Studies on untreated and urea-treated rice straw from three cultivation seasons: 2. Evaluation of straw quality through in vitro gas production and in sacco degradation measurements

Untreated and urea-treated straw and straw fractions of seven rice varieties from three cultivation seasons have been evaluated on their DM, OM loss and degradation characteristics from in sacco disappearance and in vitro gas production measurements. Drying temperatures from 45°C to 100°C did not seem to influence the degradability of urea-treated rice straw, whereas urea-treated straw dried at freezing temperatures (−35°C) gave slightly higher degradability than higher temperatures. Untreated early season rice straw showed higher degradability than straw of middle and later season rice. There was a significant increase in the degradation of straw after urea treatment, and greatest for late and middle season rice straw. On average, urea-treatment of rice straw increased the DM and OM in sacco losses after 48 h of incubation (48 h) by 24.0% and 30.7%, respectively. In order to study the kinetics of the degradation of fibre fractions, the disappearance in sacco was also estimated for the loss of hemicellulose, cellulose and extractable biogenic silica (EBSi). There was a great variation in the content of silica between varieties. Rice straw degradation seemed to be related to the biogenic silica content (acid detergent insoluble silica (ADISi)). Urea treatment increased the extraction of biogenic silica and hence increased the degradation of hemicellulose and cellulose. The improvement in sacco disappearance of cellulose due to urea treatment was 36.8%, 19.5% and 5.3% for late, middle, and early rice straw, respectively. The degradability was higher for the stem than for the leaf blades and leaf sheaths. The response to urea treatment, however, was higher for leaf sheaths and leaf blades than for the stems, evening out differences in degradability. Urea treatment tended to increase the production of acetic acid whereas there was no effect on propionic and butyric acid production.     

Processing and nutritive evaluation of broiler litter as livestock feed

Broiler litter was deep stacked at 30 and 40% moisture or ensiled at 40% moisture for 6 weeks in quadruplicate and subsequently evaluated for changes in chemical composition, pathogenic microbial load and in vitro dry matter degradability (IVDMD). A metabolism trial was conducted with lambs, in which a low-protein basal diet supplemented with litter, deep stacked at 30% and 40% moisture for 6 weeks or ensiled were compared with an isocaloric, isonitrogenous soybean meal supplemented diet. The maximum stack temperature of 65°C (irrespective of moisture level) was attained on day 7 at 45 cm depth and 60.5°C on day 10 at 80 cm depth, which eliminated coliforms. Increases in lactic and acetic acids were recorded with increase in moisture levels and advancement of stacking period. A small increase in crude protein (CP) content was associated with considerable declines in organic matter (OM), cellulose, neutral detergent fiber (NDF) and hemicellulose in deep-stacked litters. The apparent digestibility of nutrients and N-retention in the litter-supplemented diets were similar to those of the soybean meal supplemented diet. It is concluded that by deep stacking at 30 or 40% moisture, or ensiling, the litter was rendered free of pathogens and could be incorporated in the diet of livestock without adversely affecting digestibility of fiber and efficiency of N utilization.     

Effect of high-pressure steam treatment on chemical composition and digestibility in vitro of roughages

Effect of high-pressure steam (5, 7 and 9 kg cm^?2 for 30 and 60 min) on chemical composition and digestibility in vitro of sugarcane bagasse, paddy straw and sorghum straw was studied. The treatment brought about significant falls in the neutral detergent fibre (NDF), specifically the hemicellulose content, and in pH. Soluble carbohydrates and volatile acids (VA) increased with treatment, while acid detergent fibre (ADF) remained constant. The increments in true dry-matter digestibility in vitro (IVTDMD) compared to untreated were 23–64% (sugarcane bagasse), 19–36% (paddy straw) and 31–42% (sorghum straw) with increasing steam pressures and period. The digestibility of cell-wall constituents (CWC) improved with steam treatment in all three roughages. The dry-matter losses resulting from the treatment were 0.9–20%, 17–39% and 1–22% for sugarcane bagasse, paddy straw and sorghum straw, respectively.     

