Dietary fibre level and enzyme inclusion affect nutrient digestibility and excreta characteristics in grower pigs

An experiment was conducted with 12 grower pigs to determine the effects of (1) manipulating dietary neutral detergent fibre (NDF) level and (2) dietary inclusion of fibre‐degrading enzymes on nutrient digestibility and excreta characteristics in pigs. Four diets were formulated to contain three levels of NDF: 1, 66 g kg^?1 NDF (low fibre); 2, 121 g kg^?1 NDF (moderate fibre); 3, 222 g kg^?1 NDF (high fibre); 4, diet 3 plus 2.0 g kg^?1 enzyme. Increasing levels of dietary NDF linearly decreased dry matter and energy digestibilities (r² = 0.99, P < 0.05). Lowering dietary NDF from 222 to 121 g kg^?1 improved nitrogen digestibility by 13% (P < 0.01). Faecal production was decreased by 9% for each 1% decrease in dietary NDF content (r² = 0.99, P < 0.05). Inclusion of fibre‐degrading enzymes in the high‐fibre diet improved dry matter and energy digestibilities by 2 and 3% respectively, and reduced faecal production by 10% (P < 0.01). Faecal and manure (faeces plus urine) pH values from pigs fed the high‐fibre diet and the high‐fibre plus enzyme diet were lower than those from pigs fed the other experimental diets (P < 0.05). In conclusion, lowering the dietary NDF level or inclusion of fibre‐degrading enzymes in high‐fibre diets may offer relatively practical and easy methods for reducing waste production in pigs. © 2002 Society of Chemical Industry     

Composition and in vitro digestibility of raw versus cooked white‐ and colour‐flowered peas

Ten pea cultivars (four white‐flowered, Pisum sativum ssp. hortense, and six colour‐flowered, Pisum sativum ssp. arvense) grown in Latvia were analyzed and tested in in vitro experiments, as raw and cooked seeds. The colour‐flowered (CF) had a greater proportion of hulls and a higher acid detergent fibre (ADF) content than white‐flowered (WF) pea seeds (10.7 vs. 8.2% and 92.2 vs. 84.5 g/kg dry matter (DM), respectively). Three out of six CF varieties had a significantly greater amount of protein bound to neutral detergent fibre (NDF) than WF peas. The tannin content was higher in CF than in WF peas (8.46 vs. 0.37 g/kg DM). In vitro protein and amino acid digestibility was about 8% higher in WF than in CF varieties. Cooking decreased the tannin content in CF peas (8.46 vs. 5.51 g/kg DM) but had no effect on in vitro protein digestibility. Heat treatment reduced significantly trypsin inhibitor activity and amount of protein bound to NDF in CF and WF varieties (from 6.50 to 0.52 and from 6.54 to 0.46 trypsin inhibitor units (TIU)/mg DM; from 1.250 to 0.831 and 0.761 to 0.209 g N/100 g NDF, respectively). However, the protein bound to NDF content in pea DM increased in CF and decreased in WF varieties (from 1.525 to 2.145 and from 0.913 to 0.502 g N/kg DM, respectively). Cooking resulted in an increased NDF content over two times in both CF and WF pea seeds (from 122 to 259 and from 120 to 262 g/kg DM, respectively). The results suggest that colour‐flowered pea may be considered as an interesting dietary alternative to white‐flowered pea since cooking removes trypsin inhibitor activity (TIA), decreases tannins, and increases dietary fibre contents.     

Modification of in-vitro digestibility and cell-wall composition of cocksfoot,ryegrass and timothy by imazethapyr

