Digestibility Of Corn Stover Research Articles

Flow-through pretreatment with strongly acidic electrolyzed water for hemicellulose removal and enzymatic hydrolysis of corn stover

The application of strongly acidic electrolyzed water (SAEW) in a flow-through system for the treatment of recalcitrant corn stover resulted in enhanced hemicellulose degradation at 160°C and 180°C compared to hydrochloric acid treatment under the same pH. Pretreatment conditions were optimized by varying the four main factors: pH, flow rate, temperature, and reaction time. About 96% of the hemicellulose was removed when corn stover was treated at 180°C for 20min, with SAEW at pH 2.0 and a flow rate of 10mL/min. The recovery of total monomeric and oligomeric xylose in the liquid fraction reached 93%. Using 30 filter paper units of cellulase per gram of cellulose, a digestibility of 100% was achieved under these conditions. Therefore, flow-through SAEW pretreatment is an efficient way to remove hemicellulose and improve enzymatic digestibility of corn stover.

Enhanced solid-state anaerobic digestion of corn stover by alkaline pretreatment

Alkaline pretreatment was applied to enhance biogas production from corn stover through solid-state anaerobic digestion. Different NaOH loadings (1%, 2.5%, 5.0% and 7.5% (w/w)) were tested for solid-state pretreatment of corn stover. Lignin degradation during pretreatment increased from 9.1% to 46.2% when NaOH concentration increased from 1.0% to 7.5%. The NaOH-pretreated corn stover was digested using effluent of liquid anaerobic digestion as inoculum and nitrogen source. NaOH loading of 1% did not cause significant improvement on biogas yield. The highest biogas yield of 372.4 L/kg VS was obtained with 5% NaOH-pretreated corn stover, which was 37.0% higher than that of the untreated corn stover. However, a higher NaOH loading of 7.5% caused faster production of volatile fatty acids during the hydrolysis and acidogenesis stages, which inhibited the methanogenesis. Simultaneous NaOH treatment and anaerobic digestion did not significantly improve the biogas production ( P > 0.05).

Protoplast Fusion between Geotrichum candidium and Phanerochaete chrysosporium to Produce Fusants for Corn Stover Fermentation

Lignin impedes the digestion of corn stover when used as an animal feed. Phanerochaete chrysosporium is an efficient lignindegrader. Geotrichum candidum can be used to produce single-cell protein. In this study, protoplasts of the two fungi were prepared and fused. After screening, one of the fusants, Fusant R1, was selected for corn stover fermentation. It decreased lignin from 109 to 54 g/kg and increased protein from 48 to 67 g/kg in corn stover. Comparison with their parental strains indicated that the fusant obtained the lignin-degrading ability from P. chrysosporium and the protein-accumulating ability from G. candidium.

Análisis químico y digestibilidad “in vitro” de rastrojo de maíz (Zea mays L.).

This experiment was conducted to evaluate the effects of chemical and physical treatments on the chemical composition and in vitro dry matter (IVDMD) and organic matter (IVOMD) digestibility of corn stover. Seventy five bales of corn stover (25 ground, 25 chopped, and 25 whole) were treated with 4% ammonia (NH3) of the dry matter weight. A completely randomized design with factorial array 2x3 (0.0 and 4.0% NH3 and three particle sizes). Results indicated that dry matter content decreased as particle size increased. Protein content increased by 110, 116 and 91 units for the ground, chopped and whole corn stover treated with NH3 with respect to the control. Ether extract increased by 7.3% for corn stover treated with NH3. Similar trend was followed by the ash content which increased by 6.0% for corn stover treated with NH3. Ammonia treatment affected negatively the neutral detergent fiber values by 20.0, 7.0 and 7.7% for ground, chopped and whole corn stover, respectively. Similar results were found for acid detergent fiber with values of 7.17, 12.53 and 11.42% lower for ground, chopped and whole corn stover, respectively; than those found for the untreated material. IVDMD and IVOMD were increased with NH3 treatment.