Comparative ligninolytic and polysaccharolytic potentials of an alkaliphilic basidiomycete on native ligninocellulose

A comparison of the ligninolytic, cellulolytic and hemicellulolytic abilities of an alkaliphilic white-rot fungus. Coprinus fimetarius, on wheat straw under varying conditions of solid-substrate fermentation is presented. The extent of fractional degradation (percentage of the original dry weight of the fraction) of straw under an optimized set of cultural conditions (pH 9·0, moisture 65%, temperature 37°C, period 21 days) was in the following order: lignin (45%), cellulose (42%), hemicellulose (27%). Urea nitrogen favoured the degradation of lignin as well as cellulose and hemicellulose up to a certain level (1·5% sterile urea or 3% unsterile urea on a dry weight basis) beyond which the degradation of lignin was relatively more adversely affected than cellulose. The addition of phosphorus and sulphur was found essential for selective lignin removal. Increasing the C:N ratio by addition of free carbohydrates resulted in an overall decrease in the degradation wherein cellulose utilization was the most affected event. The pre-treatment (physical or chemical) of the substrate caused a general increase in biodegradation of lignin, cellulose and hemicellulose. The degrading activity of the fungus declined with the scaling-up of the fermentation particularly under non-sterile conditions.     

Optimization of cultivation and nutrition conditions and substrate pretreatment for solid-substrate fermentation of wheat straw byCoriolus versicolor

Bioconversion of wheat straw by solid-substrate fermentation (SSF) withCoriolus versicolor was optimized by varying its physiological parameters. Selective delignification (more lignin than holocellulose degradation) and increases in crude protein (CP) content andin vitro dry matter digestibility (IVDMD) were taken as the criteria to select optimum levels of these parameters. The fungus behaved optimally under the following set of cultural and nutritional conditions: pH 5.5, moisture level 55%, temperature 30 °C, duration of fermentation 21 d, form of inoculum—grain culture, turning frequency—once at mid-incubation, urea (nitrogen source) 1.5% (sterile) or 3.0% (nonsterile), single superphosphate (phosphorus+sulfur source) 1.0%, no addition of free polysaccharides (as whey or molasses). A maximum of 17.5% increase in IVDMD involving 4.3% degradation of lignin, was attained in the optimized SSF under laboratory conditions. The digestibility improvement could be further increased by using a substrate preteatment (physical/chemical/biological) in the following order of preference: NaOH treatment, urea or urine treatment, ensiling, steaming, grinding. For practical farm applications, urea treatment and ensiling appeared most feasible. The laboratory optimized process was also scaled up to 4 kg (sterile and unsterile) and 50 kg (unsterile) fermentations.     

Extraction of hemicellulose from ryegrass straw for the production of glucose isomerase and use of the resulting straw residue for animal feed

The hemicellulose fraction of ryegrass straw was extracted with NaOH and used for the production of glucose isomerase by Streptomyces flavogriseus. The level of hemicellulose extracted increased proportionately with increasing NaOH concentration up to about 4%, then the rate of increase slowed down. Hemicellulose extraction was facilitated by the combined application of heat and NaOH. Approximately 15% hemicellulose (12% as pentosan) could be obtained by treating straw with 4% NaOH for either 3 hr at 90°C or 24 hr at room temperature. The highest level (3.04 units/ml culture) of intracellular glucose isomerase was obtained when the organism was grown at 30°C for two days on 2% straw hemicellulose. The organism also produced a high yield of glucose isomerase on xylose or xylan. The NaOH-treated straw residue, after removal of hemicellulose, had approximately 75% higher digestibility and 20% higher feed efficiency for weanling meadow voles than untreated straw. Thus, the residue could be used as animal feed. A process for the production of glucose isomerase and animal feed from ryegrass straw was also proposed.     

