Dry Digestibility Research Articles

Microbial Delignification with White Rot Fungi Improves Forage Digestibility

Three wild-type white rot fungi and two cellulase-less mutants developed from Phanerochaete chrysosporium K-3 (formerly Sporotrichum pulverulentum) were tested for their ability to delignify grass cell walls and improve biodegradation by rumen microorganisms. Fungal-treated and control stems of Bermuda grass were analyzed for their content of ester- and ether-linked aromatics by using alkali extraction and gas chromatography, for in vitro dry weight digestion and production of volatile fatty acids in in vitro fermentations with mixed ruminal microorganisms, for loss of lignin and other aromatics from specific cell wall types by using microspectrophotometry, and for structural changes before and after in vitro degradation by rumen microorganisms by using transmission electron microscopy. P. chrysosporium K-3 and Ceriporiopsis subvermispora FP 90031-sp produced the greatest losses in lignin and improved the biodegradation of Bermuda grass over that of untreated control substrate. However, C. subvermispora removed the most lignin and significantly improved biodegradation over all other treatments. Phellinus pini RAB-83-19 and cellulase-less mutants 3113 and 85118 developed from P. chrysosporium K-3 did not improve the biodegradation of Bermuda grass lignocellulose. Results indicated that C. subvermispora extensively removed ester-linked p-coumaric and ferulic acids and also removed the greatest amount of non-ester-linked aromatics from plant cell walls. Microscopic observations further indicated that C. subvermispora removed esters from parenchyma cell walls as well as esters and lignin from the more recalcitrant cell walls (i.e., sclerenchyma and vascular tissues). C. subvermispora improved in vitro digestion and volatile fatty acid production by ruminal microorganisms by about 80%, while dry matter loss due to fungi was about 20% greater than loss in untreated control stems. The chemical and structural studies used identified sites of specific fungal attack and suggested mechanisms whereby improvement occurred.

Improvement of the bioconversion and biotransformation efficiencies of the oyster mushroom ( Pleurotus sajor-caju) by supplementation of its rice straw substrate with oil seed cakes

Supplementing the rice straw substrate colonized by the mushroom, Pleurotus sajor-caju, with powdered oil seed cakes (mustard, niger, sunflower, cotton, and soyabean) increased the mushroom yields between 50 and 100%, compared to the unsupplemented substrate. Oil seed cake supplementation also effected an increase in the solubility of the rice straw substrate; there was an increase in the contents of free sugars and amino acids, and a decrease in cellulo-hemicellulosics. Correspondingly, there was also an increase in the activities of carboxymethylcellulase, hemicellulase, and protease. In vitro dry matter enzymatic digestibility measured by two-step enzymatic digestibility of the spent straw (material remaining from the straw substrate, supplemented with the oil seed cakes), indicated a significant increase over that of the spent straw derived from the unsupplemented lot.

Adverse Effects of Pine Needles on Aspects of Digestive Performance in Cattle

Pine needles from ponderosa pine (Pinus ponderosa Lawson) consumed by cows during winter can cause abortions. Our study determined the nutritional impact of pine needles given to steers intraruminally. In Trial 1, 12 steers were given either grass hay alone (CONT), 15% pine needles (15PN), or 30% pine needles (30PN) substituted for hay, as fed basis. In Trial 2, a 4 X 4 Latin square design was used with 4 steers. Treatments were: (1) control-grass hay alone (CONT); (2) grass hay plus 454 g/day of cottonseed meal (CSM); (3) pine needles substituted for 40% (as fed basis) of the hay (PN); and (4) pine needles (40%) plus 454 g/day of CSM (PNCSM). In Trial 1, dry matter intake (DMI), fecal N, and DM digestibility were not affected by either 15PN or 30PN. N intake and N digestibility were reduced (P < 0.07) by 30PN. Fluid dilution rate (FDR) and fluid outflow rate (FOR) were depressed (P = 0.10) by 30PN. Total VFA and ruminal ammonia-N also were depressed by 30PN. In Trial 2, the PN treatment adversely affected DMI, N intake, and all digestibility coefficients, and elevated fecal N. FDR, FOR, and turnover time (TOT) were reduced by 40% PN. Total VFA were increased by PN, while ammonia-N concentrations were reduced. Cottonseed meal had few effects on rumen variables, and there were no CSM X PN interactions. We conclude that pine needles severely affect cattle nutrition, particularly N intake and digestibility and fluid rate of passage. Cottonseed meal, at 1 kg/day, does not ameliorate the adverse effects of pine needles. Fifteen to 30% pine needles in cattle diets appears to be the threshold level for toxic effects on ruminal fermentation.