Effect of structural features on enzyme digestibility of corn stover

Corn stover was pretreated with excess calcium hydroxide (0.5 g Ca(OH) 2/g raw biomass) in non-oxidative and oxidative conditions at 25, 35, 45, and 55 °C. The enzymatic digestibility of lime-treated corn stover was affected by the change of structural features (acetylation, lignification, and crystallization) resulting from the treatment. Extensive delignification required oxidative treatment and additional consumption of lime (up to 0.17 g Ca(OH) 2/g biomass). Deacetylation reached a plateau within 1 week and there were no significant differences between non-oxidative and oxidative conditions at 55 °C; both conditions removed approximately 90% of the acetyl groups in 1 week at all temperatures studied. Delignification highly depended on temperature and the presence of oxygen. Lignin and hemicellulose were selectively removed (or solubilized), but cellulose was not affected by lime pretreatment in mild temperatures (25–55 °C), even though corn stover was contacted with alkali for a long time, 16 weeks. The degree of crystallinity slightly increased from 43% to 60% with delignification because amorphous components (lignin, hemicellulose) were removed. However, the increased crystallinity did not negatively affect the 3-d sugar yield of enzymatic hydrolysis. Oxidative lime pretreatment lowered the acetyl and lignin contents to obtain high digestibility, regardless of crystallinity. The non-linear models for 3-d hydrolysis yields of glucan ( Y g), xylan ( Y x), and holocellulose ( Y gx) were empirically established as a function of the residual lignin ( L) for the corn stover pretreated with lime and air.

Evaluation of producing fuel and chemicals from corn stover pre-treated with flue gas

Production of fuels and chemicals from corn stover is currently at the economic crossroads. Two problems, low yield and high cost, need to be resolved. One of the solutions to these problems is to improve digestibility of corn stover by using cheap chemicals. This paper explores the possibility of developing a low-cost corn fibre pre-treatment method with SO2 and fly ash in flue gas. An economic analysis of producing hydrogen and acetic acid from corn stover pre-treated with SO2 was conducted.

Microbial Pretreatment of Biomass: Potential for Reducing Severity of Thermochemical Biomass Pretreatment

Typical pretreatment requires high-energy (steam and electricity) and corrosion-resistant, high-pressure reactors. A review of the literature suggests that fungal pretreatment could potentially lower the severity requirements of acid, temperature and time. These reductions in severity are also expected to result in less biomass degradation and consequently lower inhibitor concentrations compared to conventional thermochemical pretreatment. Furthermore, potential advantages of fungal pretreatment of agricultural residues, such as corn stover, are suggested by its effectiveness in improving the cellulose digestibility of many types of forage fiber and agricultural wastes. Our preliminary tests show a three- to five-fold improvement in enzymatic cellulose digestibility of corn stover after pretreatment with Cyathus stercoreus; and a ten- to 100-fold reduction in shear force needed to obtain the same shear rate of 3.2 to 7 rev/s, respectively, after pretreatment with Phanerochaete chrysosporium.

Effects of Phenolic Compounds in Cell Walls of Orange and Artichoke By-Product Silages on In vitro Digestibility

Megías, M.D., Cherney, J.H. and Cherney, D.J.R. 1997. Effects of phenolic compounds in cell walls of orange and artichoke by-product silages on in vitro digestibility. J. Appl. Anim. Res., 12: 127–136. By-products of the canning industry are extensively used as ruminant fodder in some areas of the world Characterization of the phenolic content of these feeds and their influence on digestibility is lacking. Phenolic carbohydrate complexes were isolated from cellulose extracts of neutral detergent fiber from orange pulp (Citrus aurantium L.) and artichoke (Cynara scolymus L.) pulp after 100 days ensiling. The effect of the byproduct phenolic compounds on fiber digestion of corn stover (0.25 g) was determined by the addition of extracts at levels equivalent to 0.5, 1.0 and 2.0 g of neutral detergent fiber. Fiber digestion was inhibited (P>0.05), but only at the 2.0 g rate. Fiber digestion at this rate was more inhibited by orange pulp (79.3±1.44%) than artichoke extracts (23.12±1.5%). Ferulic acid was the predominant phenolic acid present in orange pulp, while vanillic acid was the primary phenolic acid in artichoke pulp. Difference in inhibition of fiber digestion may have been due to differences in phenolic acids and/or to the larger peak eluted with the orange pulp, indicative of larger quantities of the phenolic-carbohydrate complex in artichoke. Because large quantities of the extracts were required to elicit an effect, it appears unlikely that the phenolic-carbohydrate complexes in these by-products would pose a problem in most ruminant feeding situations.

