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Ozonated cotton stalks as a silage additive: Digestion of total and cell wall monosaccharide constituents of lucerne based dairy cows rations
Abstract
Lucerne was ensiled either by the conventional wilting process (WL) or as a mixture of 80% fresh lucerne + 20% ozonated cotton stalks (L + OCS), and the effect of feeding these silages to dairy cows on performance and on the digestibility of ration carbohydrate constituents was examined.Ten cows in mid-lactation were divided into two equal groups with similar performance data at the onset of the experiment, and fed ad libitum for 28 days total mixed rations composed of 70% concentrate, 15% lucerne hay and 15% of either WL silage or L + OCS silage.Average daily milk yields during the experimental period were 27.1 and 27.6 kg in the WL and L + OCS groups, respectively, and the L + OCS cows gained higher body weight. Milk composition was similar in both treatments.The WL silage had a lower content of neutral detergent soluble (NDS) glucose, neutral detergent fibre (NDF) glucose and NDF xylose, and a higher content of arabinose, galactose and mannose than L + OCS silage.Carbohydrate digestibility was 83 and 85% in the WL and L + OCS rations, respectively.NDF digestibility was similar (45.0%) in both rations; however, digestion of NDF glucose, xylose and total polysaccharides was slightly higher in the L + OCS group than in the WL ration.In both rations, NDF glucose was more digestible than NDF xylose and NDF uronic acid and less digestible than NDF arabinose, galactose and mannose.Digestibility of total NDS carbohydrate was 89% in WL ration and 91% in L + OCS ration, and in both groups, digestion of NDS mannose and galactose was lower than that of NDS glucose, arabinose and pectin.Data of this study indicate that a direct-cut and ensiled lucerne silage made of L + OCS is equivalent to lucerne haylage as a component in lactating cow rations.
... The degradation of monomeric cell-wall sugars has been studied with various materials consisting of different cell-wall types (Ben-Ghedalia and Miron, 1984;Miron and Ben-Ghedalia, 1995;Titgemeyer et al., 1991). With these studies the cell-wall sugars, glucose and xylose, are usually reported to be less digestible (at the ruminal or total tract level) while arabinose and galactose are relatively more digestible, which is in agreement with what was found in the present experiments. ...
Two experiments were conducted to investigate the degradation of cell-wall sugars from soya bean meal (in situ), and soya bean endosperm and hulls (in vitro). Soya bean meal, soya bean endosperm, and soya bean hulls were extracted with different chemicals to obtain the cell-wall fraction. Soya bean meal cell walls were incubated in the rumen of a fistulated cow. The individual cell-wall sugars were degraded at different rates: galactose (13.6% h−1), arabinose (7.8% h−1), uronic acids (5.1% h−1), xylose (3.5% h−1) and glucose (3.2% h−1). Microscopic evaluation of the cell walls and degraded material revealed the presence of two cell wall types, with distinctly different degradation characteristics: one originating from the hull (thick, slowly degraded) and one from the endosperm (thin, rapidly degraded). Furthermore, the cell-wall sugar composition of endosperm and hull cell walls was different, most markedly for galactose (281 vs. 12gkg−1) and glucose (132 vs. 508gkg−1). The degradation of endosperm and hull cell walls was measured in vitro by use of in vitro cumulative gas production. Degradation rates of the individual cell-wall sugars for hull cell walls were similar (ranging from 2.4% to 4.6% h−1). For endosperm cell walls, the degradation rates of the individual sugars were different but with the same ranking as in the in situ experiment (ranging from 20.9% to 7.0% h−1). It was concluded that for soya bean meal cell walls, the cell-wall sugar degradation pattern is influenced by the presence of two cell-wall types (hull and endosperm cell-wall), which differ in their rate of degradation and sugar composition. The difference in cell-wall sugar degradation pattern between hull and endosperm cell walls is likely to be caused by a combined effect of particle size and cell-wall thickness.
