Straw Particle Size Research Articles

Effects of physical form and wheat straw level in the diet on growth performance, nutrient digestibility, rumen papillae morphometry, and carcass characteristics in Lohi lambs

Context To achieve maximum growth and decrease fattening periods farmers tend to use a high concentrate diet in the total mixed ration (TMR). A larger particle size of straw may increase the concentrate level in the TMR and improve the performance without affecting the rumen health of lambs. Aims This study aimed to evaluate the effects of physical form (PF) and wheat straw levels (SL) in the diet on growth performance, rumen health, and carcass characteristics of lambs. Methods Thirty-two male Lohi lambs (31.5 ± 2.5 kg, age 6–7 months) were randomly assigned to four treatments in a 2 × 2 factorial arrangement with two physical forms [pelleted, conventional mashed] and two levels of straw (15% and 25%). The experiment lasted for 16 weeks including 2 weeks for dietary adaptation, 13 weeks for growth data collection, and 1 week for digestibility. Key results Lambs fed pelleted and 15% straw diets had greater dry matter intake than those offered mashed and 25% straw diets. Lambs fed 15% pelleted straw TMR displayed a greater final bodyweight, average daily gain, and feed efficiency than the other treatments. Dry matter and organic matter digestibility were higher in lambs fed on the pelleted and 15% straw diets compared to those fed on the mashed and the 25% straw diets. However, neutral detergent fibre digestibility was higher in the lambs fed 15% straw than those fed 25% straw diets. Lambs fed pelleted and 15% straw diets had longer papillae (P < 0.05), covering greater surface area than those fed on the mashed and 25% straw diets. Lambs fed on the pelleted and 15% straw diets had greater (P < 0.05) marbling score, rib eye area, empty live weight, hot carcass weight, and fat content than the lambs fed mashed and 25% straw diets. Conclusion Greater digestibility and feed intake of lambs fed a 15% pelleted straw TMR led to better growth performance, and improved carcass quality. Implications Feeding wheat straw-based pelleted TMR with 15% straw ground at 8 mm shows great potential to enhance the sustainable lamb production system in Pakistan.

Investigation of technology for composting mixed deer manure and straw.

Composting is an effective method for utilizing agricultural straw waste and livestock manure resources. Using deer manure and corn straw as raw materials, the changes in various indexes were studied during composting under different initial C/N ratios, initial moisture contents, and particle sizes of corn straw, and compost maturity was evaluated. Moisture content, total organic carbon content, and C/N ratio all declined during composting, while total nitrogen, total phosphorus, total potassium, pH, germination index, and electrical conductivity increased. The grey relational analysis method was used to evaluate maturity. The results showed that a mixture of stalk and deer manure with initial moisture content of 55%, initial C/N ratio of 30:1, and a straw particle size of 1.5-3.5 cm constituted the optimal experimental conditions. Taguchi analysis indicated that initial moisture content exerted the greatest influence on compost maturity, followed by initial C/N ratio and crushed straw particle size. This study provides an important reference for the utilization of compost derived from a mixture of livestock manure and straw.

Thermal conductivity of rice straw polypropylene particleboard

The availability of rice straw in Indonesia, including in some other Asian countries, is very abundant. However, it has not been used optimally. One possibility of using rice straw is for heat insulation in buildings. This study aims to analyze the thermal conductivity of rice straw polypropylene composite/particleboard. In this study, particulate composites from rice straw have been produced by using recycled plastic polypropylene (homopolymer) as adhesive. The particle size of rice straw used in this study was 20 mesh. The composition of rice straw and polypropylene were varied (the ratio of rice straw particle to polypropylene is 30/70 wt. %, 40/60 wt. %, 50/50 wt. %, and 60/40 wt. %). The composite samples were produced by using a hot press with 3 tons of load. The thermal conductivity of rice straw composite samples has been measured. We found that our composite thermal conductivity is 0.223 (±0.015) W/m °C for rice straw 30 wt.% and polypropylene 70 wt. %. For rice straw composition 60 wt. %, its thermal conductivity reduces to 0.191 (±0.002) W/m °C. The composite thickness swelling is found to be 0.76 (±0.26) % for rice straw 30 wt.% (after 24 hours immersing in water). The percentage of thickness swelling is 1.80 (±0.10) % for rice straw 60 wt. %. The results of our study revealed that the thermal conductivity of rice straw composite decreased as the thickness swelling increased. This behavior is related to the porosity of the composite.