Recent studies have shown that the compound imazethapyr (5-ethyl-2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)nicotinic acid) possesses growth regulatory activity and can be used to enhance nutritive value of grasses. However, little is known about possible effects of this material on fibre composition or potential fibre utilisation by ruminants. The objective of this research was to examine imazethapyr-treated cocksfoot (Dactylis glomerata L), ryegrass (Lolium perenne L × L multiflorum Lam), and timothy (Phleum pratense L) for possible treatment-induced changes in in-vitro digestibility and in concentrations of selected fibre constituents. Replicated field plots treated with imazethapyr at 0 (control) or 100 g ai ha^?1 during the vegetative (pre-elongation) stage of growth were harvested when controls were in the early stage of inflorescence emergence. Samples taken from treated plots 4 weeks post-treatment had higher in-vitro dry matter disappearance (IVDMD), lower neutral detergent fibre (NDF), lower acid detergent fibre (ADF), lower cellulose, lignin, and higher hemicellulose concentrations compared with controls. Imazethapyr treatment also reduced the concentration of p-coumaric acid in NDF, but had no effect on ferulic acid. The treatment effect on in-vitro NDF disappearance, however, was inconsistent among the grass species and was statistically non-significant (P = 0·10), implying that, under the conditions of this study, imazethapyr-related enhancements in IVDMD can be attributed primarily to a reduction in the amount of NDF and its associated constituents, as opposed to qualitative differences in NDF composition.     

The study of Clitoria Ternatea L. hay as a forage alternative in tropical countries. Evolution of the chemical composition at four different growth stages

The nutrients and the total carotenoids of samples of Clitoria rernatea L. hay harvested at four different stages of growth were analysed. Yields were also estimated. The results were: protein (N × 6.25), 23–19%; crude fibre, 29–38%; ether extract, 4.4–3.4%; Ash, 9–7%; neutral detergent fibre (NDF), 42–54%; acid detergent fibre (ADF), 38–47%; permanganate lignin, 14–16%; cellulose, 21–29%. Moreover, after being stored for 6 months, the samples have a carotenoids content of 587–400 mg kg^?1. All data refer to DM content. First year results reveal that the forage plant can give high annual yields of hay, (18–29 t ha^?1) with good palatability, readily accepted by cattle. In certain warm areas with low rainfall it could replace lucerne (alfalfa) Medicago sativa L.     

The influence of cooking technique on dietary fibre of boiled potato

Samples of twenty-five different cultivars of potatoes were prepared and examined after cooking by boiling and by pressure cooking, peeled and 'in the jacket' in a factorial design to study the effect of cooking on dietary fibre fractions of potatoes. Raw samples were prepared as control.
The samples were analysed for acid detergent fibre (ADF) and lignin by published procedures. Filtration problems were encountered with the published procedure for neutral detergent fibre (NDF) giving rise to lack of reproducibility. Reproducibility was restored by introducing a short incubation of the sample with α-amylase enzyme ( Bacillus subtilis ) prior to the normal detergent digestion.
The lignin content of all samples was < 0.25% on a dry matter basis. Both ADF and NDF increased on cooking but boiled samples did not differ from pressure cooked samples. Cooking 'in the jacket' gave higher ADF values than peeled samples but the effect was not observed for NDF values.
Cultivar differences were significant for both ADF and NDF values but as the samples were all from a single season's crop in a single field a definitive ranking is not possible.     

In vitro degradability of three forages: fermentation kinetics and gas production of NDF and neutral detergent‐soluble fraction of forages

The fermentation of the neutral detergent‐soluble (NDS) fraction of three forages (alfalfa hay, Italian ryegrass + oats hay and corn silage) was measured using a curve subtraction technique with in vitro gas production data from the whole forage (WF) and the isolated neutral detergent fibre (NDF). NDF disappearance and volatile fatty acid (VFA) production were determined. There was no significant difference between the VFA patterns from the whole forage and the isolated NDF. There were significant (P < 0.001) linear correlations between the volume of gas and moles of VFA produced and the mass of fibre digested in the NDF samples. Using the monophasic curve model, maximum gas production rates (R_M) for the whole forages and the isolated NDF and NDS fractions can be calculated. For all three forages we obtained R_M‐NDS > R_M‐WF > R_M‐NDF. Trends in the rates of gas and VFA production were similar in the whole forages. The NDF showed a high superimposition between substrate degradability and VFA production. Our experiment confirmed the curve subtraction technique as a simple method to obtain information on the size and digestion kinetics of the NDS fraction, which helps in understanding the nutritional significance of this important fraction of the forages studied. © 2001 Society of Chemical Industry     

Composition and in-vitro digestibility of carbohydrates of wheat plants harvested at bloom and soft-dough stages