Alfalfa was ensiled either by conventional wilting (WA) or as a mixture with 20% (DM) ozonated cotton stalks (A + OCS), and the digestibility of the silage carbohydrate constituents was examined in sheep. The WA silage had a lower content of glucose, xylose, and total carbohydrates and a slightly higher content of arabinose, galactose and mannose than the A + OCS silage. Stomachs and whole tract carbohydrate digestibility was 52% and 63%, respectively, in both silages. Digestibility of neutral detergent fiber (NDF) glucose and xylose was slightly higher and that of NDF-arabinose, galactose and mannose slightly lower, in the sheep fed A + OCS vs. those fed WA.Digestibility of total NDF monosaccharide components in WA and A + OCS silages were 55% and 57%, respectively, of which 90% were digested in the fore-stomachs. In both silages, NDF-glucose was more digestible than NDF-xylose and NDF-uronic acid, and less digestible than NDF-arabinose and NDF-mannose.Results of this study indicate that a direct-cut and ensiled alfalfa silage made with 20% (DM) OCS is comparable with WA in its potential to supply ruminants with digestible carbohydrates.
The objective of this experiment was to study the effects of level of intake and proportion of forage in the diet on site and extent of digestion of plant cell wall monomeric components (phenolics, neutral sugars) by sheep. Four Suffolk wethers (65 kg) with ruminal and duodenal cannulas were fed diets containing 75% (75A) or 25% (25A) alfalfa hay at two levels of intake, 1,700 (high intake, HI) or 1,100 (low intake, LI) g DM/d in a 4 X 4 latin-square design with a 2 X 2 factorial arrangement of treatments. The remainder of the diet consisted primarily of ground corn. Wethers had lower (P less than .05) total tract NDF and ADF digestibilities when fed 75A or at HI. An intake X forage level interaction (P less than .05) was noted for non-core lignin ferulic acid (FA) total tract disappearance, with wethers at LI having the highest, 25A-HI having the lowest, and 75A-HI having an intermediate FA disappearance. Wethers fed at LI had higher (P less than .05) total tract disappearance of non-core lignin p-coumaric acid (PCA). Wethers fed 75A had greater (P less than .05) total tract disappearances of core lignin vanillic acid (VA) and vanillin (VAN). Total tract digestibilities of the neutral monosaccharides glucose (GLC), xylose (XYL), arabinose (ARA) and galactose (GAL) were greater (P less than .05) for LI vs HI treatments. Wethers consuming 75A had greater (P less than .05) total tract ARA and GAL digestibilities, whereas wethers fed 25A had greater (P less than .05) total tract digestibilities of GLC and mannose (MAN). Diet composition and level of intake appear to influence site and extent of digestion of cell wall monomeric components.
Lambs of the Assaf dairy breed were assigned at 23–24 kg liveweight to one of three nutritional treatments: I, a high-energy concentrate mixture (CD); II, a diet in which 40% of the concentrate was replaced by a 1:1 mixture of untreated cotton stalks (CS) and poultry litter (UT-CS); III, as II, but the CS were treated with ozone gas (O3-TCS). The diets were fed ad libitum for 42–65 days until the lambs reached approximately 40 kg liveweight. The average daily liveweight gains were 226 g, 298 g and 395 g for the UT-CS, O3-TCS and CD rations, respectively. The better performance of the O3-TCS group of lambs, as compared with the UT-CS group, was the result of a 9.6% higher feed intake and 16.2% more efficient utilization of the diet.It was calculated that a 1:1 mixture of O3-treated CS and poultry litter could save 18.2% of the concentrates needed to raise lambs to 41.2 kg liveweight.
The effect or effects of varying levels of alkali (NaOH) or oxidant (NaClO2) on composition of alfalfa and in situ disappearance of OM, NDF, and NDF monosaccharides were determined. Three field replicates of fourth-cutting alfalfa (early and late bud) were treated at harvest with 0, 2, 4, 6, or 8 g of NaOH or NaClO2/100 g of herbage DM. Herbage was hand cut (15-cm stubble height), hand sprayed, and artificially dried (50°C). Alkali treatment linearly increased NDF, crude hemicellulose, and NDF N but decreased CP. Quantity or composition of lignin was not altered consistently by NaOH treatment. Glucose concentration was lowered as a result of NaOH treatment. Oxidant linearly decreased NDF, lignin, ADF N, CP, and concentration of lignin nitrobenzene oxidation products. Alkali and oxidant treatment linearly increased in situ disappearance of OM and NDR NaOH tended to increase xylose disappearance, whereas NaClO2 tended to increase glucose disappearance. Both treatments increased arabinose disappearance. Alkali and oxidant had divergent effects on fiber and lignin composition, yet both types of treatment increased potential disappearance of NDF. Disappearance of NDF in chemically treated alfalfa may not be related to quantity or composition of lignin.