Effect of chemical treatments on the degradability of cotton straw by rumen microorganisms and by fungal cellulase

Three different chemical treatments—sulfur dioxide, ozone, and sodium hydroxide—were applied on cotton straw, and the effect on cell-wall degradability was assessed by using rumen microorganism and Trichoderma reesei cellulase. Sulfur dioxide (applied at 70°C for 72 h) did not change the lignin content of cotton straw but reduced the concentration of hemicellulose by 48%. Ozone exerted a dual effect, both on lignin (a 40% reduction) and hemicellulose (a 54% decrease). The treatment with NaOH did not solublize cell-wall components. The in vitro organic matter digestibility with rumen fluid of cotton straw was increased significantly by ozone and SO₂ treatments, by 120% and 50%, respectively, but not by NaOH. T. reesei cellulase was applied on the chemically pretreated cotton straw at a low level (6 filter paper U/g straw, organic matter), and the release of reducing sugars was determined. The highest level of reducing sugars (30.6 g/100 g organic matter) was obtained with the O₃-cellulase combination, which solubilized 64% of the cellulose and 88% of the hemicellulose. the SO₂- and the NaOH-pretreated cotton straw were hydrolyzed by T. reesei cellulase to the same extent (21 g reducing sugars/100 g organic matter). The rumen fluid digestibility of the enzymatic ally hydrolyzed straw was not increased further over the effect already obtained with the chemical pretreatments. However, the fermentability of the combined treatments was increased markedly. In the O₃-cellulase-treated cotton straw, 83% of the rumen fluid digestible material consisted of highly fermentable components. Although ozone proved to be the most potent pretreatment for enzymic saccharification in this study, the absolute result was modest. The limited effect of the combined O₃-cellulase treatment was probably associated with the pretreatment limitations, but not with the enzyme level. Based on the differential response of the chemically treated cotton straw to attack by rumen microorganisms on the one hand, and by T. reesei cellulase on the other hand, a hypothesis has been suggested as to the location of lignin and hemicellulose in the cellwall unit of cotton straw.     

The effect of white-rot basidiomycetes on chemical composition andin Vitro digestibility of wheat straw

Five white-rot basidiomycetes were evaluated for their potential to improve ruminal degradation of wheat straw.Polyorus brumalis, Lyophyllum ulmarium III,Trametes gibbosa, Pleurotus ostreatus, and aPleurotus ostreatus mutant were incubated on wheat straw for 30 d at 28°C. Detergent fiber, crude protein andin vitro dry matter digestibility (IVDMD) were determined. The results showed increasing crude protein and ash contents in fungus-treated straw. IVDMD values were increased in straws treated withP. ostreatus, P. ostreatus mutant andT. gibbosa only. Relative to untreated wheat straw the detergent fiber content—neutral detergent fiber (NDF), and acid detergent fiber (ADF) was reduced in fungus-treated straw and out of three fractions—hemicellulose, cellulose and lignin, hemicellulose showed the largest proportionate loss whereas lignin the smallest one in all 5 samples of fungus treated straw.     

Effect of six species of white-rot basidiomycetes on the chemical composition and rumen degradability of wheat straw

This study was conducted to investigate changes in in vitro dry matter digestibility (IVDMD), volatile fatty acids (VFA) production and cell-wall constituent degradation in wheat straw treated with six white-rot fungi: Daedalea quercina, Hericium clathroides, Phelinus laevigatus, Inonotus andersonii, Inonotus obliquus, and Inonotus dryophilus. The incubation of wheat straw for 30 days at 28 C improved IVDMD from 41.4 (control) to 59.2% for D. quercina, 56.3% for H. clathroides, 50.2% for P. laevigatus, 51.4% for I. andersonii, 52% for I. obliquus, and 55.9% for I. dryophilus. In contrast, the growth of fungi was accompanied by the dry matter loss of wheat straw: 43% for D. quercina, 12% for H. clathroides, and 22-25% for the other fungi. It is evident that the increase in digestibility by D. quercina was not offset by a loss of dry matter. The total VFA production during the rumen fermentation of fungus-treated straw was slightly increased by H. clathroides and I. dryophilus only. Neutral detergent fiber (NDF) and acid detergent fiber (ADF) were reduced in fungus-treated straw. Out of the three fractions (hemicellulose, cellulose, and lignin), hemicellulose and lignin showed the largest proportionate loss after inoculation with the fungi D. quercina, H. clathroides, P. laevigatus, and I. obliquus. The other two fungi showed the largest proportionate loss in cellulose and hemicellulose contents. The results of this study suggest that the digestion enhancement of wheat straw colonized by white-rot fungi is regulated by complex factors including the degradation of structural carbohydrates and lignin.     