Wheat plants (Triticum aestivum) were harvested at the bloom and soft-dough stages, separated into leaves + sheaths, stems and spikes, and the effect of stage of maturity on neutral detergent fibre (NDF) composition and degradability was studied, the accumulation of starch in the spikes compensated for the decrease in the degradability of NDF polysaccharides so that the in-vitro digestibility of the organic matter (OM) was not changed between the bloom and soft-dough stages. Minor compositional changes occurred in the NDF of the various botanical fractions which can hardly explain the drop in NDF degradability with maturity. There was a decline in the ratio of hemicellulose to lignin, and the changes in NDF-monosaccharide degradability were probably related to the extension of covalent bonding between those matrix components during maturation. Irrespective of botanical fraction and maturity stage, NDF xylose was less digestible than NDF glucose. Between bloom and soft-dough stages there was an increase of 36% in the yield of digestible OM.     

Composition and in vitro digestibility of raw versus cooked white- and colour-flowered peas

Ten pea cultivars (four white-flowered, Pisum sativum ssp. hortense, and six colour-flowered, Pisum sativum ssp. arvense) grown in Latvia were analyzed and tested in in vitro experiments, as raw and cooked seeds. The colour-flowered (CF) had a greater proportion of hulls and a higher acid detergent fibre (ADF) content than white-flowered (WF) pea seeds (10.7 vs. 8.2% and 92.2 vs. 84.5 g/kg dry matter (DM), respectively). Three out of six CF varieties had a significantly greater amount of protein bound to neutral detergent fibre (NDF) than WF peas. The tannin content was higher in CF than in WF peas (8.46 vs. 0.37 g/kg DM). In vitro protein and amino acid digestibility was about 8% higher in WF than in CF varieties. Cooking decreased the tannin content in CF peas (8.46 vs. 5.51 g/kg DM) but had no effect on in vitro protein digestibility. Heat treatment reduced significantly trypsin inhibitor activity and amount of protein bound to NDF in CF and WF varieties (from 6.50 to 0.52 and from 6.54 to 0.46 trypsin inhibitor units (TIU)/mg DM; from 1.250 to 0.831 and 0.761 to 0.209 g N/100 g NDF, respectively). However, the protein bound to NDF content in pea DM increased in CF and decreased in WF varieties (from 1.525 to 2.145 and from 0.913 to 0.502 g N/kg DM, respectively). Cooking resulted in an increased NDF content over two times in both CF and WF pea seeds (from 122 to 259 and from 120 to 262 g/kg DM, respectively). The results suggest that colour-flowered pea may be considered as an interesting dietary alternative to white-flowered pea since cooking removes trypsin inhibitor activity (TIA), decreases tannins, and increases dietary fibre contents.     

Condensed tannins: A factor limiting the use of cassava forage

Cassava (Manihot esculenta, Crantz), an important tropical root crop, is considered to have a good potential for use as a forage because leaf blades generally contain <20% crude protein (CP). However, neutral-detergent fibre (NDF) obtained from cassava leaf blades contains condensed tannins (CTs) and high levels of CP. The amount of CP in the NDF that is insoluble when treated with pepsin or protease is highly correlated with the amount of CTs in the NDF. CTs in the NDF are rich in prodelphinidin. CTs may be an important factor limiting the nutritive value of cassava forage.     

Phenolics and in-vitro degradability of protein and fibre in West African Browse

Relationships among soluble phenolics, soluble and insoluble proanthocyanidins (PAC), lignin, N, neutral-detergent fibre (NDF), and in-vitro degradability of protein and NDF were determined in 72 West African fodder trees and shrubs. Species were collected in the semi-arid (Niger), sub-humid (Nigeria) and humid/sub-humid (Benin) zones. Variation among species in chemical composition and in-vitro degradability of protein and NDF was large. Zones did not differ in mean content of phenolic compounds. Protein degradability was negatively correlated with soluble phenolics (r = ?0.34, P < 0.01) and soluble PAC (r = ?0.47, P < 0.001). NDF was positively correlated with soluble PAC (r = 0.44, P < 0.001), insoluble PAC (r = 0.28, P < 0.05) and lignin (r = 0.76, P < 0.001). NDF degradability was negatively correlated with soluble PAC (r = ?0.40, P < 0.001) and lignin (r = ?0.59, P < 0.001). Chemical composition and in-vitro degradability along with field observations can provide useful criteria for determining the nutritive value of browse species.     