In saccoDegradability and Apparent Digestibility of Horse Urine Treated Wheat Straw in Sheep and Goats

Abstract Chopped wheat straw was homogeneously mixed with horse urine (1: 1.5; N-content of urine: 5.75 g/l) and stored in airtight plastic containers for 6 months. The straw-silage was of an excellent quality, the crude protein content of urine treated straw was increased from 50 to 99 g and NDF was decreased from 856 to 733 g/kg dry matter. Three sheep and three goats were fed on diets containing untreated (320 g) or urine treated wet wheat straw (800 g) plus concentrate (500 g per animal per day). Rumen in sacco dry matter degradability (DMD) and apparent digestibility (AD) were determined Urine treatment increased significantly the washing loss (from 15.0 to 24.0% of DM) and the potential degradability (from 67.1 to 72.7%). AD of organic matter of wheat straw was increased by urine treatment from 50.4 to 56.0%. There were no significant differences in DMD and AD between sheep and goats.

Yield and quality of leaf protein concentrates from Monochoria hastata (L.) Solms

The yield and composition of leaf biomass and leaf protein concentration (LPC) were determined for Monochoria hastata (L.) Solms, a semi-aquatic weed. The fresh biomass yield was 38–39 tons ha −1 which yielded a total of 1700 kg ha −1 crude protein in three cuts. The various fractions of LPC showed a protein content ranging from 47.4 to 89.4% of dry matter and digestibility ranging from 40.2 to 85.4% of protein. The amino acid content of LPC was found to be nutritionally adequate, except for the sulphur-containing amino acids. The results suggest this plant has promising potential for LPC production.

Enhancement of dry anaerobic batch digestion of the organic fraction of municipal solid waste by an aerobic pretreatment step

The start-up of the dry anaerobic batch digestion by the BIOCEL-concept of the organic fraction of municipal solid waste (MSW) is unbalanced when a methanogenic inoculum (digested sewage sludge) is added to a total solids concentration of 35%. The unbalanced conditions are the result of the rapid degradation of easily-degradable compounds which are present in the organic fraction. Enhancement of the first start-up of the dry batch digestion was tried by applying an aerobic partial-composting step. By this aerobic treatment the easily degradable compounds are removed. After the composting step the anaerobic digestion will be limited by the conversion of the ligno-cellulose part of the organic fraction. It appeared that at least 19·5% of the volatile solids (VS) should be converted during the aerobic composting period before acid formation in the digestion was in balance with the methane formation. This amount of aerobically degraded VS means a 40% loss of potential biogas. The loss of a part of the biogas is a major drawback to the partial composting as a method for enhancing the start-up of the dry anaerobic digestion. A shorter composting period which is combined with another start-up method might be a feasible method to decrease the energy input of the dry digestion process.

The effect of several pH control chemicals on the dry batch digestion of the organic fraction of municipal solid waste

Methane production in dry batch digestion of the organic fraction of municipal solid waste (MSW) was studied as a more complete method for management of MSW than landfilling. For start-up of the dry digestion of the organic fraction of MSW the addition of a methanogenic inoculum is essential. The first start-up of a dry anaerobic digestion batch reactor appeared to be unbalanced when a seed/substrate solids ratio of 0.08 was applied. Higher seed/substrate solids ratios were not employed because the total solids concentration is too low to speak of dry digestion under these conditions. The imbalance resulted in pH values below 6, and organic acid concentrations of 60 g COD (chemical oxygen demand) per liter. At these conditions methane production was negligible. To accelerate the start-up of the dry digestion process, several pH control chemicals were investigated. NaHCO 3 gave the best results when the buffer/ substrate solids ratio amounted to 0.06. The potential methane yield of 80 1 STP of methane per kg of organic fraction was obtained within 6 months. Ca (OH) 2 had a minor effect on the pH. CaCO 3 did not control the pH and inhibited the biogas production. The amount of pH control chemicals which were found to provide optimum pH control resulted in toxic levels of the cations for the methane production. The period required for adaptation of the methane-producing bacteria to these inhibitory cation concentrations limits the benefits of buffer additions during dry digestion.

