Particle size distribution of distillers dried grains with solubles (DDGS) and relationships to compositional and color properties

Eleven distillers dried grains with solubles (DDGS), processed from yellow corn, were collected from different ethanol processing plants in the US Midwest area. Particle size distribution (PSD) by mass of each sample was determined using a series of six selected US standard sieves: Nos. 8, 12, 18, 35, 60, and 100, and a pan. The original sample and sieve sized fractions were measured for surface color and contents of moisture, protein, oil, ash, and starch. Total carbohydrate (CHO) and total non-starch CHO were also calculated. Results show that there was a great variation in composition and color among DDGS from different plants. Surprisingly, a few DDGS samples contained unusually high amounts of residual starch (11.1-17.6%, dry matter basis, vs. about 5% of the rest), presumably resulting from modified processing methods. Particle size of DDGS varied greatly within a sample and PSD varied greatly among samples. The 11 samples had a mean value of 0.660mm for the geometric mean diameter (d(gw)) of particles and a mean value of 0.440mm for the geometric standard deviation (S(gw)) of particle diameters by mass. The majority had a unimodal PSD, with a mode in the size class between 0.5 and 1.0mm. Although PSD and color parameters had little correlation with composition of whole DDGS samples, distribution of nutrients as well as color attributes correlated well with PSD. In sieved fractions, protein content, L and a color values negatively while contents of oil and total CHO positively correlated with particle size. It is highly feasible to fractionate DDGS for compositional enrichment based on particle size, while the extent of PSD can serve as an index for potential of DDGS fractionation. The above information should be a vital addition to quality and baseline data of DDGS.     

Pilot scale fiber separation from distillers dried grains with solubles (DDGS) using sieving and air classification

Distillers dried grains with solubles (DDGS), the coproduct of fuel ethanol production from cereal grains like corn, is mainly used as cattle feed and is used at low inclusion levels in poultry and swine diets because of high fiber content. Elusieve process, the combination of sieving and air classification (elutriation), was developed in laboratory scale to separate fiber from DDGS to result in a low fiber product which would be more suitable for poultry and swine. In this pilot scale study, DDGS was sieved at a rate of 0.25 kg/s (1 ton/h) into four sieve fractions using a sifter and the three largest sieve fractions were air classified using aspirators to separate fiber on a continuous basis. Results were similar to laboratory scale. Nearly 12.4% by weight of DDGS was separated as Fiber product and resulted in two high protein products that had low fiber contents. Payback period for the Elusieve process in an existing dry grind plant processing corn at the rate of 2030 metric tonnes/day (80,000 bushels/day) would be 1.1 yr.     

Fermentation of Barley by Using Saccharomyces cerevisiae: Examination of Barley as a Feedstock for Bioethanol Production and Value-Added Products

