Evaluation of detergent extraction procedures for characterising carbohydrate components in ruminant feeds and digesta

Steers fitted with simple rumen and abomasal cannulas were given isoenergetic diets of approximately equal amounts of untreated (UT) barley straw and concentrates (flaked maize + tapioca) alone (BS) or with urea (BSU) or fishmeal (BSF). Similar diets were also given in which the barley straw had been treated (AT) with NaOH (BSA, BSAU and BSAF respectively). The diets were given in a 6 × 6 Latin square design. Feed components and abomasal digesta samples were analysed for neutral (NDF) and acid (ADF) detergent fibres and for monosaccharide constituents of structural polysaccharides. Hemicellulose contents were estimated as the sum of xylose + arabinose (X + A) and by the difference between ash-free NDF and ash-free ADF (NDF-ADF). Cellulose was estimated as β-linked glucose (C) and by the difference between ash-free ADF and lignin (ADF–L).¹⁰³ Ruthenium and PEG were given as flow markers and flows (g24h^?1) at the abomasum of carbohydrate components estimated in these ways were calculated. Approximately 98% (by wt.) of the cellulose (C) found in original feed and digesta samples was recovered in both NDF and ADF. Recoveries of hemicellulose (X + A) in NDF from UT straw, AT straw and abomasal digesta were approximately 92, 48 and 50%, respectively. The ADF fraction of feeds and digesta contained 3–6 and 10–17% of the nitrogen and xylose, respectively, present in the original samples. Mouth to abomasum digestibilities of hemicellulose (NDF– ADF) for diets BS, BSU, BSF, BSA, BSAU and BSAF were 39, 62, 67, 29, 61 and 76%, respectively. Corresponding values for cellulose (ADF–L) were 37, 34, 50, 45, 48, and 63%, respectively. The use of NDF–ADF and ADF–L as measures of hemicellulose and cellulose contents, respectively, of feeds and digesta, and the digestibility of these carbohydrate fractions between mouth and abomasum of steers are discussed.     

Evaluation of pretreatment with Pleurotus ostreatus for enzymatic hydrolysis of rice straw

The effects of biological pretreatment of rice straw using four white-rot fungi (Phanerochaete chrysosporium, Trametes versicolor, Ceriporiopsis subvermispora, and Pleurotus ostreatus) were evaluated on the basis of quantitative and structural changes in the components of the pretreated rice straw as well as susceptibility to enzymatic hydrolysis. Of these white-rot fungi, P. ostreatus selectively degraded the lignin fraction of rice straw rather than the holocellulose component. When rice straw (water content of 60%) was pretreated with P. ostreatus for 60 d, the total weight loss and the degree of Klason lignin degraded were 25% and 41%, respectively. After the pretreatment, the residual amounts of cellulose and hemicellulose were 83% and 52% of those in untreated rice straw, respectively. By enzymatic hydrolysis with a commercial cellulase preparation for 48 h, 52% holocellulose and 44% cellulose in the pretreated rice straw were solubilized. The net sugar yields based on the amounts of holocellulose and cellulose of untreated rice straw were 33% for total soluble sugar from holocellulose and 32% for glucose from cellulose. The SEM observations showed that the increase in susceptibility of rice straw to enzymatic hydrolysis by pretreatment with P. ostreatus is caused by partial degradation of the lignin seal. When the content of Klason lignin was less than 15% of the total weight of the pretreated straw, enhanced degrees of enzymatic solubilization of holocellulose and cellulose fractions were observed as the content of Klason lignin decreased.     

Dietary fibre and components of the nitrogen-free extract of almond kernels

Determinations of neutral and acid detergent fibre residues (NDF and ADF), hemicellulose, cellulose and lignin in almond nuts (Prunus amygdalus) were carried out. The NDF content was about 5% while the crude fibre content was only approximately 2%. The composition of several components of nitrogen-free extract (NFE) such as soluble sugars, starch, gums and mucilages and pectins were also determined, and the results are discussed.     