Yield and composition of cell wall residues isolated from various feedstuffs used for non-ruminant farm animals

The contents of cell wall residue were measured in 14 common feedstuffs used for non-ruminant farm animals by utilising a technique involving pronase and α-amylase treatments. Comparison with the contents of neutral detergent fibre (NDF) revealed that the NDF procedure underestimated cell wall contents in the dicotyledonous plant materials. The losses of cell wall material due to the neutral detergent solution were correlated (r=0.931, P<0.01) with the amount of pectic substances present in the cell wall residues of the dicotyledonous plant materials. Cell wall residues were analysed for starch, crude protein, polysaccharides, condensed tannins, sulphuric acid lignin, acetyl bromide lignin, and ash. Condensed tannins in the cell wall residues of sorghum, rapeseed meal and field bean resulted in a large protein contamination (11.3–26.6%) of these residues and to an overestimation of their lignin content. Compositions of polysaccharides are discussed from chemical and nutritonal viewpoints.     

Phenolics,fibre and fibre digestibility in the crop residue from bird resistant and non-bird resistant sorghum varieties

The relationship between phenolics and parameters of in-vitro digestibility of neutral-detergent fibre (NDF) in leaves and stems from the crop residue of bird resistant (BR) and non-bird resistant (NBR) sorghum varieties was determined. The phenolics studied were lignin, insoluble proanthocyanidins, soluble red pigments and soluble phenolics as measured by absorbance (280 nm)and precipitation with ytterbium. Parameters of the digestibility of NDF studied were 48-h digestibility, potentially digestible NDF, rate of digestion and indigestible NDF as determined by non-linear regression analysis. Leaves from BR varieties were higher in most phenolics than leaves from NBR varieties. Digestibility of NDF at 48 h, potentially digestible NDF and rate of NDF digestion was lower in leaves from BR varieties. The indigestible NDF was higher in BR varieties. Phenolics in leaves were negatively correlated with digestibility of NDF at 48 h, potentially digestible NDF and rate of NDF digestion and positively correlated with indigestible NDF. Phenolics in stems had non-significant correlations with parameters of the digestibility of NDF except for a positive correlation between lignin and indigestible NDF. These results indicate that breeding for bird resistance in sorghum would lead to lower nutritive value of the crop residue.     

Urea treatment of whole‐crop triticale at four growth stages: effects on chemical composition and on in vitro digestibility of cell wall

The objective of this study was to evaluate the preservative and upgrading potential of urea added to whole‐crop triticale. Triticale, harvested at different growth stages according to Feekes' scale (10.51, 10.54, 11.1 and 11.2), was ensiled with four levels of urea (0, 30, 60 and 90 g kg^?1 dry matter (DM)) and stored in plastic bags for 60 days. Data were analysed as a factorial design with growth stage and urea level as the main factors. Urea was extensively hydrolysed (more than 90% of added urea). Urea breakdown was not affected by urea level (P > 0.05) but decreased significantly with growth stage (P < 0.001). Microbial activity measured by pH, volatile fatty acid production and total non‐structural carbohydrate concentration was significantly reduced by the urea level. Urea treatment significantly (P < 0.001) increased water‐soluble and ammonium nitrogen; more than 85% of the added nitrogen was retained. Application of urea at a rate of 60 and 90 g kg^?1 DM significantly (P < 0.05) reduced the neutral detergent fibre (NDF) content and increased (P < 0.05) the NDF and acid detergent fibre in vitro digestibility. Whole‐crop triticale harvested at later growth stages (approximately 60% DM) can be effectively preserved and upgraded by ensiling with 60–90 g urea kg^?1 DM. Copyright © 2006 Society of Chemical Industry     