The objective of this study was to examine the ethanol yield potential of three barley varieties (Xena, Bold, and Fibar) in comparison to two benchmarks, corn and wheat. Very high gravity (VHG; 30% solids) fermentations using both conventional and Stargen 001 enzymes for starch hydrolysis were carried out as simultaneous saccharification and fermentation. The grains and their corresponding dried distiller''s grain with solubles (DDGS) were also analyzed for nutritional and value-added characteristics. A VHG traditional fermentation approach utilizing jet-cooking fermentation revealed that both dehulled Bold and Xena barley produced ethanol concentrations higher than that produced by wheat (12.3, 12.2, and 11.9%, respectively) but lower than that produced by corn (13.8%). VHG-modified Stargen-based fermentation of dehulled Bold barley demonstrated comparable performance (14.3% ethanol) relative to that of corn (14.5%) and wheat (13.3%). Several important components were found to survive fermentation and were concentrated in DDGS. The highest yield of phenolics was detected in the DDGS (modified Stargen 001, 20% solids) of Xena (14.6 mg of gallic acid/g) and Bold (15.0 mg of gallic acid/g) when the hull was not removed before fermentation. The highest concentration of sterols in DDGS from barley was found in Xena (3.9 mg/g) when the hull was included. The DDGS recovered from corn had the highest concentration of fatty acids (72.6 and 77.5 mg/g). The DDGS recovered from VHG jet-cooking fermentations of Fibar, dehulled Bold, and corn demonstrated similar levels of tocopherols and tocotrienols. Corn DDGS was highest in crude fat but was lowest in crude protein and in vitro energy digestibility. Wheat DDGS was highest in crude protein content, similar to previous studies. The barley DDGS was the highest in in vitro energy digestibility.The growing need for energy independence and proposed renewable fuels has led recently to a major expansion of fuel ethanol production. In North America, this activity primarily uses corn as a feedstock. The need to find other cost-effective and efficient grains for ethanol production has increased in significance. Cereal grains are high in starch and are currently being utilized for ethanol production (26, 41). To ensure long-term viability of the industry, fermentation strategies that focus on holistic utilization of the feedstock that maximize value addition will increase in importance. The focus of industry is slowly moving from biorefineries that anticipate subsidy and government policy to integrated biorefineries that produce multiple products. Multiple product streams and integrated by-product management are thought to ensure better financial stability and opportunities for diversified income streams.Barley is a potential candidate for industrial ethanol production (10) since its ethanol yield is comparable to that of wheat but below that of American corn, which is currently the preferred industrial feedstock. Barley contains on average 63 to 65% starch, 8 to 13% protein, 2 to 3% fat, 1 to 1.5% soluble gums, 8 to 10% hemicellulose, ca. 2.9% lignin, and 2 to 2.5% ash (15, 27). Barley also contains a hull that could be fermented using cellulolytic enzymes, providing opportunities for integrated biorefineries that utilize more feedstocks than corn. Potential coproducts of ethanol production from barley include protein, fiber, fatty acids, tocopherols, and tocotrienols (40). The nutritional value of barley, based on amino acid content, is greater than that for corn and is not significantly affected by the fermentation process (40). A range of nutraceutical and functional food products, as well as amylase, amylase inhibitors, β-amylase, and oxalate oxidase, are found in barley grains and may have potential for extraction and commercial applications (6, 22, 33). Hull-less barley lines, high in both protein (particularly lysine) and starch, and low in fiber, have recently been developed (11, 14, 32). Since starch recovery and thus ethanol yields are lower for barley than corn, coproduct recovery becomes even more essential for profitability (43).Enzymes used for the pretreatment of grains prior to fermentation have traditionally been α-amylases and glucoamylases. The α-amylase decreases the viscosity of the mash (25) and performs the liquefaction of the pretreatment process. The liquefaction step is typically done at high temperatures of 100 to 120°C (38) with direct steam injection (jet-cooking). The α-amylase action serves to break starch at α-(1,4)-glucosidic bonds, producing smaller dextrin chains. During the saccharification step of the pretreatment, the dextrins produced by α-amylase are then acted on by glucoamylase. This conventional method has a considerable economic drawback, because the mash must undergo a cooking step prior to fermentation. Many industrial ethanol producers use jet-cooking to raise the mash temperature to 100 to 120°C. Because of this temperature requirement, the conventional process uses a large amount of energy to produce ethanol.Recently, a new line of cold starch hydrolyzing enzymes was developed. An example of these enzymes is Stargen 001, which is referred to as a raw starch hydrolyzing enzyme because starch is hydrolyzed to fermentable sugars while the temperature remains at or below a temperature of 48°C (38). Stargen 001 replaces the liquefaction and saccharification steps performed by conventional digestion enzymes (i.e., α-amylase and glucoamylase) and releases free glucose and other fermentable sugars for use by yeast cells. Stargen 001 is a cocktail of modified α-amylase and glucoamylase enzymes that work together to convert starch into dextrins, followed by the hydrolysis of dextrins to fermentable sugars (37, 38). With the absence of a cooking stage in the cold hydrolysis method, the potential exists that the dried distiller''s grain plus solubles (DDGS) produced by fermentation would have less damage so that the proteins contained in the DDGS could be of more value (18).The objectives of the present study were to examine the ethanol yield potentials of three barley varieties (Xena, Bold, and Fibar) and two benchmark grains (Pioneer Hi-Bred corn and CPS wheat) using conventional (jet-cooking) and cold starch hydrolysis with Stargen 001. In addition, dehulling was tested for the potential to increase ethanol yields, because hull does not contain fermentable starch; both hulled and dehulled mashes were studied where possible. The grains and their corresponding DDGS were analyzed for nutritional value and the presence of potential value-added products such as fatty acids, tocopherols, tocotrienols, sterols, and polyphenols.     