Cellulose, Hemicellulose and Lignin Content of Raw and Cooked Processed Vegetables

The NDF, ADF, cellulose, hemicellulose and lignin contents of five frozen vegetables (raw and boiled) and five canned vegetables (two of them fried) have been studied. In general, it was observed that boiling resulted in an increase in the NDF, ADF and cellulose content. There was also a slight increase in hemicellulose values. The lignin contents of most vegetables did not change upon boiling. When the cooking process was frying, a drastic decrease of NDF, ADF, cellulose, and lignin contents occurred, while the amount of hemicellulose changed slightly in the vegetables analyzed.     

Cellulose, Hemicellulose and Lignin Content of Raw and Cooked Spanish Vegetables

The content in NDF, ADF, cellulose, hemicellulose, and lignin of 22 raw and 19 cooked vegetables (14 boiled, and 5 fried) widely consumed among the Spanish population was determined according to the method of Van Soest. Cooking generally increases the NDF, ADF and cellulose content on a dry weight basis. Normal size servings of the vegetables were prepared and their NDF, cellulose, hemicellulose and lignin contents calculated. We observed that, with vegetables of common use, a total amount of 15–20 g/day of these fiber components can be obtained; according to current knowledge this implies beneficial physiological effects for a broad human pathology.     

Degradation rate and chemical composition of different types of alkali-treated straws during rumen digestion

The degradation in the rumen and change in chemical composition of untreated and four samples of alkali-treated barley straw were studied in farm-scale treatments with ammonia, ‘dry’ sodium hydroxide and two different aqueous sodium hydroxide systems. The alkali treatments increased the fraction soluble in organic solvents and decreased the lignin content (determined as Klason lignin). The amounts of cellulose and arabinoxylans were not significantly changed. The degree of rumen degradability increased with the order of alkaline treatment given above. The degradation rates of dry matter and the NDF fraction were parallel to each other but varied considerably with the treatments. The two most efficient aqueous alkaline treatments showed a degradation rate four times that of untreated straw. For these two samples the arabinoxylans were solubilised faster than cellulose during the first part of the incubation. In the other samples the degradation of arabinoxylans and cellulose ran almost parallel. During the rumen incubation the lignin content of the straw residues increased for all samples. There was an inverse relationship between the content of p-coumaric and ferulic acids on the degree of digestibility. A relationship between acetyl groups and digestibility was not found.     

Effects of sodium hydroxide on cereal straws in relation to the enhanced degradation of structural polysaccharides by rumen microorganisms

The action of sodium hydroxide on the rate and extent of loss of wall polysaccharides from wheat and barley straws incubated in the rumen of the sheep was studied using a nylon bag technique. Cellulose loss reached a maximum in straws treated with 10 g NaOH 100 g^?1 straw. Further increase in amounts of alkali applied resulted in additional solubilisation of straw constituents, particularly xylan, but did not further enhance cellulose degradation. Rates of degradation of isolated straw, cotton and wood celluloses correlated with three of four measures of cellulose crystallinity obtained by X-ray diffraction and infrared analysis. Treatment of cellulose samples with 20 g NaOH 100 g^?1 cellulose did not affect rates of loss or produce detectable changes to cellulose morphology. Loss of acetic acid esters, which accompanied alkali treatment, did not relate to improvements to digestibility. The rate of loss of cellulose from delignified neutral detergent fibre (NDF) was that shown by the isolated straw cellulose, despite the presence of acetylated hemicellulose. Deacetylation of delignified NDF with NaOH or sodium methoxide did not enhance rates of xylose or cellulose loss. In lignified wall material (NDF) the molar ratio acetyl:xylose (approximately 1:3.5) and proportion of the major phenolic acids (p-coumaric and ferulic acids) remained essentially constant throughout the course of degradation in the rumen. It is suggested that loss of phenolic acids, while not directly contributing to digestibility enhancement, may model the susceptibility of ester linkages formed between polysaccharide and polyphenolic material to alkali. The extent of solubilisation of p-coumaric acid produced by NaOH showed a linear relationship with cellulose digestibility. An upper limit of 40% acid detergent lignin and 55% of total phenolics were released by NaOH, the extent of release closely paralleling cellulose digestibility. Phenolic material resistant to alkali remained associated with wall polysaccharides and was not released from nylon bags until over 50% of cellulose (and hemicellulose) had been degraded.     