Apparent inhibition to digestion by lignin in normal and brown midrib stems

Lignin, a cell wall component, limits digestibility of plant cell walls. Brown midrib (bmr) mutants of forages have lignin with altered chemical composition compared with their normal counterparts. The objectives of this study were to determine if bmr lignin is more inhibitory to digestion than is normal lignin and if bmr has a consistent effect on rate of digestion across species and environments. Extent and rate of in-vitro cell wall digestion of normal and bmr stems of sorghum (Sorghum bicolor (L) Moench, two comparisons), millet (Pennisetum americanum (L) Leeke) and maize (Zea mays L, two comparisons) were determined. Samples were incubated in rumen fluid, and data were fitted with a first-order, nonlinear model to estimate concentrations of potentially digestible neutral detergent fibre (PDNDF), digestion rate of PDNDF, concentration of indigestible residue (IR), and lag time before digestion. The NDF, acid-detergent fibre (ADF), and acid-detergent lignin (ADL) analyses were conducted sequentially on undigested samples. The IR: ADL ratio was 37% greater for bmr than for normal plants, which indicates that bmr lignin inhibits digestion more than normal lignin per unit of lignin. Digestion rate of PDNDF was faster in bmr than in normal counterparts in one of the two sorghum comparisons (difference of 59%) and in the millet comparison (difference of 27%), but in neither maize comparison. The bmr mutants were lower than normal genotypes in NDF (9%) and ADL (47%) concentrations. The PDNDF concentration was 19% greater for bmr than for normal lines. Thus, decreased lignin concentration in bmr mutants increased the extent of NDF digestion but did not consistently increase the rate of digestion.     

Influence of neutral detergent fibre and protein in Bengal Gram (Cicer arietinum) on the utilisation of proteins by albino rats

The influence of neutral detergent fibre from Bengal gram on the utilisation of protein in albino rats was studied. Four market samples of Bengal gram and Bengal gram Annegeri variety harvested at three different stages of maturity were used for the study. The legumes were first analysed for proximate principles and then used as the source of nitrogen and fibre in the rat diets. Their proximate composition was similar to the values reported in literature. The content of neutral detergent fibre increased with increasing crude fibre. Growth of weanling rats was assessed on the basis of protein efficiency ratio (PER). Digestibility coefficient (DC), biological value (BV), total nitrogen retention (TNR) and net protein utilisation (NPU) were determined. PER, NPU, DC and nitrogen retention decreased with increase in fibre content in the diet. PER of Bengal gram sample with 14% neutral detergent fibre (NDF) was significantly different from the PER of all other samples. Biological value, however, was not affected by the fibre content.     

Isolation of grass cell walls as neutral detergent fibre increases their fermentability for rumen micro‐organisms

Cell wall isolated from grasses as neutral detergent fibre (NDF) is fermented more readily than cell wall in the unfractionated forage by rumen organisms in vitro. In several experiments with Heteropogon contortus and Astrebla squarrosa the NDF digestibility at 48 h for the isolated cell wall was 8–18 units higher than for the unfractionated forage, with most of the difference appearing in the first 24 h of fermentation. Similar in vitro increases were obtained for Sorghum sp, wheat hay, bagasse and Lolium perenne and less so for Panicum maximum. The difference was not significant for Chloris gayana, nor for the tropical legumes Stylosanthes hamata, Clitoria ternatea and Lablab purpureus. For those grasses in which the above effect was statistically significant there was a significant relationship between NDF content of the unfractionated grass (x) and the ratio of NDF digestibility of isolated NDF to that of the unfractionated grass, as described by y=0.018x (P<0.01). For H contortus, kinetic analysis of gas produced from 0 to 48 h of in vitro incubation with rumen microbes showed an increased (from 0.016 to 0.020 h ⁻¹, P<0.001) rate of production from the slowly‐digested pool. Spear grass NDF incubated in the rumen in polyester bags had a higher NDF loss than unfractionated forage between 9 and 24 h and the difference was maintained after 24 h. Treatments in which amorphous silica was precipitated within NDF or leached from a grass substrate indicated that the enhanced rate in grasses was not due to removal of biogenic silica by the neutral detergent treatment. © 1999 Society of Chemical Industry     

FIBER CONTENT IN THE EDIBLE PORTION OF EIGHT MANDARIN ORANGES CULTIVARS

Eight commercial varieties of mandarin oranges grown in Spain (Nova, Ortanique, Satsuma, Marisol, Fortuna, Ellendale, Clementine and ecologic Clementine) were harvested in winter and analyzed for their fiber composition. The neutral detergent fiber (NDF) content, 21.32 ± 0.09%, was higher than the crude fiber (CF) content, 15.42 ± 0.10%, and the acid detergent fiber (ADF) content, 8.59 ± 0.05%. The CF contents were in the range of 14.55–16.50%, lower than previously reported, because only the edible portion was considered in this study. The relative content of CF of the eight cultivars studied was not consistent with those of the NDF and/or ADF. Clementine had the highest values of CF, but the lowest of NDF, with intermediate values of ADF. On the other hand, the cvs. Nova and Ortanique had the lowest values of CF, but the highest values of both NDF and ADF. Therefore, the most valuable mandarin orange cultivars, according to their fiber content, were traditional and ecologic Clementine, Nova and Ortanique.     

