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Digestibility by sheep of direct cut alfalfa silage made with ozonated cotton stalks
Abstract
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 aim of this study was to evaluate the chemical composition, in vitro DM degradability, ME and OMD of alfalfa-maize silage mixtures in comparison to pure maize and alfalfa silages, and to test the existence of associative effects of ensiling alfalfa forage with whole-crop maize using the in vitro gas production technique. Ensiling alfalfa with whole-crop maize had a significant (p<0.001) effect on chemical composition, pH, in vitro DM degradability, OMD and estimated ME values of mixtures. DM content of the resultant silages significantly increased with increasing proportion of whole-crop maize in the mixtures, whereas the pH value, crude protein (CP), acid detergent fibre (ADF) and ash contents of mixtures decreased due to the dilution effect of whole-crop maize which was low in CP, ADF and ash. The pH values of all alfalfa-maize silage mixtures were at the desired level for quality silage. Gas production of alfalfa-maize silage mixtures at all incubation times except 12 h increased with increasing proportion of whole-crop maize. When alfalfa was mixed with whole-crop maize in the ratio 40:60, ME and OMD values were significantly (p<0.001) higher than other silages. Maximum gas production (Agas) ranged from 65.7 to 78.1 with alfalfa silage showing the lowest maximum gas production. The results obtained in this study clearly showed that maximum gas production increased with increased percentage of whole-crop maize in the silage mixtures (r = 0.940, p<0.001). It was concluded that ensiling alfalfa with whole-crop maize improved the pH. OMD and ME values. However, trials with animals are required to see how these differences in silage mixtures affect animal performance.
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.
The ability of natural silage microflora to degrade and utilize indigenous and extraneous pectic materials during the ensilage of ryegrass was assessed in 2 liter laboratory glass silos. The treatments consisted of ryegrass wilted to 24% (R) and 32% (W) dry matter (DM) and three pectic treatments applied to (R) at approximately 10% of the total DM (R + pectin, R + polygalacturonic acid and R + galacturonic acid). All silages were of a good quality, as judged from visual and analytical evaluation. Pectin, either indigenous or extraneous, was not degraded, or was hardly degraded, by the natural silage microflora. Free galacturonic acid was markedly degraded and utilized, but its fermentation did not result in a higher concentration of preserving acids.
In this study, the effect of stage of maturity of maize (Zea mays L., cultivar ‘Felix’) on site and extent of cell-wall neutral monosaccharide (CWM) digestion in dairy cows receiving diets with ear and husk meal (EHM)-silages was investigated. Ears and husks were harvested at the early, soft and hard dough stages of maturity, respectively, chopped and ensiled. Three diets were formulated to contain (percentage of diet dry matter) EHM-silage (42%), grass hay (39%), soybean meal (17%) and mineral-vitamin mix (2%). Diets containing EHM-silages from the early, soft and hard dough stages of maturity were designated ED, SD and HD, respectively. Three lactating German Friesian cows equipped with ruminai, duodenal and ileal cannulae were used in a 3 × 3 Latin square design to evaluate apparent organic matter (OM) and CWM digestibilities in the whole-tract, and in the rumen, and in the small and the large intestines, respectively. Titanium (IV)-oxide and chromium ethylene diamine-tetra-acetic acid were used as flow markers. In all diets, glucose was more digestible in the whole-tract and in the rumen than xylose, the main hemicellulose constituent. Apparent wholetract digestibilities of OM (ED, 74.6%; SD, 71.8%; HD, 72.1%) and total CWM (ED, 78.1%; SD, 71.7%; HD, 73.7%) were higher with ED compared to SD and HD, but none of these differences were significant. Ruminal characteristics (pH values and NH3-N) were not different among diets (P > 0.10) and indicated similar conditions for rumen microbial CWM fermentation. However, apparent ruminal CWM digestibilities were higher with ED compared with SD and HD, and differences were significant (P < 0.10) for glucose (ED, 72.2%; SD, 59.6%; HD, 61.3%), arabinose (ED, 85.2%; SD, 78.3%; HD, 74.8%) and mannose (ED, 84.1%; SD, 80.4%; HD, 81.3%). Apparent digestibilities in the small intestine (up to 7.6% for glucose with SD) indicated appreciable microbial fermentation in the ileum.
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.
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 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.
The effect of ammonia treatment (4 % on a dry matter (DM) basis) and stage of maturity (3,6 and 12 weeks' regrowth of the grass) on the composition and digestibility by steers of cell wall (CW) monosaccharide residues of coastal Bermuda grass hay (Cynodon dactylon L Pers) is reported in this study. Maturation was associated with a gradual but consistent increase in the content of total and CW glucose and with a slight decrease in the content of matrix minor monosaccharides. The content of the CW non-glucose polysaccharide fraction (NGP) was not affected by maturation. Ammonia treatment exerted a slight solubilising effect on CW components. Monosaccharide residues both in whole hay material and in the CW were equally digestible at the 3-and 6-week stages of maturity, but the digestibility dropped remarkably at 12 weeks of age. Ammonia treatment exerted a notable and positive effect on digestibility of monosaccharides generally, and tended to level off the negative effect of maturation. It is suggested that, in this study, the positive effect of ammonia treatment was mediated mainly via swelling of the CW fibrils, saponification of ester bonds, and loosening of the inner structure of the CW, rather than by solubilisation of CW material.
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.
Digestibility of total and cell wall monosaccharides was studied in sheep with ruminal and duodenal cannulae and fed three wheat straw-based diets: untreated, treated with SO2, treated with SO2 plus cellulase and a fourth diet, which was barley-based. In untreated straw, 90% of total monosaccharides are cell wall bound. Sulfur dioxide treatment solubilized mainly the matrix sugars, reducing their content from 22.1 to 9.76 g/100 g DM in straw. The combined treatment (SO2 plus cellulase) solubilized most of the cell wall sugars so that the most of the cell wall sugars so that the residual cell wall contained only 31% of the total sugars originally present. Treatments increased total monosaccharide digestibility from 63 to 90% and of cell wall monosaccharides from 58 to 84 and 88%. The proportion of digestible monosaccharides degraded in the rumen was increased up to 95% by the treatments. Total monosaccharide digestibility was similar in both treated straws, but degradation of the residual cell wall monosaccharides was somewhat lower in the combined treatment compared with the SO2-treated straw.
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.
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.
Alfalfa was ensiled by the conventional wilting process or as a mixture of 70% fresh alfalfa plus 30% wheat straw treated with SO2. The effects of these silages on the digestibility of monosaccharide constituents of the TMR by dairy cows was examined. Ten cows in early lactation were divided into two groups of 5 that had similar performance data at the onset of the experiment. Cows were fed for ad libitum intake for 28 d a TMR composed of 70% concentrates, 15% alfalfa hay, and 15% silage. The alfalfa silage had lower glucose, xylose, and total carbohydrates than the silage of alfalfa plus wheat straw treated with SO2. Digestibilities of DM (70 to 71%), OM (72%), and total carbohydrate (83%) were similar in the two TMR. The digestibilities of NDF carbohydrate for both TMR were similar. Regardless of treatment, NDF glucose was more digestible than NDF xylose and NDF uronic acid and less digestible than NDF arabinose, galactose, and mannose. The digestibility of total neutral detergent-soluble carbohydrates was 89% in both TMR, but those of neutral detergent-soluble xylose, mannose, and galactose were lower than those of neutral detergent-soluble glucose, arabinose, and pectin.