A simulation study of a continuous two‐phase dry digestion system

In this article a two-phase system for the continuous digestion of wastes with a high solid content is simulated. The studied parameters are: (1) Recirculation from the methanizer to the hydrolyzer, (2) methanizer/hydrolyzer volume ratio, and (3) hydraulic retention time in the hydrolyzer (HRT). Results show that the recirculation ratio is an important operational factor with a large influence on the biodegradation yield, especially at low HRT. Optimum levels of this parameter are established. Some runs of the program have been carried out to test the stability of the system. This has proved to be very stable, especially at low recirculation ratios. The results also show that volume ratio does not appreciably affect the performance of the system, provided it is over a critical value, dictated by the allowable methanizer load.

Determination of Arsenic and Selenium in Whole Fish by Continuous-Flow Hydride Generation Atomic Absorption Spectrophotometry

A combined wet chemical and dry ash digestion and use of a continuous-flow hydride generator coupled with a flame-heated quartz cell enabled the simple, precise, and highly automated atomic absorption determination of arsenic and selenium in tissues of whole fish. Percent relative standard deviation averaged 4% for each element; method detection limits (micrograms/g dry wt) were about 0.06 for arsenic and 0.04 for selenium. Digestion of samples proceeded with little operator attention and without perchloric acid. Analysis for arsenic as As(V) simplified sample preparation but care had to be exercised to avoid interferences from high concentrations of selenium.

Effects of Variety and Particle Size upon Utilization of Fescue Hay by Lactating Dairy Cows and Dairy Heifers

Missouri-96 and Kentucky-31 hays were chopped with a tub grinder containing screens with apertures of 31, 63, or 100mm in diameter and fed to dairy cows or heifers. Particle sizes (geometric mean diameter) were 1218, 1486, and 1933 μm, respectively, for the 31, 63, and 100-mm treatments. In Trial 1, the six treatments were fed ad libitum to 24 lactating cows; concentrate was offered at 1 kg/2kg of milk. Dry matter intake and NDF digestibility were greater for Kentucky-31, but there were no other effects of variety. Particle size did not affect DM intake, DM or fiber digestibility, nitrogen partition, milk yield, or milk fat percentage. Crude protein digestibility was greatest for the 63-mm particle size treatment.In trial 2, the six treatments were fed ad libitum to 24 dairy heifers. Intake was greater for the 31 than for the 100-mm treatment but was unaffected by variety. Variety and particle size did not affect DM digestibility, nitrogen utilization, or daily gain. In this study fescue hay chopped through screens having apertures ranging from 31 to 100mm was without effect on milk yield or composition. Reducing particle size increased intake and nitrogen utilization but not DM or fiber digestibility.

Solid waste fermentation with particular emphasis on potentials for developing countries

Cities of Developing Countries produce around 5000 tons of municipal wastes per day. The treatments used are the dumping in the open, incineration at high costs and low caloric value, aerobic composting fairly suited to dry climates, and anaerobic digestion. In this case 1 ton of the organic fraction of the waste produces 170 m3 of biogas. The available technologies for the anaerobic digestion of municipal wastes are: (1) the conventional completely mixed digester that converts a waste problem into a water problem by using 10 tons of water for 1 ton of waste; (2) the two-step digester; (3) dry digestion, either in landfills where it is spontaneous and lasts 20 to 50 years before complete recovery or in semi-continuous digesters where biogas is recovered in three weeks. At present there exist two examples of dry digestion of municipal wastes, one in France where a 400-m3 digester works with a 35% dry matter substrate and produces 5 m3/m3 of digester per day, and the other in Gent, Belgium, where a pilot plant of 56 m3 fed with the organic fraction of municipal waste, at 35% dry matter, produces 6 m3/m3 digester per day.

Catalytic determination of iodine in biological materials

An analysis schedule for the determination of total iodine in biological materials has been developed. The reaction on which the determination is based is the known catalytic action of iodide on the redox system cerium(IV)-arsenic(III). The dry digestion of the sample, carried out in a nickel crucible, and its preparation are described. The relative standard deviation of the results obtained using the suggested schedule is not more than 2% for amounts up to 60 ng. The analysis schedule was tested for the determination of iodine in various biological materials.