Effects of wheat straw particle size as a free-choice provision on growth performance and feeding behaviors of dairy calves

In the dairy calf feeding, supplementation of forage to the starter feed is commonly practiced. However, data are insufficient about how changes in particle size (PS) of forage affect calf performance and behavior in a free-choice forage provision system. This study aimed to assess the effects of supplementing wheat straw varying in PS on performance, skeletal growth characteristics, ruminal pH, nutritional behaviors, and blood metabolites of dairy calves. Forty-eight Holstein calves (43.8 ± 3.2 kg of BW) from d 15 of age were randomly assigned to one of the four treatments (n = 12/treatment; six males and six females): (1) starter without wheat straw supplementation (CON), (2) CON supplemented with wheat straw chopped at 1 mm geometrical mean particle length (GMPL) (fine PS), (3) CON supplemented with wheat straw at 4 mm GMPL (medium PS), and (4) CON supplemented with wheat straw at 7 mm GMPL (long PS). The calves were given ad libitum access to feed and water throughout the study. All calves were weaned on d 56 of age and continued the experiment until d 90. The starter, wheat straw, and total solid feed intakes were not affected by GMPL of wheat straw; however, CON calves had a lower solid feed-, total DM- and NDF-intake than calves offered wheat straw. Further, ADG, weaning, and final BWs as well as feed efficiency were similar between treatments. No difference was observed in growth rate of hip height, hip width, body barrel, wither height, and heart girth among treatments, however, wheat straw supplemented calves tended to have greater body length at weaning. Blood concentration of serum β-hydroxy butyrate was greater in wheat straw supplemented calves compared with CON calves on d 56 and 90. Calves supplemented with wheat straw spent more time eating starter and forage, lying and ruminating and less time for standing and non-nutritional behaviors compared with the CON calves on d 49 and 63 of the study. Moreover, calves offered wheat straw had greater ruminal pH than CON calves at 4 and 8 h after offering starter feed on d 35. In conclusion, supplementing wheat straw as a free-choice increased solid feed intake, rumen pH, and calves' welfare, however, PS of wheat straw had no effect.

Mitigating bed agglomeration in a fluidized bed gasifier operating on rice straw

Fluidized bed gasifier is a promising technology with respect to converting biomass to useful energy. Bed agglomeration is an operational challenge that arises during fluidized bed gasification with rice straw as raw materials. Rice straw contains high amounts of potassium and other components that may lower the melting point of ash, causing bed agglomeration. Using alternative bed materials such as alumina, in the place of silica, can mitigate this problem. In Thailand, rice straw is an agricultural by-product of the rice milling processes, produced in large quantities every year. Usually, rice straw management comprises open field burning, which releases greenhouse gases, particulate matter, and other pollutants. In this paper, the behaviors of bed agglomeration and defluidization were investigated during the fluidized bed gasification of rice straw, using silica and alumina as bed materials. The effect of the percentage ratio of silica and alumina (0:100; 25:75; 50:50; 75:25; 100:0) was examined. The operating parameters were as follows: rice straw particle size of 425–850μm, reaction temperature of 700–900 °C, and equivalence ratios (ER) of 0.2 and 0.4. The results showed that the percentage ratio of silica and alumina, 0:100 at 700 °C, had extended the defluidization time of 60 min. The effect of equivalence ratio on bed agglomeration was found to be apparently heightened at a high temperature. The result of SEM/EDX analysis showed that the major elements at the linkage point of the agglomerated particle were Si, K, and Ca, with regard to any proportion of the alumina bed and temperature. In conclusion, low temperature agglomerate formation can be explained by a K2O-CaO-Si2O phase diagram. The results from this investigation can be applied to biomass-fluidized bed gasification, where bed agglomeration entails a plant shutdown and is expensive in terms of maintenance.