Effects of particle size distribution,compositional and color properties of ground corn on quality of distillers dried grains with solubles (DDGS)

Oftentimes, corn processors believe that ground corn (raw material) and distillers dried grains with solubles (DDGS) are interrelated in certain quality parameters. Yet, previous studies, although rather limited, have not established this relationship. In this study, six ground corn samples and their resulting DDGS were analyzed for particle size distribution (PSD), using a series of six selected US standard sieves: Nos. 8, 12, 18, 35, 60, and 100, and a pan. The original sample and sieve sized fractions were measured for contents of moisture, protein, oil, ash and starch, and surface color. Total carbohydrate (CHO) and total non-starch CHO were also calculated. Results show that the geometric mean diameter (d_gw) of particles varied with individual corn and DDGS samples, and that d_gw of DDGS was larger than that of corn (0.696 vs. 0.479 mm, average values), indicating that during conversion of corn to DDGS, certain particles became enlarged. For d_gw and mass frequency of individual particle size classes, the relationship between ground corn and DDGS varied, but PSD of the whole sample was well correlated between them (r = 0.807). Upon conversion from corn to DDGS, on an average, protein was concentrated 3.59 times; oil, 3.40 times; ash, 3.32 times; and total non-starch CHO, 2.89 times. There were some positive correlations in contents of protein and non-starch CHO and in L value between corn and DDGS. Yet, variations in nutrients and color attributes were larger in DDGS than in corn. For either corn or DDGS, these variations were larger in sieved fractions than in the whole fraction. Raw material, processing method and addition of yeasts are among major factors considered for causing larger variations in these attributes among DDGS. The study partially supports the common belief by processors that quality attributes of corn affect those of DDGS.     

Changes in mineral concentrations and phosphorus profile during dry-grind processing of corn into ethanol

For determining variation in mineral composition and phosphorus (P) profile among streams of dry-grind ethanol production, samples of ground corn, intermediate streams, and distillers dried grains with solubles (DDGS) were obtained from three commercial plants. Most attributes (dry matter concentrations) increased significantly from corn to cooked slurry but fermentation caused most significant increase in all attributes. During centrifugation, more minerals went into thin stillage than wet grains, making minerals most concentrated in the former. Mineral increase in DDGS over corn was about 3 fold, except for Na, S, Ca, and Fe. The first three had much higher fold of increase, presumably due to exogenous addition. During fermentation, phytate P and inorganic P had 2.54 and 10.37 fold of increase over corn, respectively, while relative to total P, % phytate P decreased and % inorganic P increased significantly. These observations suggest that phytate underwent some degradation, presumably due to activity of yeast phytase.     

Improvement in fermentation characteristics of degermed ground corn by lipid supplementation

With rapid growth of fuel ethanol industry, and concomitant increase in distillers dried grains with solubles (DDGS), new corn fractionation technologies that reduce DDGS volume and produce higher value coproducts in dry grind ethanol process have been developed. One of the technologies, a dry degerm, defiber (3D) process (similar to conventional corn dry milling) was used to separate germ and pericarp fiber prior to the endosperm fraction fermentation. Recovery of germ and pericarp fiber in the 3D process results in removal of lipids from the fermentation medium. Biosynthesis of lipids, which is important for cell growth and viability, cannot proceed in strictly anaerobic fermentations. The effects of ten different lipid supplements on improving fermentation rates and ethanol yields were studied and compared to the conventional dry grind process. Endosperm fraction (from the 3D process) was mixed with water and liquefied by enzymatic hydrolysis and was fermented using simultaneous saccharification and fermentation. The highest ethanol concentration (13.7% v/v) was achieved with conventional dry grind process. Control treatment (endosperm fraction from 3D process without lipid supplementation) produced the lowest ethanol concentration (11.2% v/v). Three lipid treatments (fatty acid ester, alkylphenol, and ethoxylated sorbitan ester 1836) were most effective in improving final ethanol concentrations. Fatty acid ester treatment produced the highest final ethanol concentration (12.3% v/v) among all lipid supplementation treatments. Mean final ethanol concentrations of alkylphenol and ethoxylated sorbitan ester 1836 supplemented samples were 12.3 and 12.0% v/v, respectively.Mention of brand or firm names does not constitute an endorsement by University of Illinois or USDA above others of similar nature not mentioned     