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.     

Effect of lignin linkages with other plant cell wall components on in vitro and in vivo neutral detergent fiber digestibility and rate of digestion of grass forages

The objective of this study was to correlate in vitro and in vivo neutral detergent fiber (NDF) digestibility (NDFD) with the chemical composition of forages and specific chemical linkages, primarily ester- and ether-linked para-coumaric (pCA) and ferulic acids (FA) in forages fed to dairy cattle. The content of acid detergent lignin (ADL) and its relationship with NDF does not fully explain the observed variability in NDFD. The ferulic and p-coumaric acid linkages between ADL and cell wall polysaccharides, rather than the amount of ADL, might be a better predictor of NDFD. Twenty-three forages, including conventional and brown midrib corn silages and grasses at various stages of maturity were incubated in vitro for measurement of 24-h and 96-h NDFD. Undigested and digested residues were analyzed for NDF, acid detergent fiber (ADF), ADL, and Klason lignin (KL); ester- and ether-linked pCA and FA were determined in these fractions. To determine whether in vitro observations of ester- and ether-linked pCA and FA and digestibility were similar to in vivo observations, 3 corn silages selected for digestibility were fed to 6 ruminally fistulated cows for 3 wk in 3 iso-NDF diets. Intact samples and NDF and ADF residues of diet, rumen, and feces were analyzed for ester- and ether-linked pCA and FA. From the in vitro study, the phenolic acid content (total pCA and FA) was highest for corn silages, and overall the content of ester- and ether-linked pCA and FA in both NDF and ADF residues were correlated with NDF digestibility parameters, reflecting the competitive effect of these linkages on digestibility. Also, Klason lignin and ADL were negatively correlated with ether-linked ferulic acid on an NDF basis. Overall, esterified FA and esterified pCA were negatively correlated with all of the measured fiber fractions on both a dry matter and an NDF basis. The lignin content of the plant residues and chemical linkages explained most of the variation in both rate and extent of NDF digestion but not uniformly among forages, ranging from 56 to 99%. The results from the in vivo study were similar to the in vitro data, demonstrating the highest total-tract aNDF digestibility (70%; NDF analysis conducted with α-amylase and sodium sulfite) for cows fed the corn silage with the lowest ester- and ether-linked pCA content in the NDF fraction. In this study, digestibility of forage fiber was influenced by the linkages among lignin and the carbohydrate moieties, which vary by hybrid and species and most likely vary by the agronomic conditions under which the plant was grown.     

Evaluation of Myrothecium verrucaria as a nutrient source for ruminants

The soil saprophytic fungus Myrothecium verrucaria was cultivated from glucose, starch, or xylan as the carbon source, and the biomass was compared with three selected feedstuffs. Fungal biomass was analyzed for nitrogen, protein, lipid, water soluble fraction, hemicellulose, cellulose, lignin, and residual ash, and the in vitro dry matter disappearance was determined. The chemical composition of M. verrucaria varied with substrate. In nitrogen content, the fungal biomass was more similar to alfalfa hay than to milo stalks or wheat straw. Content of water soluble fraction of fungal biomass was between those of alfalfa hay and milo stalks; content of hemicellulose was between those of milo stalks and wheat straw. The fungal fractions identified as cellulose and lignin varied widely with substrate. The fungal biomass was less digestible than alfalfa hay but more digestible than milo stalks or wheat straw. There may be potential uses of this organism in upgrading nutritive value of low-quality forages.     