Particle Size Effect on Mechanical and Physical Properties of Rice Straw Epoxy Resin Particleboard

Rice straw is one of the agricultural residues that can be used to form a composite such as particleboard. In this study, the effect of rice straw particle size on the mechanical and physical properties of rice straw epoxy resin particleboard has been investigated. The rice straw particles sizes were varied for 40 mesh, 50 mesh, and 60 mesh. The ratio of rice straw to epoxy resin was also varied for 80 : 20 vol.%, 85 : 15 vol.%, 90 : 10 vol.%, and 95 : 5 vol.%. Our results revealed that the mechanical properties (modulus of elasticity, modulus of rupture, and tensile strength) of particleboard strongly depend on the rice straw particle size. This behavior is the same for the physical properties (density and water absorption) of particleboard. The highest flexural strength (modulus of rupture), elastic modulus, and tensile strength of rice straw epoxy resin particleboard are obtained at the 50 mesh of rice straw particle size with its value of 6.15 kgf/mm2, 3280 kgf/mm2, and 0.60 kgf/mm2, respectively. However, the highest density is obtained at the 60 mesh of rice straw particle size, which is 0.87 g/cm3. The lowest water absorption (23%) is also obtained at the 60 mesh of rice straw particle size. Our finding indicates that the particle size plays a vital role in the reinforcement of particleboard.

Biological Pretreatment by Solid-State Fermentation of Oat Straw to Enhance Physical Quality of Pellets

Pelleting can increase the efficiency of handling and transportation of biomass. Pretreatment obtains lignin fragments by disrupting the lignocellulosic structure of biomass and ensures the high-quality compressed pellets. In this study, solid-state fermentation (SSF) is used as a biological method to improve the quality of pellets of oat straw. SSF of oat straw using Trametes versicolor 52J (TV52J) and Phanerochaete chrysosporium (PC) was conducted. Response surface methodology (RSM) was employed by using a four-factor, three-level Box–Behnken design with fermentation time (days), moisture content (%), particle size (mm), and fermentation temperature (°C) as independent parameters. Pellet density, dimensional stability, and tensile strength were the response variables. The optimization options of fermentation time (33.96 and 35 days), moisture content (70%), particle size (150 and 50 mm), and fermentation temperature (22°C) of oat straw pretreated with these two fungal strains were obtained. The microscopic structural changes of oat straw caused by biological pretreatment were investigated by scanning electron microscopy (SEM). Observation results of SEM showed that the connection between single fibers became relatively loose, and this was beneficial to improve the physical quality of the pellets.

Thermogravimetric analysis and reaction kinetics of lignocellulosic biomass pyrolysis

The elucidation of the biomass pyrolysis characteristics will provide valuable guidance for the design of pyrolysis devices. The pyrolysis kinetics characteristics of lignocellulosic biomass were studied by thermogravimetric analysis, and the main influencing factors, including biomass particle size, heating rate, and metal ion, were investigated. With a decrease in the particle size of rice straw and pine sawdust, the initial and final pyrolysis temperatures and the temperature of the maximum weight loss ratio decreased. Opposite results were obtained for Phoenix tree leaves. Furthermore, the initial release temperature of volatile matter and the temperature corresponding to the peak of the derivative thermogravimetric curves increased with an increase in heating rate. Moreover, the pyrolysis activity of rice straw decreased significantly after deashing but increased with the addition of potassium. The pyrolysis kinetics parameters were calculated by the Coats–Redfern, Doyle, and the distributed activation energy model (DAEM) methods. The apparent activation energy of pyrolysis was the lowest, varying between 30 and 70 kJ/mol, according to the fitting results of the Coats–Redfern method. The apparent activation energies calculated by the DAEM and Doyle methods are similar, and are 67.6, 245.8, and 271.8 kJ/mol for rice straw, pine sawdust and Phoenix tree leaves, respectively.

Effects of replacing canola meal with camelina expeller on intake, total tract digestibility, and feeding behavior of beef heifers fed high-concentrate diets.

