NSt (F and S) and to approach the feeding value of NWP (F and S). Key words: Brown midrib-3, corn plants, silage, lignin, corn stover, sheep

Apparent digestibility of neutral detergent fiber in elderly and young adults

These experiments assessed the ability of the neutral detergent fiber (NDF) method to remove starch and nitrogen from food NDF residues, and nitrogen and endogenous secretions from fecal NDF residues; and compared indices of bowel function, including apparent NDF digestibility, of nine elderly subjects to those of six young women. Subjects consumed similar, controlled "low fiber" diets containing foods typically eaten in the United States. Nitrogen and starch contents of food composite NDF were determined in NDF obtained by the hog alpha amylase modification of the Van Soest procedure, whereas the nitrogen content of fecal NDF was determined using NDF obtained by the unmodified procedure. The modified Van Soest method adequately removed nitrogen and starch from food NDF, but fecal NDF contained nitrogen. Both groups digested the majority of the NDF, 63 and 70% for the elderly and young subjects, respectively. Apparent fiber digestibility, which was measured several times in each subject, increased to 69 and 75% for the two groups, respectively, when a correction was made for the nitrogen in the fecal NDF. Mean gastrointestinal transit time and frequency of defecation of the two age groups were comparable, whereas mean daily wet and dry stool weights of the elderly were larger than those of the young women. These results suggest that the bowel of the elderly may function as well as that of the young adult.

Neutral Detergent Fiber, Hemicellulose and Cellulose Digestibility in Human Subjects

The fate of dietary fiber and its components was examined in seven women consuming low cellulose (LC) and high cellulose (HC) diets, each for about 1 month. The diets were of constant daily composition and differed only in that the HC diet contained an additional 16 g/day non-nutritive fiber (Solka Floc), which increased the neutral detergent fiber (NDF) of the diet from 9.5 to 23.5 g/day and Crampton and Maynard cellulose from 5.4 to 19.3 g/day. When apparent fiber digestibilities during 5-day periods were determined, both NDF and cellulose digestibilities varied greatly and inconsistently in each subject throughout both diet periods. Therefore, samples were pooled to form a single 20–30 day composite for each subject during each diet. Mean apparent NDF digestibility, after correcting for protein contamination in fecal NDF, was 70.4 ± 7.3% during the LC diet and decreased to 23.0 ± 15.0% during the HC diet. Cellulose digestibility was 69.7 ± 10.7% without and 15.7 ± 17.4% with the added cellulose. Hemicellulose was calculated as NDF minus cellulose. When the fecal NDF was corrected for protein contamination, hemicellulose digestibility averaged 71.7 ± 5.4% during the LC diet and 51.0 ± 7.9% during the HC diet. In a separate experiment, 16 g/day Solka Floc was ingested with a semi-purified liquid diet and only 8% of the cellulose was digested. These results suggest that more than half of the fiber in a LC diet containing fruits, vegetables and refined grains in degraded, while the apparent digestibility of refined cellulose is minimal.neutral detergent fiber hemicellulose cellulose dietary fiber digestibility