Differences between cattle and sheep in their digestion and relative intake of a mature tropical grass hay

The dry-matter digestibility (DMD) of a low quality tropical grass hay was much higher in cattle (49.6%) than in sheep (34.6%). This difference was not due to a difference in relative intake per kg liveweight (W^0.9) nor to a difference in the diet selected. However, neutral-detergent fibre (NDF) was digested better by cattle than by sheep. For each kg of dry matter consumed, cattle digested 415 g NDF and sheep 279 g NDF. This was because 60% more of the hemicellulose and 35% more of the cellulose were digested by cattle than by sheep.Differences between cattle and sheep in the concentrations of urea and sulphate in blood, and the relatively lower excretion of N, P and Ca by the cattle suggested that the rumen micro-organisms of the cattle were utilizing these nutrients better than those of the sheep. This could have increased microbial activity in the rumen and, hence, digestion of fibre.     

Alkali-explosion pretreatment of straw and bagasse for enzymic hydrolysis

Sugarcane bagasse and wheat straw were subjected to alkali treatment at 200 degrees C for 5 min and at 3.45 MPa gas pressure (steam and nitrogen), followed by an explosive discharge through a defibrating nozzle, in an attempt to improve the rate and extent of digestibility. The treatment resulted in the solubilization of 40-45% of the components and in the production of a pulp that gave saccharification yields of 80 and 65% in 8 h for bagasse and wheat straw, respectively. By comparison, alkali steaming at 200 degrees C (1.72 MPa) for 5 min gave saccharification yields of only 58 and 52% in 48 h. The increase in temperature from 140 to 200 degrees C resulted in a gradual increase in in vitro organic matter digestibility (IVOMD) for both the substrates. Also, the extent of alkalinity during pretreatment appears to effect the reactivity of the final product towards enzymes. Pretreatment times ranging from 5 to 60 caused a progressive decline in the IVOMD of bagasse and wheat straw by the alkali explosion method and this was accompanied by a progressive decrease in pH values after explosion. In the alkali-steaming method, pretreatment time had no apparent effect with either substrate. An analysis of the alkali-exploded products showed that substantial amounts of hemicellulose and a small proportion of the lignin were solubilized. The percentage crystallinity of the cellulose did not alter in either substrate but there was a substantial reduction in the degree of polymerization. The superiority of the alkali-explosion pretreatment is attributed to the efficacy of fiber separation and disintegration; this increases the surface area and reduces the degree of polymerization.     

White-rot fungal conversion of wheat straw to energy rich cattle feed

In order to improve the digestibility and nutrient availability in rumen, wheat straw was subjected to solid state fermentation (SSF) with white-rot fungi (i.e. Pleurotus ostreatus and Trametes versicolor) and the fermented biomass (called myco-straw) was evaluated for biochemical, enzymatic and nutritional parameters. The fungal treatment after 30 days led to significant decrease (P < 0.05) in cell wall constituents viz, acid detergent fiber (ADF), neutral detergent fiber (NDF), hemicellulose, lignin and cellulose to the extent of 35.00, 38.88, 45.00, 37.48 and 37.86%, respectively in P. ostreatus fermented straw, while 30.04, 33.85, 39.90, 31.29 and 34.00%, respectively in T. versicolor fermented straw. However, maximum efficiency of fermentation in terms of low carbohydrate consumption per unit of lignin degradation, favoring cattle feed production was observed for P. ostreatus on the 10th day (17.12%) as compared with T. versicolor on the 30th day (16.91%). The myco-straw was found to contain significantly high (P < 0.05) crude protein (CP; 4.77% T. versicolor, 5.08% P. ostreatus) as compared to control straw (3.37%). Metabolizable energy (ME, MJ/kg DM), percent organic matter digestibility (OMD) and short chain fatty acids (SCFAs; mmol) production also increased considerably from control straw (4.40, 29.91 and 0.292) to a maximum up to P. ostreatus fermented straw (4.92, 33.39 and 0.376 on 20th day) and T. versicolor fermented straw (4.66, 31.74 and 0.334 on 10th day), respectively. Moreover, the myco-straw had lower organic carbon and was rich in nitrogen with lower C/N ratio as compared to control wheat straw. Results suggest that the fungal fermentation of wheat straw effectively improved CP content, OM digestibility, SCFAs production, ME value and simultaneously lowered the C/N ratio, thus showing potential for bioconversion of lignin rich wheat straw into high energy cattle feed.     

