Economic Research on Ethanol Feed-Use Coproducts: A Review, Synthesis, and Path Forward

During the mid-2000s to the early 2010s, the domestic ethanol industry witnessed substantial growth, with ethanol coproducts emerging as vital elements for plant profitability and livestock feeding. Initially serving as supplementary revenue streams, coproducts from ethanol production have evolved into diverse value-added offerings, bolstering revenue streams, and sustaining profit margins. This study reviews existing economic research on ethanol coproducts, detailing methodologies, product focus, and research locations. Initially gathering 972 articles from 9 databases, 110 articles were synthesized. We find that most studies primarily examined the growth and future of the ethanol industry with a limited focus on specific coproducts. Feed-use distillers’ grains, especially dried distillers’ grains, were the most widely published while newer coproducts like pelletized, deoiled, and high-protein distillers’ grains were relatively understudied. Non-feed-use products were notably overlooked, highlighting the need for exploration beyond conventional applications. The evolving market landscape for ethanol co-products has surpassed published academic understanding of the economic tradeoffs necessitating further research into product dynamics, pricing, marketing, market structures, and regulatory frameworks. This highlights and underscores the importance of investigating value-added grains across diverse commodities and geographic contexts to inform strategic decision-making and policy formulation

Evaluation of the Water Footprint of Beef Cattle Production in Nebraska

Data were compiled on feed usage to model the amount of water needed to produce beef in typical Nebraska production systems. Production systems where cows were wintered on corn residue utilized 18% less water than systems utilizing native range as a wintering source, because of water allocations. Therefore, the water footprint (gallons of water required to produce one pound of boneless meat) was decreased by 18%. In addition, increasing the dietary inclusion of distillers grains from 0% to 40% decreased the water footprint in the finishing phase by 29%, again based on water allocation. Utilizing corn residue and distillers grains in Nebraska beef cattle systems decreases the overall water footprint of production. Additionally, the water footprint of the systems analyzed was 80% green water as rain, minimizing the environmental impact of beef production on freshwater use and ecological water balance

Effects of Urea and Distillers Inclusion in Finishing Diets on Steer Performance and Carcass Characteristics

An experiment was conducted to evaluate the effect of supplemental urea in dry rolled corn based finishing diets containing low inclusions of distillers grains. Treatments were set up in a 3 × 3 factorial arrangement. The first factor was wet distillers inclusion at either 10, 15, or 20% of diet DM. The second factor was urea inclusion at either 0, 0.5, or 1.0% of diet dry matter. Increasing inclusion of distillers linearly improved feed conversion and linearly reduced dry matter intake. An interaction for feed efficiency was observed where there was no effect of added urea when 10% or 20% distillers was fed and a quadratic effect was observed when 15% distillers grains was fed where 0.5% urea appeared to be optimum. Added urea in a finishing diet with 20 or 10% distillers has minimal impact on finishing performance; however, feeding 0.5% urea in a 15% distillers diet may be beneficial

Effect of Adding Urea to Finishing Diets Containing Two Different Inclusions of Distillers Grains on Steer Performance and Carcass Characteristics

The effects of adding urea to a dry rolled corn based finishing diet containing low inclusions of distillers grains was evaluated. Treatments were designed as a 2 × 4 factorial arrangement with factors consisting of wet distillers inclusion (either 12 or 20% of diet DM) and urea inclusion (0, 0.4, 0.8, 1.2% of diet DM). There were no significant interactions observed between distillers inclusion and urea inclusion in the diet. Increasing inclusion of distillers grains improved carcass adjusted average daily gain and feed conversion and reduced dry matter intake. Increasing distillers inclusion also increased 12th rib fat and had a tendency to increase hot carcass weight. There were no significant linear or quadratic responses for increasing urea inclusion in the diet. These data suggest that when feeding at least 12% distillers in the diet, supplemental urea has minimal impact on animal performance

Effect of Crude Glycerin Concentration on Growing Steer Performance in Forage Diets