Preservation of crop quality, DM, and energy in the silo requires that plant respiration, plant proteolytic activity, clostridial activity, and aerobic microbial growth be limited. A critical mechanism for limiting these processes is quick attainment and maintenance of anaerobic conditions in the silo. If the crop is wilted to greater than 55% DM, fermentation of the crop plays a minor role in making quality silage. For wetter crops, a rapid decline in pH is essential.Dropping pH by fermentation requires an anaerobic environment, adequate substrate, and sufficient numbers of lactic acid bacteria. The substrate required for good fermentation is dependent on the crop, increasing with buffering capacity and moisture content. Approximately 108 lactic acid bacteria per gram of crop are required before a noticeable drop in pH occurs. Because this concentration is much greater than that supplied by inoculants, the most important characteristic for an inoculant is fast growth rate in the silo environment. Also, an inoculant's success depends on adequate substrate and its population relative to the natural one. Dropping pH by acids effects an immediate pH change, which is beneficial in preserving protein nitrogen. However, this advantage must be balanced against its cost and safety in handling.
The digestibility of cell wall (CW) monosaccharides of diets containing as 50 % of their OM, untreated, sodium hydroxide and ozone-treated cotton straw (CS), was studied in sheep cannulated in the rumen and at the duodenum with simple cannulae.
CS contributed the major part of the dietary cell-wall glucose, xylose and uronic acid in the three diets. The digestibility of the diets' CW glucose was 38·2, 66·6 and 50·2 % for the untreated, ozone and NaOH-treated CS-diets, respectively. Ozone and NaOH treatments significantly increased the digestibility of cotton straw CW glucose by 108 and 42%, respectively. The highest digestibility of CW xylose in the whole diet was obtained in the NaOH treatment: 43·4% as compared with 19·1 and 31·2% in the untreated and ozone-treated diets. The calculated values of CW xylose digestibility in CS were lower than those of CW glucose. Ozone remarkably increased the degradation of CW uronic acids. The calculated value for ozonated CS was 68·7%, 4·09 and 1·47 times higher than in the untreated and NaOH-treated CS.
Irrespective of diet, the digestibilities of the minor CW sugars, i.e. arabinose, galactose and mannose, were high, and their degradation was largely completed in the rumen. The contribution of the hindgut flora was expressed mainly in degrading the residues of the potentially digestible CW glucose and CW xylose.
The digestibility values of ADF-cellulose and those of CW glucose were compatible, whereas those of hemicellulose (determined as NDF-ADF) and CW non-glucose polysaccharides (NGP) were clearly different. The digestibility of NGP was 16·8, 36·6 and 43·2% for the untreated, ozone and NaOH-treated CS, respectively. It is suggested that those values more closely represent the digestibility of the ‘true hemicellulose’ fraction.
The effect on fermentation patterns and silage properties of ensiling alfalfa (A) with ozonated cotton stalks (OCS), added at 10, 20, and 30% of dry matter, was explored in laboratory silos. Silos were opened after 90 days, and the silages were analyzed. DM loss was highest for the untreated A silage (14.6%). DM loss in the A + OCS silages was 1-4%, much lower than in the wilted A silage (7.4%). Reducing sugars and fructose were the major carbohydrates fermented; pectin uronic acid (PUA) proved resistant to 90 days of fermentation. OCS is acidic (pH 2); therefore, the pH of the 10% OCS + A mixture dropped to 5.2 immediately at mixing. This allowed a fermentation to proceed, as reflected from sugar fermentation and lactic acid production (3.55%). At 20 and 30% OCS + A mixtures, pH decreased immediately to 4.47 and 4.26, respectively, so the fermentation was partly or completely inhibited. Protein, extensively degraded in the A silage, was preserved in the A + 30% OCS silage. Wilted A + 20% OCS silages were comparable in protecting the alfalfa forage protein.