Improving the corn-ethanol industry: studying protein separation techniques to obtain higher value-added product options for distillers grains

Currently in America the biofuel ethanol is primarily being produced by the dry grind technique to obtain the starch contained in the corn grains and subsequently subjected to fermentation. This so-called 1st generation technology has two setbacks; first the lingering debate whether its life cycle contributes to a reduction of fossil fuels and the animal feed sectors future supply/demand imbalance caused by the co-product dry distillers grains (DDGS). Additional utilization of the cellulosic components and separation of the proteins for use as chemical precursors have the potential to alleviate both setbacks. Several different corn feedstock layouts were treated with 2nd generation ammonia fiber expansion (AFEX) pre-treatment technology and tested for protein separation options (protease solubilization). The resulting system has the potential to greatly improve ethanol yields with lower bioprocessing energy costs and satisfy a significant portion of the organic chemical industry.     

Evaluation of value-added components of dried distiller's grain with solubles from triticale and wheat

This study focused on the detection of value-added co-products in dried distiller’s grain plus soluble (DDGS), a possibility that could open new avenues for further processing and marketing of DDGS and improving economic sustainability of ethanol industry. Varieties of triticale, wheat and two benchmarks, CPS wheat and Pioneer Hi-Bred corn, were fermented using two very high gravity (VHG) fermentation approaches: jet-cooking and raw starch processing (STARGEN fermentation). DDGS from STARGEN fermentation could be promising sources of value-added co-products. Pronghorn triticale DDGS (STARGEN fermentation) had the highest concentration of sterols (3.7 mg/g), phenolic compounds (13.61 mg GAE/g), and β-glucan (2.07%). CDC Ptarmigan DDGS (STARGEN fermentation) had the highest concentration of tocopherols and tocotrienols (107.0 μg/g), 1.93% of β-glucan, and 53.0 mg/g of fatty acids. AC Reed DDGS (STARGEN method) showed 1.97% of β-glucan. This study shows that proper choice of fermentation approach and feedstock for ethanol production could improve commercial quality of DDGS.     

Ethanolic fermentation of hydrolysates from ammonia fiber expansion (AFEX) treated corn stover and distillers grain without detoxification and external nutrient supplementation

External nutrient supplementation and detoxification of hydrolysate significantly increase the production cost of cellulosic ethanol. In this study, we investigated the feasibility of fermenting cellulosic hydrolysates without washing, detoxification or external nutrient supplementation using ethanologens Escherichia coli KO11 and the adapted strain ML01 at low initial cell density (16 mg dry weight/L). The cellulosic hydrolysates were derived from enzymatically digested ammonia fiber expansion (AFEX)-treated corn stover and dry distiller's grain and solubles (DDGS) at high solids loading (18% by weight). The adaptation was achieved through selective evolution of KO11 on hydrolysate from AFEX-treated corn stover. All cellulosic hydrolysates tested (36-52 g/L glucose) were fermentable. Regardless of strains, metabolic ethanol yields were near the theoretical limit (0.51 g ethanol/g consumed sugar). Volumetric ethanol productivity of 1.2 g/h/L was achieved in fermentation on DDGS hydrolysate and DDGS improved the fermentability of hydrolysate from corn stover. However, enzymatic hydrolysis and xylose utilization during fermentation were the bottlenecks for ethanol production from corn stover at these experimental conditions. In conclusion, fermentation under the baseline conditions was feasible. Utilization of nutrient-rich feedstocks such as DDGS in fermentation can replace expensive media supplementation.     