Effect of hydrolysing and oxidizing agents on the composition and degradation of wheat straw monosaccharides

Summary Wheat straw (WS) was treated with 5% sodium hydroxide, ozone and 5% sulfur dioxide at 70°C for 72 h, and the effect of treatments on monosaccharide composition and in vitro degradability by rumen microorganisms was studied. The major sugars, glucose and xylose, comprising about 90% of the total monosaccharides in the untreated WS were mainly confined to the cell walls. SO₂ exerted the greatest solubilizing effect, followed by ozone and NaOH; the respective values for the solubilized cell wall polysaccharides were: 26, 12 and 4.4%. One third of the total phenolics was oxidized by ozone, whereas, SO₂ exerted mostly a solubilizing effect on this fraction, converting 75% of it into soluble phenolics. In the NaOH treated WS 41% of the total phenolics were soluble, as compared to 22% in the untreated. The in vitro digestibility of monosaccharides in the untreated WS were initially high: 50% and 58% for xylose and glucose, respectively and 63% to 80% for the minor sugars. The SO₂ treatment resulted in an overall increase in digestibility of monosaccharides with values lying in the range of 90%. Sodium hydroxide was more efficient than ozone in enhancing the degradability of xylan and total sugars. The digestibility of cell wall sugars was increased from 52.4% to 84.4%, 63.4% and 72.3% by SO₂, O₃ and NaOH treatments respectively. Based on the present findings, it appears that wheat straw cell wall components are more sensitive to hydrolytic than to oxidative processes aimed at increasing its degradability by rumen microorganisms. SO₂ exerted on WS a multi-effect which was particularly suitable for increasing the digestibility of monosaccharides.     

The feeding value of ammoniated flax straw,wheat straw and wheat chaff for beef cattle

Two experiments were conducted to assess the feeding value of ammoniated and untreated flax straw, wheat straw and wheat chaff in comparison to a mixed bromegrass/alfalfa hay. Anhydrous ammonia was applied to the crop residues at the rate of 35 kg t⁻¹ dry matter. In the first experiment, the effect of ammoniation on crude protein, acid detergent fibre (ADF), neutral detergent fibre (NDF) and acid detergent lignin (ADL), digestible organic matter in vitro and in vivo (DOM%), ADF and NDF digestibility of the crop residues was determined. In the second experiment, ammoniated flax straw, ammoniated wheat straw, ammoniated and untreated wheat chaff, each supplemented with barley, were compared to bromegrass/alfalfa hay as feed sources for wintering beef cows.Ammoniation increased the crude protein content of the crop residues ∼2-fold. Wheat straw DOM in vitro and in vivo was not increased by ammoniation. Ammoniation increased the DOM in vitro of wheat chaff from 36.3 to 46% and flax straw from 35.2 to 46.3%. The DOM in vivo increased from 53.3 to 63.4% (P < 0.05) for wheat chaff and from 33.9 to 58.4% (P < 0.05) for flax straw following ammoniation. Digestibility of ADF increased from 9.9 to 43.9% (P < 0.05) and of NDF from −0.6 to 37.9% (P < 0.05) in flax straw with ammoniation. Non-significant increases in ADF and NDF digestibility were observed for all other crop residues. Lignin content was not changed in the crop residues by ammoniation.In the winter feeding trial, young cows gained more weight than older cows (P < 0.05). Average daily gains of cows were greatest for hay followed by ammoniated flax straw, ammoniated chaff, untreated chaff and ammoniated wheat straw rations (P < 0.05). Increases in backfat in the younger cows was greatest with hay and ammoniated flax straw, followed by ammoniated chaff and ammoniated wheat straw (P < 0.05). Untreated chaff caused no increase in backfat thickness.Ammoniated flax straw (3.2 kg day⁻¹) given with barley (5.6 kg day⁻¹), is similar in feeding value to medium quality bromegrass/alfalfa hay. Furthermore, wheat chaff and ammoniated wheat chaff show good potential as alternatives to hay in winter feeding.     