超滤分离麦草浆黑液主要成分的研究

利用截留相对分子质量分别为1K,5K,10K的改良纤维素膜对不同浓度的麦草浆黑液进行了超滤研究,研究结果表明：在种膜中,截留相对分子质量为10K膜的水通量最大,5K膜的水通量最小,黑液经超滤处理后,截留液中Klason木素,总木素含量增加,灰分,糖及糖醛酸含量有一定程度的降低,酸溶木素含量变化不大,透过液中酸溶木素,灰分,糖及糖醛酸含量增加,而Klason木素及总木素含量降低,同时黑液得到一定程度的浓缩,恒压越滤与普通超滤相比,其所得的截留液中Klason木素,酸溶木素及总木素均比普通超滤高,而灰分,糖及糖醛酸的含量则比普通超滤低,但黑液被稀释。     

Chemical composition of the shell of apricot seeds

The chemical composition of the seed shell of the apricot (Prunus armeniaca) were investigated. Acid and neutral detergent fibres (ADF and NDF) and their fractions—hemicellulose, cellulose and lignin—were determined. The NDF content was about 920 g kg^?1 DM. The concentrations of oils, soluble sugars, pectins, polyphenolic compounds, proteins and mineral elements were also determined. None of these fractions was present at levels higher than 25 g kg^?1 DM. Essential amino acids comprised 38-41% of the total amino acids. Potassium (2.44 g kg^?1) was the most abundant element, followed by calcium (1.15 g kg^?1). Some possible applications for apricot seed shell are considered.     

Agriculture group symposium agriculture and pollution

The digestion of carbohydrates in straw and their substituent acetic and phenolic acids was studied using a slaughter technique. Two goats received non-alkali-treated and alkali-treated straws. The latter treatment increased the total apparent digestibility of cellulose by 56% and of hemicellulose by 110%. The ratio of cellulose to hemicellulose was altered in the rumen. For the non-alkali-treated straw the ratio decreased compared with the feed, whereas it increased for the alkali-treated straw. The ratio was kept almost constant post-rumen for both diets. The composition of the hemicellulose was also altered in the rumen compared with the straws fed. In particular the arabinose content decreased in both diets. Most of the polysaccharide digestion and absorption took place in the rumen. For the alkali-treated straw a hindgut fermentation could also be noted, especially for cellulose. Klason lignin was lost in the rumen but was recovered in the small intestine. Ferulic acid was more readily lost in the rumen than p-coumaric acid. Although acetyl groups were almost absent in the alkali-treated straw, they could still be found in the digesta of the animal. The slaughter technique appears to be a useful method when working with partitioning of digesta in ruminant animals.     

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.     

水稻秸秆纤维素纳米晶须的制备及其表征

为开发水稻秸秆的高附加值应用,采用2,2,6,6-四甲基哌啶-氮-氧化物（TEMPO）体系,以水稻秸秆为原料制备纤维素纳米晶须,并采用傅里叶变换红外光谱仪、扫描电子显微镜、X射线衍射仪等对其进行表征分析。研究结果表明：水稻秸秆主要含有纤维素、半纤维素和木质素,经化学处理后纤维素含量显著提高,而半纤维素和木质素含量有所降低;水稻秸秆横截面呈多孔状,内部及表面均随机分布着大小不等的球状颗粒;化学处理部分去除了非纤维素物质,纤维表面变得相对较光滑;冷冻干燥后的纤维素纳米晶须交织成多层网状,直径为10~25nm,长度为200~400nm;水稻秸秆及其纤维与纤维素纳米晶须的结晶度分别为29.76%,30.28%和40.71%,三者均表现为纤维素Ⅰ的晶体结构。     

嗜碱性木素降解菌降解能力的初步研究

通过比较不同嗜碱细菌对麦草中木素、纤维素和半纤维素的降解率, 并比较不同菌株的产酶及酶活情况, 筛选出了木素降解能力较强, 而纤维素和半纤维素降解能力相对较弱的嗜碱性木素降解菌。在ｐＨ≈１０－４的条件下培养８ｄ 后, 菌株６ 降解了３２－３７％ 的麦草木素, 而纤维素和半纤维素分别降解了２１－４８％ 和２２－６９％ 。这与其产酶情况基本一致, 该菌株的酶活最高, 分别为ＭｎＰ２７１－３０Ｕ／Ｌ和ＬｉＰ４１－９４Ｕ／Ｌ。     