To assess the effect of inclusion of camelina expeller in beef cattle diets, 24 Simmental heifers were used. Two experiments were carried out. In the first, two free-choice tests, one without and another with molasses, were conducted to know the preference of animals for a total mixed ration (TMR) made with a 90 to 10 concentrate to barley straw ratio, where canola meal (CM) or camelina expeller (CE) was used in the concentrate as a protein source. Heifers were allotted in four pens with two independent feedbunks, one for each diet. In the second, a replicated 4 × 4 Latin square design was used to assess the effects of the replacement of CM with CE on intake, digestibility, and sorting and animal behavior. The experiment was performed in four 28-d periods during which groups of three animals were allotted in each pen of 12.5 m2. Diets were formulated with a 90 to 10 concentrate to barley straw ratio and fed as TMR, and they were designed to contain 1) CM as main protein source and 0% of CE (0CE), 2) 3% of CE replacing CM (3CE), 3) 6% of CE replacing CM (6CE), and 4) 9% of CE replacing CM (9CE). In the free-choice test without molasses, heifers showed a greater preference for CM than for CE (38.6 vs. 8.7 kg/d; P < 0.001). When molasses were added to the diet, the preference for CM was maintained (39.1 vs. 9.8 kg/d; P < 0.001). Dry matter (DM), organic matter (OM), crude protein (CP), and neutral detergent fiber (NDF) intake was unaffected by the level of replacement of CM by CE (P > 0.10), and there was no effect of this replacement on DM, OM, CP, and NDF apparent digestibility (P > 0.10). Intake of long particle size increased lineally as CE proportion increased (P = 0.015). In addition, extension of sorting behavior for long particle size tended to increase lineally (P = 0.07), and sorting against this particle size was detected in 0CE and 3CE, but not in 6CE and 9CE (P < 0.05). However, the results recorded for long particle size intake and for sorting behavior against these particles did not translate into more time spent ruminating in heifers fed diets with higher proportion of CE. In conclusion, when canola meal was replaced with camelina expeller at more than 14% of inclusion, heifers preferred the canola meal diet. However, replacing canola meal with camelina expeller up to 9% of inclusion in diets for beef cattle did not affect intake and digestibility but promoted a greater intake of long particle size of barley straw.

Physical and chemical properties of particleboard made of rice straw and plastic waste

Rice straw is agricultural waste which hasn’t been used optimally yet, especially in Indonesia. Meanwhile, rice straw contains cellulose that can be used form composite such particleboard. In this study, the physical and chemical properties of particleboard made of rice straw particle and polypropylene from plastic waste as adhesive were investigated. The rice straw and polypropylene compositions were varied: 30:70, 40:60, 50:50, and 60:40 wt.%. The rice straw particle sizes were varied for 40 mesh, 50 mesh, and 60 mesh for each composition. X-Ray Fluorescent has been used to measure the chemical composition of our particleboard. The density of particleboard is 0.59-0.77 g / cm3. Its thickness swelling is less than 2%. Both density and thickness swelling has met the requirement for Indonesian Standard of particleboard. Our results showed that the density of particleboard strongly depends on rice straw particle size. As the particle size decreases, the density increases. The particle size of rice straw affects the thickness swelling of particleboard. The thickness swelling decreases as the particle size decreases. The major constituents of our particleboard are the SiO2, CaO, K2O. Our finding showed that the particle size has an essential role in the physical properties of particleboard.

Integrated process for bioconversion of paddy straw, cheese whey and molasses into ethanol

The present study on co-fermentation of paddy straw and cheese whey was carried out to assess the efficacy of whey as nutritional supplement for bioethanol production. Also, co-fermentation of paddy straw and molasses was carried out for enhanced ethanol production to make downstream processing and purification process easier. For agro-residues like paddy straw, breaking of recalcitrant lignin sheath is the first and success determining step in bioethanol production. To achieve this efficiently, five factors optimized were temperature, pressure, pH, residence time and particle size of paddy straw. Paddy straw (particle size: 0.5 mm) immersed in 2% sodium hydroxide solution (pH 10.0) in 1:10 was subjected to delignification using steam collected under pressure (temperature 121°C; pressure 15 psi) for 1 h. This resulted in 83.3% lignin removal with 86.4% cellulose and 11.1% hemicellulose recovery. Polysaccharide rich substrate was saccharified using commercial enzyme loaded at 7.5 FPU g-1 substrate at 50°C for 2 h. Hydrolyzed substrate was fermented with yeast strain Candida utilis. The combined fermentation of paddy straw with cheese whey increased ethanol production from 29.0 mL L-1 to 31.0 mL L-1 without yeast nutrient supplementation and with molasses increased to 51.0 mL L-1 ethanol with yeast nutrient supplementation.