Fermentation patterns of lucerne silages were studied in laboratory silos. The treatments consisted of: (a) fresh (200 g kg>−l DM) lucerne, ensiled without any treatment (L); (b) lucerne wilted to 525 g kg−1 DM prior to ensilage (WL); (c) fresh lucerne + cotton stalks at a ratio of 60:40 on a dry matter (DM) basis (L + CS); and (d) fresh lucerne + ozone-treated cotton stalks at the same ratio as above (L+O3). Silos were opened after 90 days and the silages analysed. The highest DM loss was found in the L silage (14·7%), whereas in the L+O3 silage DM loss was practically nil. Both wilting and the addition of untreated cotton stalks proved to be effective in reducing DM losses during fermentation. The production of lactic acid and volatile organic acids in the L+ O3 and WL silages was lower than in the L and L+CS silages. The poorest ability to preserve forage protein was found in the L silage, in which only 28 % of the protein was recovered after 90 days. The greatest ability to preserve protein was found in the L+O3 silage, in which 78 % of the protein was maintained. Ammonia production followed generally similar patterns. Amino acids underwent extensive degradation in the L silage. Recovery of amino acids in the WL silage was in the range 69–93 %, and in the L + O3 silage it was almost complete. Ozonated CS proved to be a good silage additive with respect to energy and protein preservation. Its future use in the field would allow direct ensilage of fresh leguminous material immediately after harvest, producing a high quality silage.
Cotton straw (CS) was treated with ozone or sodium hydroxide, and the effect of treatments on the organic acid and monosaccharide composition and on the chromat-ographic characteristics of alkali lignin was studied. The concentrations of formic and acetic acids in the ozonised CS were 3.98 and 1.36 g 100 g−1 organic matter (OM) respectively. Oxalic acid was not detected. A high content of uronic acids (9.78 g 100 g−1 OM) was found in CS. The overall decrease in total monosaccharides in the ozonated CS was very small (5%) with the matrix constituents being principally affected. The 8% sodium hydroxide treatment exerted a very limited effect on the composition of CS cell walls. Ozonation increased the content of soluble carbohydrates from 9.2 to 21.8%; this was contributed mainly by the hemicellulose fraction. Alkali lignin was extracted from CS and was fractionated by gel chromatography. The elution pattern of alkali lignin was very similar for the treated and untreated materials. The three peaks coincided at an average mol. wt of 40 000, as judged from the use of dextran standards.
Chemical and biological delignification methods were used to investigate the relationship between the concentration and composition of lignin and degradation of forage cell walls. Stem material from lucerne (Medicago sativa L), smooth bromegrass (Bromus inermis Leyss) and maize (Zea mays L) stalks was treated with alkaline hydrogen peroxide, potassium permanganate, sodium chlorite, sodium hydroxide, nitrobenzene, and the lignolytic fungus Phanerochaete chrysosporium. Klason lignin and esterified and etherified phenolic acids were delermined. Cell wall neutral sugar and uronic acid composition and the extent of in-vitro degradability were measured. Chemical delignification generally removed lignin. but the fungal treatment resulted in the removal of more polysaccharide than lignin. The concentrations of esterfied and etherified p-coumaric and ferulic acids were generally reduced in treated cell walls; chlorite treatment preferentially removing p-coumaric acid whereas nitrobenzene treatment removed more ferulic acid. Syringyl moieties were completely removed from the core lignin polymer by nitrobenzene treatment of forage stems. Alkaline hydrogen peroxide and nitrobenzene were generally the most effective delignification treatments for improving polysaccharide degradability, with the grass species responding similarly to delignification whereas lucerne was somewhat less responsive. Fungal delignification, under these experimental conditions, did not improve cell wall degradability of these forages. Multiple regression and covariate analyses indicated that the lignin components measured were not powerful predictors of cell wall degradability. Neither the concentration nor the composition of the lignin fractions was consistently correlated with degradation. This lack of effect was attributed to the more generalised disruption of the cell wall matrix structure by delignification treatments.