Water solubilization of DDGS via derivatization with phosphite esters

Ethanol production from corn starch in the corn dry milling process leaves Distillers' Dry Grains and Solubles (DDGS) as a major by-product from which additional ethanol may be economically obtained from its glucan content. A challenge in processing the cellulose content of this material lies in its extensive inter-cellulose chain hydrogen bonding, which inhibits access of enzymes capable of cleaving glycosidic bonds, a transformation required for providing fermentable sugars. The phosphitylation of cellulosic OH groups using a reactive bicyclic phosphite ester is utilized to disrupt cellulosic hydrogen bonds, thus providing access to cellulose chains for further processing. We describe a method of pretreating DDGS with commercially available trimethylolpropane phosphite [P(OCH2)3CEt] in the presence of a slight molar excess of water to afford greater than 90% DDGS solubility in the reaction mixture in methanol and in water. Preliminary results using a model compound [D-(+)-permethylated cellobiose] indicate that glycosidic bonds are cleaved as a consequence of this pretreatment.     

Economic analysis of a modified dry grind ethanol process with recycle of pretreated and enzymatically hydrolyzed distillers' grains

A modification of the conventional dry grind process for producing ethanol from yellow dent corn is considered with respect to its economic value. Process modifications include recycling distillers' grains, after being pretreated and hydrolyzed, with the ground corn and water to go through fermentation again and increase ethanol yields from the corn starch. A dry grind financial model, which has been validated against other financial models in the industry, is utilized to determine the financial impact of the process changes. The hypothesis was that the enhanced process would yield higher revenues through additional ethanol sales, and higher valued dried distillers' grains (DDGS), due to its higher protein content, to mitigate the drop in DDGS yields. A 32% increase in net present value (NPV) for the overall operation is expected when applying the process modifications to a 100million gallon ethanol plant, and an enzyme cost of $0.20 for each additional gallon of ethanol produced. However, there may be no value added to the enhanced dried distillers' grains (eDDGS), even in light of its higher protein levels, as current pricing is expected to be more sensitive to the amino acid profile than the total protein level, and the eDDGS has lower lysine levels, a key amino acid. Thus, there is a decrease in revenue from eDDGS due to the combination of no price change and loss of DDGS yield to ethanol. The financial improvements are a result of the increased revenue from higher ethanol yields outpacing the sum of all added costs, which include higher capital costs, larger loan payments, increased operating costs, and decreased revenues from dried distillers' grains.     

Modeling the effects of pelleting on the logistics of distillers grains shipping

The energy security needs of energy importing nations continue to escalate. It is clear that biofuels can help meet some of the increasing need for energy. Theoretically, these can be produced from a variety of biological materials, including agricultural residues (such as corn stover and wheat straw), perennial grasses, legumes, algae, and other biological materials. Currently, however, the most heavily utilized material is corn starch. Industrial fuel ethanol production in the US primarily uses corn, because it is readily converted into fuel at a relatively low cost compared to other biomass sources. The production of corn-based ethanol in the US is dramatically increasing. As the industry continues to grow, the amount of byproducts and coproducts also increases. At the moment, the nonfermentable residues (which are dried and sold as distillers dried grains with solubles – DDGS) are utilized only as livestock feed. The sale of coproducts provides ethanol processors with a substantial revenue source and significantly increases the profitability of the production process. Even though these materials are used to feed animals in local markets, as the size and scope of the industry continues to grow, the need to ship large quantities of coproducts grows as well. This includes both domestic as well as international transportation. Value-added processing options offer the potential to increase the sustainability of each ethanol plant, and thus the industry overall. However, implementation of new technologies will be dependent upon how their costs interact with current processing costs and the logistics of coproduct deliveries. The objective of this study was to examine some of these issues by developing a computer model to determine potential cost ramifications of using various alternative technologies during ethanol processing. This paper focuses specifically on adding a densification unit operation (i.e., pelleting) to produce value-added DDGS at a fuel ethanol manufacturing plant. We have examined the economic implications of pelleting DDGS for varying DDGS production rates (100–1000 tons/d) and pelleting rates (0–100%), for a series of DDGS sales prices ($50–$200/ton). As the proportion of pelleting increases, the cost of transporting DDGS to distant markets drastically declines, because the rail cars can be filled to capacity. For example, at a DDGS sales price of $50/ton, 100% pelleting will reduce shipping costs (both direct and indirect) by 89% compared to shipping the DDGS in bulk form (i.e., no pelleting), whereas at a DDGS sales price of $200/ton, it will reduce costs by over 96%. It is clear that the sustainability of the ethanol industry can be improved by implementing pelleting technology for the coproducts, especially at those plants that ship their DDGS via rail.     