314 How physically effective fiber affects ruminal pH in beef cattle fed high-concentrate diets

Abstract To assess the effect of physically effective fiber (peNDF) on ruminal pH, 8 Simmental heifers with 258±5.7kg BW were randomly assigned to 1 of 4 treatments in a replicated 4x4 Latin square design. Diets were formulated with an 83 to 17 concentrate to straw ratio, and offered ad libitum as total mixed ration. Barley straw was chopped with a feeder wagon, and then processed either by: a) sifting with the 3-screen Penn State Particle Separator to obtain straw particle size greater than 4 mm, or b) grinding in a hammer mill through a 2-mm screen to obtain straw particle size lesser than 4 mm. Treatments after mixing the processed straws to obtain different peNDF proportions were: 5%, 7%, 9%, and 11%. Concentrate was ground through a 3-mm screen and manually mixed with the straw. The study was performed in 4 3-wk periods: 2-wk diet adaptation and 1-wk sampling. A ruminal bolus (smaXtec, Graz, Austria) was orally inserted in each heifer to measure ruminal pH every 10 min. Dry matter intake was individually measured. Data were analyzed using the mixed procedure of SAS. No significant effects were found in average and minimum pH (6.66 and 5.87 on average, respectively). Time under pH lesser than 5.8 was significantly longer (P &amp;lt; 0.01) in 5% (134 min/d) than 7%, 9% and 11% (63 min/d on average). Time under pH lesser than 5.6 tended to be longer (P = 0.074) in 5% (65 min/d), and shorter in 9% and 11% (25 min/d on average). Time under pH lesser than 5.5 was unaffected by treatment (23 min/d on average). Intake of DM was greater (P &amp;lt; 0.001) in 5% and 7% than 9% and 11%. These results suggest that the risk of subclinical acidosis decreases from 7 to 11% of peNDF, but DMI also decreases in 9% and 11%.

Effects of rice straw structure on chaetoglobosin A production by Chaetomium globosum CGMCC 6882

As the most abundant macromolecules in nature, lignocelluloses are served as a promising and renewable source for sustainable production of high value chemical compounds. In present work, extrusion pretreatment with 23% (w/w) distilled water, 2% (w/w) glycerol and 1 g/L NaHCO3 as moisture agent, not only reduced the particle size, crystallinity and component contents (cellulose, hemicelluloses and lignin) of rice straw, but also effectively enhanced chaetoglobosin A yield and degradation rate of rice straw by C. globosum CGMCC 6882. Meanwhile, mycelial biomass of C. globosum CGMCC 6882 increased from 2.9 g/L to 7.0 g/L, mycelia growth time reduced by 2 days and chaetoglobosin A titer increased from 108.4 mg/L to 270.2 mg/L, representing an increase of 149.3%. Furthermore, degradation rate of rice straw by C. globosum CGMCC 6882 increased from 28.93% to 65.38%. This work provides a good guidance for production of chaetoglobosin A from lignocelluloses.

A morpholinium ionic liquid for rice straw pretreatment to enhance ethanol production

Rice straw was successfully pretreated with a novel and inexpensive morpholinium ionic liquid, 1-H-3-methylmorpholinium chloride ([HMMorph][Cl]). The influence of water (30, 40, 50% w/w) and dimethyl sulfoxide (DMSO) (10, 30% w/w), as co-solvents, pretreatment time (2, 3, 5 h), temperature (90, 105, 120 °C), solid loading (5, 6.7, 10% w/w), and straw particle size (<0.177, 0.177–0.841 mm, and 0.841–2 mm) were investigated for maximum ethanol production. The best results were obtained in 50% water, at 120 °C and 5% (w/w) solid loading for 5 h from 0.177 – 0.841 mm straw particles. The hydrolysis yield was increased from 33.2% to 70.1%, while ethanol production yield was improved from 21.9% to 64% of the theoretical maximum. The performance of the IL was comparable to 1-ethyl-3-methylimidazolium acetate. Simple synthesis process and dilute solution required for the pretreatment with [HMMorph][Cl] offers cost reductions in the use of ILs in biofuel production.

Optimization of agricultural wastes liquefaction process and preparing bio-based polyurethane foams by the obtained polyols

Agriculture wastes, rice straw (RS), oilseed rape straw (OS), wheat straw (WS) and corn stover (CS) were liquefied in mixture solvents of polyethylene glycol 400 (PEG400) and ethylene glycol (EG) with sulphuric acid as catalyst. RS and OS liquefaction process were optimized by investigating influences of liquid and solid ratio, straw particle size, ratio between PEG and EG, catalyst dosage, reaction temperature and reaction time. Liquefactions of WS and CS were used to verify the optimal design. 79.0% of RS, 93.7% of OS, 88.3% of WS and 87.4% of CS were liquefied when these six parameters were 3:1, bigger than 40 mesh or 40–100 mesh, 7:1, 3%, 150 ºC and 40 min respectively. FT-IR and two-dimensional correlation spectroscopy (2D-COS) analysis showed that free OH and carboxyl associative OH groups in straw were more active than two associative OH groups during liquefaction. The obtained polyols are used to prepare bio-based polyurethane (PU) foam with better thermal stability, comparable mechanic properties successfully.