The Hydrolytic step in a dry digestion system

A two-phase anaerobic digestion system is one of the most suitable treatments to dispose of large quantities of dry wastes as, for instance, the organic fraction of municipal solid waste or the bedding straw. In this paper, the hydrolytic step is examined, in a series of 0·3 litre working-volume laboratory reactors. The effects of inoculum, hydraulic retention time (HRT) and temperature are studied. The results show that HRT is one of the most significant parameters in these systems. A Volatile Fatty Acids inhibition model for the hydrolytic step is also proposed, and values of the fitted kinetic constants are given.

Can desert rodents better utilize low quality roughage than their non-desert kindred?

The ability of a desert rodent to exploit dry, low quality plant material and cope with shortage of adequate food, was studied in the Fat jird (Meriones crassus), a Saharo–Arabian gerbil, and compared to that in the Levant vole (Microtus guenteri). The animals were given a restricted amount of fresh carrot (20 g/day) as well as an ad libitum amount of dry roughage, of either high or low quality. Six animals of each species were used in each trial. When tested on alfalfa hay (Medicago sativa), a high quality roughage (25% fibre), the gross energy intake of the Fat jird amounted to only 43% of the value recorded in the Levant vole tested on the same diet. Apparent digestibility of this high quality roughage amounted to about 69% equally in both species. The oxygen consumption of the Fat jird, however, amounted to only 0·430 ± 0·08 litres O2/kg0·75/h, 72% of the value recorded in the vole. When tested on low quality roughage, dry Rhodes grass (Chloris gayana, 30% fibre), apparent digestibility and rate of oxygen consumption in the Fat jird were maintained at levels similar to those recorded when on alfalfa hay. In the Levant vole apparent digestibility dropped to 49% and oxygen consumption to 0·600 ± 0·12 litres O2/kg0·75/h. A high retention time of food in the gastrointestinal tract, mainly in the caecum, of the Fat jird, as well as a high rate of volatile fatty acid absorption from its in situ perfused colon, are suggested to be the major factors in lending the Fat jird its efficient digestive capacities. Both these characteristics are less pronounced in the Levant vole. It is concluded that a low rate of energy metabolism as well as a higher capacity to digest dry plant materials help the Fat jird cope with the shortage of food that is characteristic of most desert habitats.

White-rot fungal growth on sugarcane lignocellulosic residue

Twelve white-rot fungi were grown in solid state culture on sugarcane chips previously fermented by yeast employing the EX-FERM process. The lignocellulosic sugarcane residue had 12.5% permanganate lignin and 81.3% holocellulose. After 5 to 6 weeks at 20° C, all fungi produced a solid residue which had a lower in vitro dry matter enzymatic digestibility than the original bagasse, with the exception of Coriolus versicolor which showed a slight increase of 0.6 units. Four fungi produced a residue with higher soluble solids than the original sample. Lignin losses were rather similar for all fungi tested, an average value of 38.64% of the original value was obtained. About the same amount of hemicellulose was degreaded, 32.22%. Most fungi showed a preference for hemicellulose hydrolysis over cellulose degradation. The two fungi that showed greater cellulolytic activity were Sporotrichum pulverulentum and Dichomitus squalens. No appreciable dry matter losses were detected for Agrocybe aergerita and Flammulina velutipes.

Dry digestion of crop wastes: Studies on dry anaerobic digestion with agricultural wastes

This paper reports the requirements for batch dry-fermentation with agricultural wastes. The optimum initial solids content is 25–30%, with ratios of rice straw to manure (on a dry matter basis) of 2 or 1:1. The inoculum should be over 30% by volume. In the course of the fermentation, when biogas production rate is falling, two additions of inoculum and fresh pig manure lengthen the duration of a biogas production rate of above 0·3 m 3 m −3 day −1, o enhance the total biogas volume and to promote the degradation and utilization of the raw material. This process of dry-fermentation with agricultural wastes gives relatively high total biogas yield, biogas production rate, and degradation rate of raw materials and needs a simple routine management. NH 4HCO 3 can substitute for manure to mix with straw, as well as the nitrogen source, to give similar results.