The effect on digestibility of a new technique for alkali treatment of straw

The Biotechnical Institute in Kolding, Denmark, in collaboration with the National Institute of Animal Science, Copenhagen, has developed a new method for dry chemical treatment of straw with NaOH. Treatment with up to 7% NaOH (percent of straw dry matter) linearly increased enzyme digestibility and digestibility in vitro, and also rate of digestion. Lye treatment reduced cell wall constituents in straw (NDF). Digestibility in sheep was increased by increments of NaOH up to, but not exceeding, 4–5%. Although the process omits washing of excess base from the product, unreacted NaOH did not appear great enough to create concern.     

Rumen degradability and intestinal digestibility of brewers' grains as affected by origin and heat treatment and of barley rootlets

The rumen degradability and intestinal digestibility of dry matter (DM) and nitrogen (N) of three samples of brewers' grains (BG) and three of barley rootlets (BR) were determined. Rumen degradability was determined by the nylon bag technique in three rumen fistulated wethers. Intestinal digestibility was determined by the mobile nylon bag technique in two duodenal fistulated wethers. N content ranged from 41.2 to 46.4 g/kg DM for BG, and from 42.8 to 53.7 g/kg DM for BR. N effective degradability (NED), calculated for rumen outflow rates determined in each sheep, ranged from 57.2% to 70.9% for BG and from 79.0% to 84.0% for BR. N intestinal digestibility (NID) determined on 8 h-rumen incubated residues, ranged from 84.9% to 89.8% for BG and from 67.3% to 81.3% for BR. Lower rumen degradability was partially compensated by higher intestinal digestibility, resulting in a smaller variation in the estimated amount of digestible bypass N, which ranged from 24.7% to 36.7% for BG and from 10.8% to 17.1% for BR. One BG sample was selected to study the effects of heat treatment (HT) on its chemical composition, rumen degradability and intestinal digestibility. The BG sample was either freeze-dried (UBG) or dried at 50°C (50BG), 100°C (100BG), 135°C (135BG) and 175°C (175BG). Total N content was not affected by HT, but the acid–detergent insoluble N (expressed as percentage of total N content) increased from 13.7% to 54.1%. HT reduced the NED (from 76.5% to 25.6%) and, as a consequence, the supply of undegraded N to the duodenum was increased by 1.2, 1.8, 2.4 and 3.2 times for 50BG, 100BG, 135BG and 175BG, respectively. Drying at 50°C and 100°C had no adverse effects on the NID determined on 8 h-rumen incubation residues (mean value of 84.3%), but drying at 135 and 175°C decreased it to values of 80.1 and 51.6%, respectively. As a consequence, the estimated amount of digestible bypass N was increased by 1.2, 1.8, 2.3 and 1.9 times when drying at 50°C, 100°C, 135°C and 175°C, respectively.     