Fiber Composition and in Vitro Digestibility of Corn Stover Fractions in Response to Ammonia Treatment

The composition and digestibility of corn stover leaves and stems after prolonged NH3 treatment was compared with that after isonitrogenous NH3 addition (NH3 control), represented by samples immediately frozen after initial NH3 application. Ammonia treatment decreased concentration of hemicellulose in leaves, particularly arabinose residues. Concentration of saponifiable hydroxycinnamic acids was reduced by NH3 treatment in upper stems only. Ammonia addition, compared to a H2O control, increased the extent of in vitro fiber degradation of all plant fractions but the rate of fiber degradation for leaves only. Ammonia treatment increased the extent of fiber degradation over NH3 addition in leaves but not in stems. The variable response to NH3 treatment among stover fractions of drought-stressed corn may be related to the high concentration of water-soluble carbohydrates in the stalks and immobilization of NH3-N with lignin. Keywords: Ammoniation; Zea mays; lignin; hemicellulose; hydroxycinnamic acids; NPN immobilization; digestibility

Effect of Cyclic Selection for High and Low Crushing Strength on Rind, Pith, and Whole Stalk Composition in Corn1

Two synthetic corn (Zea mays L.) populations were selected for high and low crushing strength through five cycles of recurrent selection. Stalk sections from the second internode above the ground were collected from the fifth cycle plants. The stalk sections were separated into pith and rind components and analyzed for lignin and cellulose. In one synthetic (MoSQA) the lignin percentages in the stalk sections were 16.6 and 19.2 for low and high crushing strength selections, respectively. Lignin percentages were 15.9 and 17.6, respectively, for the low and high crushing strength selections in the second synthetic (MoSQB). However, stalk lignin percentages for the high and low selections in each population were not significantly different from stalk lignin percentages in the original unselected populations. Lignin percentage of the pith was not affected by selection for crushing strength. In MoSQA the lignin percentage of the rind increased with increased crushing strength. Lignin percentage of the rind in MoSQB did not change. However, the proportion of rind in the stalk changed from 75.8 to 82.1% due to selection for low and high crushing strength.The changes in stalk composition were small relative to the large differences in crushing strength and lodging percentage between the high and low selections. This suggests that crushing strength and lodging resistance can be increased considerably without greatly affecting the composition, and presumably, the digestibility of corn stover.

Structural Composition and in vitro Dry Matter Disappearance of Brown Midrib Corn Residue1

The purpose of this research was to determine the effect of the brown midrib‐3 (bm3) gone on lignin percentage and in vitro dry matter disappearance of corn (Zea mays L.) stems and leaves sampled after grain harvest. Brown midrib‐3 and nearly isogenic normal corn hybrids were grown under field conditions at two locations and sampled at approximately 3, 6, and 9 weeks after grain harvest. An additional normal source represented by a commercial hybrid was also grown at one location. The stover portion of the plants was separated into leaves and stems. Samples were analyzed for structural composition and in vitro dry matter disappearance (IVDMD) using detergent solution and rumen fermentation techniques.The lignin percentage in leaves averaged 5.8 and 7.1% for bm3 and normal plants at the first location. IVDMD of the leaves at this location averaged 57.1 and 49.8%. Lignin percentage in stems averaged 5.4 and 11.6% for bm3 and normal plants. IVDMD of stems averaged 59.2 and 43.0%. The composition of commercial hybrid plants was similar to that of normal plants. At the second location, leaf lignin averaged 6.6 and 8.1% and IVDMD was 56.0 and 50.2% for bm3 and normal genotypes. Lignin averaged 7.0 and 12.4% and IVDMD averaged 50.1 and 39.0% for bm3 and normal stems.Lignin percentage increased and IVDMD decreased after grain harvest. However, differences between bm3 and normal genotypes were nearly as great at the last sampling as at the first, indicating that the differences in composition and digestibility of corn stover caused by the bm3 gene persist in the plant residue long after the grain has been harvested.