Biological conversion of paddy straw into feed

Five cellulolytic non-toxic fungi were screened for ability to improve the nutritive value of paddy straw by solid substrate fermentation. Pleurotus ostreatus and Sporotrichum pulverulentum significantly utilized cell wall constituents and increased in vitro dry matter rumen digestibility of paddy straw (IVDRD). The effects of various physical parameters (moisture, temperature, incubation period), nitrogen source and level on the fermentation of paddy straw were studied. Paddy straw containing 50 ml water/10 g straw and fermented either with P. ostreatus or S. pulverulentum for 30 days at 30°C and 40°C, respectively, significantly degraded cellulose and lignin and increased the IVDRD to 53·24% and 51·62%. Nitrogen supplementation in the form of NH 4 Cl at 0·08% was found to be optimum for P. ostreatus and S. pulverulentum, respectively, and the crude protein of fermented straw increased to 9·62% and 9·00% and IVDRD to 60·24% and 59·35%, respectively, within 15 days.

Biodelignification of Lemon Grass and Citronella Bagasse by White-Rot Fungi

Twelve white-rot fungi were grown in solid-state culture on lemon grass (Cymbopogon citratus) and citronella (Cymbopogon winterianus) bagasse. The two lignocellulosic substrates had 11% permanganate lignin and a holocellulose fraction of 58%. After 5 to 6 weeks at 20 degrees C, nine fungi produced a solid residue from lemon grass with a higher in vitro dry matter enzyme digestibility than the original bagasse; seven did the same for citronella. The best fungus for both substrates was Bondarzewia berkeleyi; it increased the in vitro dry matter enzyme digestibility to 22 and 24% for lemon grass and citronella, respectively. The increases were correlated with weight loss and lignin loss. All fungi decreased lignin contents: 36% of the original value for lemon grass and 28% for citronella. Practically all fungi showed a preference for hemicellulose over cellulose.

NifV-dependent, low-molecular-weight factor required for in vitro synthesis of iron-molybdenum cofactor of nitrogenase.

The molybdate- and ATP-dependent in vitro synthesis of the iron-molybdenum cofactor of nitrogenase requires a low-molecular-weight factor. The factor is present in extracts of nitrogen fixation-derepressed cultures of Klebsiella pneumoniae and Azotobacter vinelandii, but not in extracts of repressed cultures of these bacteria. Analysis of K. pneumoniae Nif mutants has indicated that the nifV gene product is the only nif protein (besides nifA) necessary for the synthesis and accumulation of the factor. The factor is stable to oxygen, temperatures below 120 degrees C, and extremely acidic and basic conditions. The activity of the factor was completely destroyed by dry ashing or digestion with sulfuric acid. The factor has been partially purified by filtration through an Amicon PM-10 DIAFLO membrane and chromatography on DEAE-cellulose, hydroxylapatite, silica gel, and Sephadex G-25.

Aqueous ammonia treatment of wheat straw: Voluntary intake and digestibility in cattle

Three experiments were conducted using yearling cattle weighing 235–349 kg with straw treated with aqueous ammonia (ca. 30 g NH 3 per kg straw) in plastic covered stacks. In all experiments ammoniation approximately doubled the nitrogen (N) content of straws and increased straw intake and digestibility. The chromic oxide marker technique was used to determine digestibility. In Experiment 1, daily intakes of straw dry matter (DM) and digestibility of the organic matter (OMD) of untreated and ammoniated wheat straws (cultivar ‘Bounty’) at 4.4 and 5.5 kg, and 0.43 and 0.55, respectively, were greater than those of barley straw (mixture of 3 cultivars) at 4.2 and 4.9 kg, and 0.40 and 0.50, respectively. A soya bean meal supplement had no effect on intake or digestibility of untreated straws. In Experiment 2, daily DM intake and OMD of untreated, wheat straw (‘Armada’) and the same straw treated with aqueous ammonia in a plastic covered stack or anhydrous ammonia in an “Andashstra-verter” oven were 4.3, 4.7 and 4.8 kg and 0.44, 0.50 and 0.55, respectively. In a third experiment there were significant differences in intake, but not digestibility, between straws of three wheat cultivars (‘Avalon’, ‘Flanders’ and ‘Armada’) before and after ammoniation. It is concluded that the effect of treatment of straw with aqueous ammonia by the stack method on the feeding value of straw was more variable than expected and may be related to differences between cultivars.