The effect of increasing crude glycerin concentration was evaluated in a 91- d growing trial utilizing 60 steers. Crude glycerin was included at 0, 4, 8, and 12% of dietary DM in diets consisting of 50% wheat straw; 22.9- 37.0% wet corn bran, and 8.0- 10.1% soybean meal. Crude glycerin replaced wet corn bran and soybean meal was added to maintain dietary CP. Steer ending BW was not different among treatments. Th ere was a quadratic increase in DMI from 0 to 8% crude glycerin and subsequent decrease at 12%. Th ere was no difference in ADG or feed efficiency among crude glycerin concentrations. Therefore, crude glycerin appears to have an energy value slightly less than wet corn bran in a forage- based diet

Relationships of Chute-Side Measurements to Carcass Measurements

Three data sets were compiled to determine the relationship of weight, performance, hip height and ultrasound-measured fat thickness to hot carcass weight and fat thickness. Weight is generally the best predictor of relative differences in carcass weight at any time in the production system. Hip heights do not predict relative differences in carcass weight. Although the combination of hip height and weight is a more precise indicator of carcass weight than is hip height alone, generally this combination is inferior to weight alone. Only ultrasound-measured fat thickness predicted relative differences in fat thickness. Prediction of relative differences in carcass weight from body weight and fat thickness from ultrasound scans improved as marketing date approached

Pooled Analysis of Individually Fed Finishing Trials

A pooled analysis of 21 finishing trials (2002–2016; 1530 animals) with cattle individually fed in Calan gate barns was conducted. Mixed model regression analysis following random coefficient methodology was used to evaluate relationships between performance variables and carcass characteristics. Gain had a greater effect on efficiency (R2 = 0.72) compared to intake (R2 = 0.02). The relationship between gain and efficiency was cubic, while intake had a quadratic relationship. The cubic response of gain relative to efficiency was continually increasing with relatively slight curves in the line heavily influenced by points that lay on the ends of the data. Efficiency also had cubic relationships with fat thickness and marbling of carcasses; however, the regressions had low R2 values of 0.01. There was a significant relationship between efficiency and fat thickness and marbling, but the variation around the trend line was high. Efficiency alone is a poor predictor of fat thickness and marbling

Dried Distillers Grains Supplementation of Calves Grazing Irrigated Corn Residue

Steer calves grazing irrigated corn residue received supplementation of dried distillers grains plus solubles (DGS) at 0.3, 0.5, 0.7, 0.9, or 1.1% of body weight. Steers were individually supplemented daily through Calan gates. Daily gain improved linearly (0.77 lb/head/day to 2.21 lb/head/day) with increasing supplementation (1.5 lb/day to 7 lb/day). Supplementing DGS to calves grazing corn residue increased gain during the winter period

Using a Modified \u3ci\u3eIn-Vitro\u3c/i\u3e Procedure to Measure Corn Bran Buoyancy

An in vitro procedure was modified to estimate rumen buoyancy of corn bran and fiber types. Inoculum was obtained from two beef heifers and mixed with McDougall’s buffer then distributed to the in vitro tubes for 30 hours incubation at 100 °F. Fibrous material formed a matte layer which was measured to describe buoyancy. Tubes contained 6g of a feedlot-type diet with 7.5% fiber type (alfalfa hay, grass hay, corn silage, or corn stalks), with no replacement or 25% replacement of the remaining corn with corn bran. Buoyancy declined over time. Alfalfa hay had the most positive effect on buoyancy of corn bran. This new method offers promise for describing rumen buoyancy

Sorting Strategies for Yearlings

One hundred sixty medium-framed English-cross steers were used in each year of a two-year study to determine effects of three sorting strategies on performance, carcass characteristics and profitability in an extensive beef production system. Sorting by weight before the grazing period or entering the feedlot decreased variation in carcass weight. Sorting by weight before the grazing period increased marbling scores and resulted in significantly higher premiums. However, no sorting strategy significantly increased carcass weight or improved profitability