Ration digestibilities and ruminal characteristics in steers fed chickpeas

Twenty-four Holstein steers were used in a 5-d digestion trial to evaluate chickpeas as a substitute for corn and soybean meal. Total mixed diets contained (dry basis) 51% concentrate mix, 33% corn silage, and 16% alfalfa hay. Concentrate mixes contained 0, 50, and 100% chickpeas in place of corn and soybean meal. Ad libitum intakes of DM were not different between diets. Digestibilities of DM, NDF, ADF, hemicellulose, cellulose, lignin, and gross energy were not different among diets. Digestibilities of protein, fat, and ash were greater for steers fed 100% chickpeas than 0% chickpeas. Fecal N was lower and absorbed N was higher for steers fed 100% chickpeas. Ruminal acetate and acetate:propionate ratio were lower and ruminal propionate was higher for all steers fed diets containing chickpeas. Ruminal ammonia and pH were similar for all treatments.     

制取可降解纤维地膜的秸秆纤维特性研究

原料的特性在很大程度上决定了产品的特性及加工工艺,因此对制成可降解纤维地膜的原料秸秆纤维进行物理化学及机械打浆特性研究具有重要意义。本研究采用Leica显微镜测定秸秆纤维形态,SPSS17．0统计分析纤维长宽比,Design-expert6．0．10区组对比分析两种秸秆、纤维间理化及机械打浆特性差异和经机械加工后纤维成...     

Nutrient content of whole cottonseed

The objective of this study was to determine if the nutrient and gossypol contents and in vitro digestibility of 3 types of genetically modified whole cottonseed differed from traditional whole cottonseed. Samples of seed from traditional (no genetic modifications) and genetically modified varieties of cotton grown in 1999 and 2000 were analyzed. Genetic modifications included the insertion of genes to protect cotton from insect pests (Bt), and damage from glyphosate herbicides (RR), and from both (Bt/RR). Year effects were significant for in vitro dry matter (DM) digestibility, gossypol, DM, crude protein (CP), fat, neutral detergent fiber (NDF), acid detergent fiber (ADF), and ash. Higher rainfall resulted in higher CP, fat, and ash and lower NDF and gossypol. There were no differences among seed types for ground or whole seed digestibility, DM, CP, fat, NDF, ADF, ash, lignin, net energy for lactation, amino acids, total fatty acids, or seed index. Overall, the nutrient content and digestibility of varieties of genetically modified seed were similar to that of varieties of traditional whole cottonseed.     

Fractionation and characterization of ball‐milled and enzyme lignins from abaca fibre

An Erratum has been published for this article in Journal of the Science of Food and Agriculture 79(15) 1999, 2122. Ball‐milled and enzyme lignins were produced from abaca fibre via ball milling for 6 days followed by cellulase treatment for 3 days. The crude lignin preparations were fractionated into milled lignin (ML), enzyme lignin (EL), hemicellulose‐rich milled lignin (HRML), and lignin‐rich enzyme lignin (LREL) fractions using a two‐step precipitation method instead of a traditional ether precipitation procedure. The yield and chemical composition of the resulting lignin samples are reported. The ML and EL fractions contained low amounts of associated neutral sugars (2.0–3.3%) and uronic acids (1.4–1.5%), and showed relatively low average molecular weights (2500–2660), while the LREL and HRML fractions contained large amounts of bound polysaccharides (35.6–38.3%), and showed high molecular weights (8800–25000). The four lignin fractions are composed of a large proportion of syringyl units with fewer guaiacyl and p‐hydroxyphenyl units. The ML is mainly composed of β–O–4 ether bonds between the lignin structural units. The less common β–β, β–5 and 5–5′ carbon–carbon linkages are also present in the lignin molecules. It was found that uronic acids and 41–63% of p‐coumaric acids are esterified to lignin in the three lignin‐rich fractions of ML, EL and LREL. This level increased to over 90% in the hemicellulose‐rich fraction of HRML. For ferulic acids, 92–97% were found to be etherified to lignin in the three lignin‐rich fractions of ML, EL and LREL, while in the hemicellulose‐rich fraction of HRML this reduced to only 13%, suggesting that a majority of the ferulic acids are esterified to hemicelluloses or lignin in this fraction. © 1999 Society of Chemical Industry