Manufacturing an Integrated Hammer Mill Unit for Grinding Rice Straw Intended for Multiple Applications

A rice straw milling unit manufactured in local workshop and the experimental evaluation was carried out in rice straw assembly station. The obtained result data indicated that the manufactured rice straw unit created solutions for all the problems faced the regular hammer mill machines in dealing with rice straw. The operation parameters under investigation and evaluation were air suction velocity of (1.97, 3.61, 5.37 and 6.91m/s), Number of hammers (54, 81 and 108 hammers) and Hammers thickness (2 and 5mm).The obtained results were for production the very low milled rice straw particle size applications such as MDF, papers making, silica jell and ethanol production must use air suction velocity of 5.37 m/s with number of hammers of 108 hammers with hammer thickness of 2mm. As this operation parameters obtained the following results 1.17 Mg/h main production rate in first cyclone, 43.95 kg/h, very fine product (straw dust) in second cyclone , 29.17 kW.h/Mg specific energy (SE), 153.63kg/m3 milled straw bulk density,0.43% losses in machine chamber, 1.93%losses with air blower output and particle size distribution percentage of 36.41% , 25.97% and 9.33% for particle size of ( 1.00mm), ( 0.60mm) and ( 2.80mm) and ( 2.00 mm) respectively.

Reduction of GHG emissions by utilizing biomass co-firing in a swirl-stabilized furnace

This study presents the numerical investigation of co-firing behaviour of pulverized straw particles with coal in air and O2/CO2 mixtures. Validation is conducted in a semi-technical once-through 30 kW swirl-stabilized furnace. Reference air-fuel (21% O2) and oxy-fuel (30% O2) cases were considered for four different coal/straw ratios (100% coal, 20% straw, 50% straw and 100% straw). AVL Fire is used as a CFD modelling tool. A comprehensive grid independency test was conducted considering three different grid sizes. Ignition performance, emission characteristics, heating profile, residence time were evaluated for different fuel ratios under air and oxy-fuel conditions. This work has shown that no significant changes occur to the fundamental combustion characteristics for straw compared to coal when burned in the O2/CO2 atmosphere to air firing case. It was found that with 20% straw sharing, sensible performances were observed similar to that of 100% coal combustion. Also a critical analytical analysis was conducted to investigate the heating performance for straw particle of different sizes (100 μm, 330 μm and 1000 μm). The heating profiles show significant differences between the three particle sizes assuming isothermal temperature gradient and heating by both radiation and convection. It is seen that the variation of the level of SO2 is not significant between air and oxy-firing cases. However, slightly less amount of SO2 is predicted in oxy-firing case. The reduction in NO is due to the effects of higher NO levels in the flue gas promoting gas-phase reduction, significantly higher levels of CO in the flame zone and the usage of a high-NOx burner in combination. The heating profiles for different size of straw particle suggest that there is a definite influence on the overall performance of the furnace. Larger particle do not ignite properly due to lower residence time leading to lower burnout. The possibility of burnout of the larger straw particle size is less due to less residence time in air-firing compared to oxy-firing case.

The impact of particle size of cellulosic residue and solid loadings on enzymatic hydrolysis with a mass balance

Rice straw has a great potential for ethanol production due to its richness in polysaccharides and abundant availability, however, for efficient utilization of these polysaccharides, size reduction is a prerequisite step. Therefore, biomass particle size plays a vital role for cellulosic ethanol commercialization. In this study, the effects of rice straw particle size on dilute acid pretreatment efficiency and enzymatic hydrolysis are investigated. Different sizes; 5, 10 and 20 mm were subjected to dilute acid pretreatment in a continuous pilot scale system with a horizontal screw feeder reactor followed by enzymatic hydrolysis at varying solids (10 and 15%) and enzyme dosages (5 and 10 FPU/g of pretreated residue). The glucan hydrolysis for 5, 10 and 20 mm are 65.6, 80.0 and 60.0% using 5 FPU and 79.5, 93.4 and 72.8% using 10 FPU/g pretreated residue respectively at 10% loading, whereas, at 15% it is significantly lower in respective experiment. Overall sugar recovery with 10 mm is 63.8 and 72.9% with 5 and 10 FPU respectively. RS with 10 mm biomass particle size at both solid loadings and enzyme dosages resulted in much higher enzymatic hydrolysis than others and in turn the overall sugar recovery and this was found to be due to the variation in the degradation products and pseudolignin contents in the pretreated biomass. The insight into the structural intricacies of biomass after pretreatment are studied using FT-IR and SEM revealing significant changes in biomass properties responsible for improved sugar recovery.