Lucerne (alfalfa) was harvested at different stages of maturity and the plants classified according to a phenological scale. The main class was separated into anatomical parts and analysed for content of extractives and crude protein and in-vitro degradability. Whole crop samples were also analysed for polysaccharide residues, Klason lignin and in-vitro degradability of crude protein and polysaccharide residues. The composition of the plant changed during maturation with an increase of the stem fraction from 18.5% to 50.7% of dry matter and a corresponding decrease in the leaf fraction from 72.9% to 18.4% of dry matter. The leaf fraction changed least in content of extractives and crude protein and in-vitro degradability while in the stems all these paramaters decreased radically. Chemical analysis of residues after incubation with rumen liquor in vitro of whole crop samples revealed that the degradability of crude protein declined from about 90% to about 80% and of non-starch polysaccharides from about 90% to about 60% during maturation. Xylose was the least degradable polysaccharide residue at all harvests. Xylose residues also showed the greatest decrease in degradability during growth. A comparison showed that stage of development and harvest date were of practically equal value as predictor of crude protein content in lucerne.
A simple and rapid method is described for the preparation of alditol acetates from monosaccharides. It can be performed in a single tube without transfers or evaporations. Monosaccharides are reduced with sodium borohydride in dimethyl sulphoxide and the resulting alditols acetylated using 1-methylimidazole as the catalyst. Removal of borate is unnecessary and acetylation is complete in 10 min at room temperature. Monosaccharides are quantitatively reduced and acetylated by this procedure. The alditol acetates are completely separated by glass-capillary, gas-liquid chromatography on Silar 10C. The method has been applied to the analysis of monosaccharides in acid hydrolysates of a plant cell-wall.
Four Holstein heifers were used in a 4 X 4 Latin square design to measure total tract digestion of cell wall components from diets based on alfalfa haylage and alkaline hydrogen peroxide-treated oat hulls. Diets contained 90% forage and 10% concentrate. Treatments were diets containing 90, 70, 50, or 30% alfalfa haylage with treated oat hulls supplying the remainder of the forage portion. Total tract digestion of cell wall-associated uronic acids, arabinose, galactose, mannose, rhamnose, and lignin were not affected by forage source. Digestibilities of cell wall glucose and xylose increased with increasing level of dietary treated oat hulls, reflecting the positive effect of alkaline hydrogen peroxide treatment on cell wall digestion. Cellulose (ADF minus acid detergent lignin) digestibilities were similar to those for cell wall glucose, whereas hemicellulose (NDF minus ADF) digestibilities were similar to those for cell wall arabinose plus xylose. Low digestibilities of alfalfa cell wall xylose indicate that some cell wall structure inhibits the degradation of alfalfa xylans. Low degradabilities of core lignin, esterified p-coumaric acid, and esterified acetyl groups suggest that these components may be involved primarily in depressing fermentation of cell wall polysaccharides.
There is a need to standardize the NDF procedure. Procedures have varied because of the use of different amylases in attempts to remove starch interference. The original Bacillus subtilis enzyme Type IIIA (XIA) no longer is available and has been replaced by a less effective enzyme. For fiber work, a new enzyme has received AOAC approval and is rapidly displacing other amylases in analytical work. This enzyme is available from Sigma (Number A3306; Sigma Chemical Co., St. Louis, MO). The original publications for NDF and ADF (43, 53) and the Agricultural Handbook 379 (14) are obsolete and of historical interest only. Up to date procedures should be followed. Triethylene glycol has replaced 2-ethoxyethanol because of reported toxicity. Considerable development in regard to fiber methods has occurred over the past 5 yr because of a redefinition of dietary fiber for man and monogastric animals that includes lignin and all polysaccharides resistant to mammalian digestive enzymes. In addition to NDF, new improved methods for total dietary fiber and nonstarch polysaccharides including pectin and beta-glucans now are available. The latter are also of interest in rumen fermentation. Unlike starch, their fermentations are like that of cellulose but faster and yield no lactic acid. Physical and biological properties of carbohydrate fractions are more important than their intrinsic composition.