Corn fiber as a raw material for hemicellulose and ethanol production

Corn fiber (CF) is a potential raw material for the production of various products because it is widely available in corn-producing countries. Corn fiber is a byproduct of the corn wet-milling industry and a very large amount of it (approximately 130 t/day) is produced in Hungary. The major component of corn fiber is the pericarp that consists of 35% hemicellulose, 18% cellulose and 20% remaining starch (protein, fiber oil and lignin are also present in this material). Corn fiber is presently used as animal feed. However, with continuous growth in corn processing to ethanol, there might be problems with the utilization of the surplus fibrous byproducts. In this paper the conversion of corn fiber to ethanol or other products was examined. Destarched corn fiber was pretreated by using different alkaline solutions and dissolved hemicellulose was precipitated with ethanol for the recovery of a valuable coproduct. The residual material consisting mostly of cellulose was hydrolyzed with cellulolytic enzymes and fermented into ethanol by using Saccharomyces cerevisiae.     

Microscopic analysis of corn fiber using starch- and cellulose-specific molecular probes

Ethanol is the primary liquid transportation fuel produced from renewable feedstocks in the United States today. The majority of corn grain, the primary feedstock for ethanol production, has been historically processed in wet mills yielding products such as gluten feed, gluten meal, starch, and germ. Starch extracted from the grain is used to produce ethanol in saccharification and fermentation steps; however the extraction of starch is not 100% efficient. To better understand starch extraction during the wet milling process, we have developed fluorescent probes that can be used to visually localize starch and cellulose in samples using confocal microscopy. These probes are based on the binding specificities of two types of carbohydrate binding modules (CBMs), which are small substrate-specific protein domains derived from carbohydrate degrading enzymes. CBMs were fused, using molecular cloning techniques, to a green fluorescent protein (GFP) or to the red fluorescent protein DsRed (RFP). Using these engineered probes, we found that the binding of the starch-specific probe correlates with starch content in corn fiber samples. We also demonstrate that there is starch internally localized in the endosperm that may contribute to the high starch content in corn fiber. We also surprisingly found that the cellulose-specific probe did not bind to most corn fiber samples, but only to corn fiber that had been hydrolyzed using a thermochemical process that removes the residual starch and much of the hemicellulose. Our findings should be of interest to those working to increase the efficiency of the corn grain to ethanol process.     

玉米灵芝菌粮营养成分及加工特性变化研究

玉米作为主要的杂粮谷物,营养价值高,维生素、膳食纤维等含量丰富,可以预防多种亚健康疾病,受到市场追捧。但是玉米粉营养结构不均衡、加工性差,限制其应用。有研究表明,微生物发酵技术可以改善谷物的营养成分、大分子物质结构和加工特性。基于此,利用灵芝固态发酵玉米,得到玉米灵芝菌粮（简称菌粮）,从营养成分、大分子物质结构和加工特性3个方面对其进行评价。结果显示,与未发酵玉米相比,菌粮中碳水化合物、蛋白质含量分别提高了748%、28.00%,且蛋白质的氨基酸评分提高,而脂肪含量降低了52.56%;维生素C、核黄素和烟酸含量均显著提高（P<0.05）,分别提高了56.19%、73.91%和20.27%,且玉米中缺乏的硫胺素在菌粮中被检测到;菌粮中各类淀粉和纤维的含量也发生了显著变化（P<0.05）,淀粉、支链淀粉含量分别降低了11.17%、34.70%,直链淀粉含量提高了26.66%,粗纤维、不溶性膳食纤维含量分别降低了21.07%、21.47%,可溶性膳食纤维含量提高了13.57%;菌粮粉粘度降低,水溶性指数提高,吸水性指数和溶胀力降低;此外,与灵芝子实体相比,菌粮中灵芝三萜和灵芝酸含量均显著提高（P<0.05）,分别为灵芝子实体的1.68和2.07倍。灵芝固态发酵玉米得到的玉米灵芝菌粮,营养结构更加均衡,功能活性提高,具有更高的营养价值;大分子物质结构发生改变,加工特性得到改善,冲调特性更好。研究结果为食用菌发酵改良谷物特性的研究提供了参考和指导。     