Studies on ammonia-treated straw. II. Fixation of ammonia in treated straw by spraying with acids

Ammonia-treated barley straw (NH₃ straw) was sprayed with either formic, acetic or phosphoric acid immediately after opening the stack in order to capture the excess ammonia. The amount of acid applied was estimated to neutralize 100% of the ammonia added to the straw (30 kg NH₃/t straw). After spraying with acid the straw was stored in plastic bags for about 8 weeks at room temperature (15–20° C). When bags of NH₃ straw treated with acids were opened, there was very little smell of ammonia whereas there was a very strong smell from the bag of NH₃ straw without acid added.The nitrogen content of the straw (g/100 g DM) was for untreated straw, 0.88, NH₃ straw without acid, 2.50, and NH₃ straw with added formic acid, 3.49, acetic acid, 3.81, and phosphoric acid, 2.27. The digestibility of organic matter determined in sheep was 47.3, 60.5, 59.0, 60.4 and 51.3 following the same order as above.It is concluded that spraying NH₃ straw with organic acids effectively reduces the loss of ammonia and increases the nitrogen content of the straw. Another advantage of this is that the air pollution with ammonia which may occur in the barn when the straw is not well aired is effectively prevented.Spraying with organic acids had no negative effect on the digestibility of the straw. The nitrogen supply and the digestibility of nitrogen in the animal seemed to be markedly improved.     

Condition stabilization for <Emphasis Type="Italic">Aspergillus niger</Emphasis> FCBP-198 and its hyperactive mutants to yield high titres of α-amylase

A number of substrates were tested for the cultivation of microorganisms to produce a host of enzymes. The effect of different substrates (wheat and rice straw, sugar cane waste, wood waste), incubation temperatures (20–40°C), initial pH levels (3.5–9.0), incubation periods (0–72 hours) and nitrogen sources (ammonium sulfate, urea, peptone, yeast extract, sodium nitrate) on growth and α-amylase activity was studied for the native and mutant strains. Maximum enzyme activity was observed at 1.5% wheat straw for Aspergillus niger FCBP-198 and An-Ch-4.7 and at 2% wheat straw for An-UV-5.6, with sodium nitrate as a principle nitrogen source. The optimum temperature for maximum enzyme activity was 30°C for the parental strain, while An-UV-5.6 and An-Ch-4.7 thrived well at 32.5°C. The best conditions of pH and incubation duration were 4.5 and 48 hours, respectively, for all the strains. Mass production under preoptimized growth conditions demonstrated the suitability of wheat straw for swift mycelial colonization and viability.     

Effect of ozonolysis pretreatment on enzymatic digestibility of wheat and rye straw

Wheat and rye straws were pretreated with ozone to increase the enzymatic hydrolysis extent of potentially fermentable sugars. Through a 2(5-1) factorial design, this work studies the influence of five operating parameters (moisture content, particle size, ozone concentration, type of biomass and air/ozone flow rate) on ozonization pretreatment of straw in a fixed bed reactor under room conditions. The acid insoluble lignin content of the biomass was reduced in all experiments involving hemicellulose degradation. Near negligible losses of cellulose were observed. Enzymatic hydrolysis yields of up to 88.6% and 57% were obtained compared to 29% and 16% in non-ozonated wheat and rye straw respectively. Moisture content and type of biomass showed the most significant effects on ozonolysis. Additionally, ozonolysis experiments in basic medium with sodium hydroxide evidenced a reduction in solubilization and/or degradation of lignin and reliable cellulose and hemicellulose degradation.     

Effect of storage and processing of barley on its utilization by pigs and rats

Grain of 16.7% moisture content was stored in exprimental silos by four methods. These were: (1) controlled environment (a sealed container); (2) addition of 1% acid mixture (60 acetic acid: 40 propionic acid); (3) addition of 3.2% sodium hydroxide in a 32% solution to give 21.8% moisture content; and (4) air-dried (82°C) to 13.3% moisture.After 9 months storage, apparent digestibility of dry matter, nitrogen and neutral detergent fibre was measured with pigs, while true protein digestiblity, biological value and net protein utilization were measured with rats.With pigs, there was no treatment effect on dry matter digestibility, but neutral detergent fibre digestibility was reduced in the dried barley. The apparent protein digestibility was markedly depressed to 44.5% for the alkali-treated grain compared with a mean of 65.1% for the other treatments (P < 0.001). In the rat trial, true digestibility of nitrogen and biological value were severely depressed (P < 0.001) by alkali treatment, but differences between the other treatments were relatively small.