A new method for determination of uronic acids with meta-hydroxydiphenyl is introduced. It is simpler, quicker, more sensitive, and more specific than other methods, and it needs lesser amounts of fluid. It is recommended for determination of acid mucopolysaccharides in biological materials.
1. Steers, equipped with simple rumen cannulas, were given diets of approximately equal parts of rolled barley and straw supplemented with urea. The diets provided sufficientestimated rumen degradable nitrogen (RDN: RDN: metabolizable energy values of 1:3) to maintain maximum microbial synthesis. In some experiments Na 2 ³⁵ SO 4 was introduced into the rumen to label microbial protein.
2. Rumen digesta samples were taken before feeding and mixed rumen bacteria were separated from the solid (solid-associated bacteria; SAB) and liquid (liquid-associated bacteria; LAB) fractions of digesta. The most effective method of removing SAB from the fibre was a combination of homogenizing and pummelling. This process did not affect the physical form or chemical composition of the bacteria.
3. Samples of SAB contained significantly ( P ≤ at least 0·05) less ash, total N, RNA and diaminopimelic acid (DAP) and significantly ( P ≤ 0·01) more lipid than samples of LAB. Concentrations (g/kg dry matter) of ash, total N, RNA, DAP and lipid in SAB were approximately 87, 70, 35, 2.2 and 245 respectively. Corresponding values for LAB were 157, 80, 50, 3.8 and 124 respectively.
4. RNA-N: total N and DAP-N: total N values in SAB were significantly lower than those in LAB ( P ≤ 0·05 and 0·02 respectively). ³⁵ S: totalN values were similar in both groups of bacteria. The importance of differences in constituent: total N values in the two groups of bacteria in relation to their use as indices of microbial protein synthesis is discussed.
The effect of dietary starch on the digestibility of total and cell wall (CW) monosaccharides of alfalfa hay, was examined in sheep equipped with rumen and duodenal cannulas. The experiment consisted of two treatments. In one of them the sheep received 803 g dry matter (DM) of alfalfa hay (A), and in the second, 242 g DM alfalfa hay + 553 g of a purified starchy concentrate mixture (A + conct ). Rumen volume was not significantly different between treatments, but the mean retention time of markers in the rumen was shorter, and their rate of passage was faster in the A treatment than in the A + conct treatment. The overall digestibility of total CWs and CW constituents was not depressed in the A + conct treatment, the values for total CW being: 58.2 and 58.9% for the A and A + conct treatments, respectively. However, the digestion of CW monosaccharides in the rumen of the A + conct sheep was reduced despite the 100% longer retention time of particles in the rumen. The complimentary digestion of the potentially digestible CW monosacharides has been completed in the hindgut. The digestibility of CW glucose was higher (72%) than that of xylose (57%) in both treatments. CW glucuronic acid was the least digestible constituent (40%). Soluble uronic acids, representing the pectic material, were highly digestible (86.5% in A), but this was reduced to 80.3 in the A + conct treatment.
Ozone treated cotton stalks as a component of a ration for growing lambs Statistical Analysis Systems Institute Inc., 1985. SAS User's Guide: Statistics, Version 5 Edition Digestion of cell wall components by dairy heifers fed rations based on lucerne and chemically treated oat hulls
- R Solomon
- J Miron
- A Rubinstein
- D And Ben-Ghedalia
- Nc Gary
- E C Titgemeyer
- M G Cameron
- L D Bourquin
- Fahey
- G C Jr
Solomon, R., Miron, J., Rubinstein, A. and Ben-Ghedalia, D., 1992. Ozone treated cotton stalks as a component of a ration for growing lambs. Anim. Feed Sci. Technol., 37: 185-l 92. Statistical Analysis Systems Institute Inc., 1985. SAS User's Guide: Statistics, Version 5 Edition. Sta-tistical Analysis Systems Institute Inc., Gary, NC. Titgemeyer, E.C., Cameron, M.G., Bourquin, L.D. and Fahey, Jr., G.C., 199 1. Digestion of cell wall components by dairy heifers fed rations based on lucerne and chemically treated oat hulls. J. Dairy Sci., 74: 1026-1037.