Survival of Escherichia coli O157:H7 in ruminal or fecal contents incubated with corn or wheat dried distillers' grains with solubles

Dried distillers' grain with solubles (DDGS) is a by-product of ethanol production, and its use as cattle feed has increased as a result of the expansion of the fuel ethanol industry. However, the inclusion of corn DDGS into feedlot diets may increase the shedding of Escherichia coli O157:H7. This study investigated whether corn or wheat DDGS at 2 concentrations (20% or 40% vs. 100% barley grain) affected the survival of E.?coli O157:H7 in incubations of ruminal digesta and feces. Neither the type nor the level of DDGS had any effect on fermentation or the survival of E. coli O157:H7 in ruminal digesta. However, there was a time by DDGS interaction (p?< 0.05), where the numbers of E.?coli O157:H7 in feces did not differ after 4 or 12?h of incubation but were greater after 24?h in both 40% wheat and 40% corn DDGS as compared with other treatments. Additionally, after 24?h, the numbers of E. coli O157:H7 were greater in fecal incubations with corn DDGS than with wheat DDGS (p?< 0.05). The differences in the numbers of E.?coli O157:H7 were not attributable to changes in pH or in concentrations of volatile fatty acids in the media. These results suggest that the inclusion of high levels of corn or wheat DDGS in feedlot diets of cattle may encourage the survival of E. coli O157:H7 in feces.     

Effects of conjugated linoleic acid or betaine on the growth performance and fatty acid composition in backfat and belly fat of finishing pigs fed dried distillers grains with solubles

The objectives of this study were to determine the effects of conjugated linoleic acid (CLA) or betaine on the growth performance, carcass characteristics and fatty acid composition in backfat and belly fat of pigs fed distillers dried grains with solubles (DDGS). Thirty-two (60±2 kg) crossbred barrows (Duroc×Landrace×Yorkshine) were assigned to one of four diets randomly: (1) the control diet containing no corn DDGS (control group); (2) the diet containing 30% corn DDGS (DDGS-fed group); (3) the diet containing 30% corn DDGS and 10 g/kg CLA (CLA-fed group); (4) the diet containing 30% corn DDGS and 1 g/kg BET (BET-fed group). The pigs fed DDGS showed that the percentages of C18:2, polyunsaturated fatty acid (PUFA) and iodine value (IV) increased, while C18:1, saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA) decreased. Pigs fed the DDGS+CLA or DDGS+betaine diets showed the increased percentage of SFA, and the decreased percentage of C18:2, PUFA and IV. In conclusion, results confirmed that the diets containing 30% DDGS had no detrimental effects on growth performance, but increased the percentage of PUFA and IV and decreased the percentage of SFA and MUFA in the backfat and belly fat. However, supplementation with CLA or BET can part reverse these effects on carcass fat in finishing pigs.     

Composition of corn dry-grind ethanol by-products: DDGS, wet cake, and thin stillage

DDGS and wet distillers' grains are the major co-products of the dry grind ethanol facilities. As they are mainly used as animal feed, a typical compositional analysis of the DDGS and wet distillers' grains mainly focuses on defining the feedstock's nutritional characteristics. With an increasing demand for fuel ethanol, the DDGS and wet distillers' grains are viewed as a potential bridge feedstock for ethanol production from other cellulosic biomass. The introduction of DDGS or wet distillers' grains as an additional feed to the existing dry grind plants for increased ethanol yield requires a different approach to the compositional analysis of the material. Rather than focusing on its nutritional value, this new approach aims at determining more detailed chemical composition, especially on polymeric sugars such as cellulose, starch and xylan, which release fermentable sugars upon enzymatic hydrolysis. In this paper we present a detailed and complete compositional analysis procedure suggested for DDGS and wet distillers' grains, as well as the resulting compositions completed by three different research groups. Polymeric sugars, crude protein, crude oil and ash contents of DDGS and wet distillers' grains were accurately and reproducibly determined by the compositional analysis procedure described in this paper.     