Lax leaf maize: cell wall composition and nutritional value

Forage nutritive value, which comprises traits such as digestibility, fibre, lignin and protein content, is an important criterion for maize (Zea mays L) harvested as silage. Lines with a characteristic phenotype (‘lax leaf’) could be useful sources of genes for improved nutritive value in maize. A study was conducted to characterise the cell wall composition of the lax leaf line. Lax leaf inbreds and inbreds representing ‘normal’ maize were evaluated for cell wall neutral sugars, uronic acids, Klason lignin and phenolic acids in five tissues from the ear node and the internode above it. Acid detergent fibre (ADF) and neutral detergent fibre (NDF) and 48 h in vitro true digestibility (IVTD) were predicted using near‐infrared reflectance spectrophotometry (NIRS) calibrated with a subset of the scanned samples. Lax leaf inbred tissues had lower levels of ADF, NDF, lignin and xylose and were more digestible than tissues from the inbreds representing ‘normal’ maize. It was not known whether the lax leaf phenotype resulted from alterations in nutritive value traits or whether laxness and nutritive value traits are independent from one another. A second study was conducted to determine the nature of genetic control of the lax leaf character and to determine the genotypic relation between the lax leaf character and nutritive value. A recombinant inbred mapping population was developed from a cross between the lax leaf line and an inbred line with stiff upright leaves. Whole‐plant samples from each recombinant inbred line were evaluated for ADF, NDF, acid detergent lignin (ADL) and IVTD of dry matter using NIRS. Laxness, measured by number of broken leaves, was associated with lower nutritive value in this population (genetic correlations 0.16–0.34), which was contrary to expectation. Amplified restriction fragment length polymorphism (AFLP) and simple sequence repeat (SSR) markers were used to identify linkage groups associated with the lax leaf character, digestibility and fibre content. Several linkage groups were associated with both the lax leaf character and nutritive value. Where these characters were associated with the same linkage group, the lax leaf parent allele was associated with greater laxness but reduced nutritive value. The lax leaf parent allele was associated with increased nutritive value in linkage groups unassociated with the lax leaf character. While the lax leaf line may be a good source for alleles for improved nutritive value, selection for laxness will not likely be accompanied by improvement in forage quality. © 2000 Society of Chemical Industry     

Storage of fresh and ensiled forages by freezing affects fibre and crude protein fractions

The effect of freezing on fibre and crude protein fractions of forages was determined. Fresh and ensiled lucerne and fresh bromegrass were processed immediately after collection or stored at ?25°C for 1 day or 1, 6 or 12 months before drying at 55°C. Samples were frozen quickly by submersion in liquid nitrogen or slowly at ?25°C. Samples which were not frozen were processed immediately or after 1 h delay at room temperature. All treatments were replicated (n = 3). Samples were analysed for crude protein (CP), trichloroacetic acid soluble CP (TSCP), phosphate buffer soluble CP (BSCP), neutral detergent insoluble CP (NDCP), acid detergent insoluble CP (ADCP), neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent sulphuric acid lignin (lignin) and ash. Freezing decreased BSCP and increased NDCP by more than 40% for bromegrass. Freezing also changed NDF, ADF, lignin, ash, CP and ADCP in different ways depending on forage type and length of time frozen. No significant effects were observed for method of freezing or a 1-h delay in processing. An additional experiment showed that freeze-drying resulted in less insoluble protein than ovendrying. Prior freezing of forages appeared inconsistently to change the extent of gaseous loss during drying, and resulted in precipitation of protein. These changes also affected fibre estimates. Fresh forages should not be frozen and thawed before analysis of protein or fibre fractions.