Factors affecting co-degradation of coal and straw to enhance biogenic coalbed methane

The formation of biogenic coalbed methane is stoichiometrically limited by relative deficiency of hydrogen in coal. As straw is rich in hydrogen and can be easily degraded by microorganisms, it is suggested that the co-degradation of coal and straw to produce biogenic methane can overcome these limitations. However, the factors affecting methane production in co-degradation of coal and straw were unclear. Here, the type and part of straw and the particle size of coal and straw were evaluated with respect to methane production from Qinshui Basin coal. The results showed that the biomethane yields in co-degradations of coal and different types of straw were all higher than that in degradation of only coal or only straw with the yield from rice and coal 25.36 times greater, the yield from sweet sorghum and coal 22.70 times greater, the yield from wheat and coal 19.90 times greater, and the yield from corn and coal 1.74 times greater. The co-degradation of coal and stems also showed a better enhancing effect than that of coal and roots and coal and leaves based on biogenic methane production. With respect to particle size, the coal had a greater influence on biomethane production than the straw. The highest methane production was obtained in the co-degradation with 0.125–0.150 mm of coal and 5 mm of rice straw. The affects were also shown to not correlate well with the additional of hydrogen. Therefore, it is more likely that the enhanced methane production is a result of stimulating the microbial biodegradation of coal. Further efforts would be made to find the specific compounds in straw which interact with coal directly, in order to better understand the mechanism of co-degradation between coal and straw, and make it simpler to improve biomethane production.

Short communication: Risk of subacute ruminal acidosis affects the feed sorting behavior and milk production of early lactation cows

The objective of this study was to determine if the risk of developing subacute ruminal acidosis, as potentially affected by dietary straw particle size, influenced the feed sorting, rumination behavior, and milk production of early lactation dairy cows. Upon calving, 41 multiparous Holstein cows were fed a total mixed ration with 9% wheat straw (dry matter basis) chopped (1) using a 2.54-cm screen (short; n = 21) or (2) using a 5.08-cm screen (long; n = 20). For the first 4 wk following calving, rumination behavior (recorded using data loggers attached to neck collars) and reticulorumen pH (recorded using wireless telemetry boluses) were monitored 24 h/d. Due to technical failures, analyses were conducted on 38 cows (n = 19 per treatment). Total mixed ration and orts samples were collected every 3 d to determine feed sorting. Based on an acidosis index, created using area under the curve data (reticulorumen pH < 5.8) normalized for dry matter intake, cows were categorized as either low (LR) or high (HR) risk for developing subacute ruminal acidosis (SARA). Low risk cows had higher mean (6.3 vs. 6.1), minimum (6.0 vs. 5.7), and maximum (6.7 vs. 6.5) reticulorumen pH than HR cows. Low risk cows also had less severe area under the curve values (1.5 vs. 49.4 pH × min/d) and spent less time below a reticulorumen pH threshold of 5.8 (21.9 vs. 309.2 min/d). Although total milk yield was unaffected by SARA risk, LR cows produced more 4% fat-corrected milk (47.2 vs. 41.9 kg/d) and milk fat (2.1 vs. 1.8 kg/d) than HR cows. A SARA risk category × treatment interaction was detected for sorting all fractions of the diet; HR cows on the long treatment sorted against the longest particles in the diet, whereas LR cows on the same treatment did not sort this fraction, suggesting that SARA risk may be mitigated by a more balanced intake of physically effective fiber. High risk cows on the short treatment consumed the longest dietary particles as predicted, and sorted in favor of the physically effective medium and short particles. A SARA risk category × treatment interaction was detected for rumination behavior; within the long treatment, HR cows tended to ruminate less than LR cows (432.3 vs. 493.2 min/d). Overall, these results suggest that LR cows consumed a more balanced diet, whereas HR cows sorted their feed more, particularly when fed the diet containing long straw particles, which may have led to reduced rumination activity and yield of milk fat and fat-corrected milk.