Enzyme characterization for hydrolysis of AFEX and liquid hot-water pretreated distillers' grains and their conversion to ethanol

Dried distillers' grains with solubles (DDGS), a co-product of corn ethanol production, was investigated as a feedstock for additional ethanol production. DDGS was pretreated with liquid hot-water (LHW) and ammonia fiber explosion (AFEX) processes. Cellulose was readily converted to glucose from both LHW and AFEX treated DDGS using a mixture of commercial cellulase and beta-glucosidase; however, these enzymes were ineffective at saccharifying the xylan present in the pretreated DDGS. Several commercial enzyme preparations were evaluated in combination with cellulase to saccharify pretreated DDGS xylan and it was found that adding commercial grade (e.g. impure) pectinase and feruloyl esterase (FAE) preparations were effective at releasing arabinose and xylose. The response of sugar yields for pretreated AFEX and LHW DDGS (6wt%/solids) were determined for different enzyme loadings of FAE and pectinase and modeled as a response surfaces. Arabinose and xylose yields rose with increasing FAE and pectinase enzyme dosages for both pretreated materials. When hydrolyzed at 20wt%/solids with the same blend of commercial enzymes, the yields were 278 and 261g sugars (i.e. total of arabinose, xylose, and glucose) per kg of DDGS (dry basis, db) for AFEX and LHW pretreated DDGS, respectively. The pretreated DDGS's were also evaluated for fermentation using Saccharomyces cerevisiae at 15wt%/solids. Pretreated DDGS were readily fermented and were converted to ethanol at 89-90% efficiency based upon total glucans; S. cerevisiae does not ferment arabinose or xylose.     

Feeding dried distillers grains with solubles to lactating beef cows: impact of excess protein and fat on post-weaning progeny growth,glucose tolerance and carcass traits

Feeding dried distillers grains with solubles (DDGS), a feed high in fat and protein, to lactating beef cows can alter milk production and composition, resulting in improved pre-weaning growth of progeny. This alteration in milk profile may consequently alter the growth and carcass composition of the offspring after weaning. Therefore, Angus×Simmental steers (n=48) whose dams were fed one of two diets supplemented with either DDGS or soybean meal (CON) from calving to mid-lactation were placed in a feedlot to determine the effects of maternal nutrition during lactation on progeny development and carcass composition. Cow–calf pairs were allotted to two treatments at birth based on cow and calf BW, breed and age. Maternal diets were isocaloric (3.97 MJ/kg NE_g) and consisted of rye hay supplemented with DDGS at 1% of BW (19.4% CP; 8.76% fat) or rye hay and corn silage supplemented with CON (11.7% CP; 2.06% fat). After conclusion of the treatments at 129 days postpartum, cow–calf pairs were comingled and managed as one group until weaning at 219 days postpartum. Steers were then transitioned to a common diet composed of 60% DDGS, 34% corn silage and 6% vitamin/mineral supplement and were placed indoors in individual pens with slatted floors. An intravenous glucose tolerance test (IVGTT) was performed 134 days after feedlot entry on 16 steers (CON, n=7; DDGS, n=9) to determine the effect of maternal diet on glucose and insulin sensitivity. Steers were slaughtered at a target BW of 645 kg. Categorical and continuous data were analyzed using the GLIMMIX and MIXED procedures of SAS, respectively. Steers from DDGS dams tended to be heavier on day 85 of feedlot finishing (P=0.09) compared with steers from CON dams. However, there were no differences in final weight, average daily gain, dry matter intake or efficiency (gain:feed, P⩾0.18). Maternal treatments did not affect progeny days on feed (P=0.15), despite a mean difference of 9 days in favor of DDGS. Glucose and insulin concentrations and area under the curve of progeny as measured by IVGTT were not affected by maternal diet (P⩾0.16). Maternal DDGS supplementation decreased marbling score (P=0.04), but did not influence carcass grading percentage or any other carcass characteristic (P⩾0.17).