Reducing Energy Costs in Ethanol Production Through Improved On-Farm Methods

Grant: 06-02
Principal Investigator: Daniel Loy
Organization: Iowa State University
Technical Area: Efficiency & Renewable Energy

The ethanol industry is rapidly expanding nationally and Iowa is the center of this expansion. According to the surveys published periodically by the Renewable Fuels Association (RFA, 2 005) the ethanol industry produced 3.4 billion gallons of ethanol in 2004. Of this, 864 million gallons were produced in Iowa (25.4%). Currently, 1.15 billion gallons of annual capacity are under construction nationally with 465 million gallons of this capacity in Iowa (41% of the national expansion). The current expansion is expected to be nearly 8 billion gallons nationally by 2012. Assuming that one bushel of corn produces 2.7 gallons of ethanol then it is anticipated that ethanol production alone will consume nearly 3 billion bushels of the US corn crop each year. If 18 pounds of dried distillers grains are produced per bushel (Tiffany and Eidman, 2003), then the production of distillers grains will swell to approximately 10 million tons. Historically, distillers grains have been dried and exported as a global commodity. As much as 40% of the energy and 50% of the natural gas associated with the production of ethanol is in the drying of the feed coproducts (Coltran, 2004).

In the 2004 survey of ethanol plants (USDA, 2004), about one-half of the responding plants produced wet distillers grains, 100% utilized rail transportation and 67% used trucks. When paid by the plant, the average distance hauled was 1,550 miles for rail, at a cost of $30 per ton, and 82 miles for truck at a cost of $4 per ton. Of the plants producing wet distillers grains, 100% utilized truck transportation at an average delivery distance of 61 miles and a cost of $4 per ton. The average moisture content of the wet feeds was approximately 60%; therefore the transportation cost of the wet feeds per unit of dry material is almost double per mile. Because of the cost of transporting water, wet distillers feeds tend to be utilized locally.

In a 2005 survey of Iowa beef producers (Lawrence and Schuknecht, 2005), 70.8% of Iowa feedlots reported using corn coproducts in their rations. The majority of these were high moisture feeds that were transported an average of 69 miles. This is consistent with the 61 miles reported in the ethanol plant survey. Wet distillers grains have a short shelf life, particularly in warm weather. Depending on the time of the year, 4 to 10 days is a typical time period before significant mold and fungal growth occurs in storage. Still, larger feedlots have sufficient size and volume to utilize the minimal purchase quantity in that time period. In the Iowa beef producer survey previously mentioned, only 28% of the cow calf producers utilized corn coproducts. Storage issues were the primary issue limited the use of these products. The average size of cow calf producers was approximately 150 cows, while the average feedlot was over 1700 head. To expand the use of wet distillers feeds to medium to small sized feedlots practically, longer-term storage methods are required. Organic acids can be added to the wet coproducts to increase shelf life, but at a significant cost. In many of these operations low cost forages, such as corn stover and low quality hay, could be utilized if properly supplemented with distillers feeds (Loy et al, 2005). Practical on farm approaches would require bagging or ensiling with other feeds (Kalscheur and Garcia, 2004). In 2004, the Iowa Beef Center conducted a simple on-farm demonstration of long-term storage of a mixture including tub ground corn stalks (stover) and high moisture condensed distiller’s solubles. Observations made included nutrient analysis in and out of storage (about 2 months) and visual observation of the palatability of the combined product. Results were very encouraging, but highly subjective. Comparisons of animal performance and storage losses could not be accomplished.

Project Objectives 1. Evaluate animal performance, storage losses and feasibility cost of ensiling a mixture of tub ground low quality hay and condensed distillers solubles for growing cattle. 2. Demonstrate the feasibility, animal productivity, cost and economics of long term storage and feeding of wet distillers grains in a cow calf operation. 3. Demonstrate the feasibility, animal productivity, cost and economics of long term storage and feeding of wet distillers grains in an ewe flock operation. 4. Disseminate results through factsheets, press releases, field days, and the Iowa Beef Center website.

Work to Date (Technical Report – April 2006)

Objective 1: Eight tons of corn condensed distillers solubles were mixed with an equal amount of tub ground fescue hay on September 15, 2006.  The mixed material was placed in a bunker silo at the ISU Beef Nutrition Farm, packed with a tractor and covered with plastic.  Samples were taken of the solubles, hay and mixture and submitted for nutrient analysis.  Eight additional tons of corn condensed distillers solubles was stored in a tank.  The mixture was compared to mixing the same feeds daily and a conventional corn-corn silage-hay diet. Fifty four calves were fed in 9 pens (3 pens per treatment).  Cattle were purchased and were on trial October 23, 2006.  The cattle were fed for 85 days and the final weights were collected on January 16, 2007. The calves weighed 597 pounds on average at the beginning of the study.  After 56 days, 40% corn (dry matter basis) was added to all three diets to evaluate compensatory gain.  The bunker mixture was dryer than ideal for optimum packing, oxygen exclusion and ultimately feed preservation.  Some mold and out of condition feed developed.  While intake of the preserved forage mixture was normal, daily gains were poorer than the same feeds mixed daily.  This suggests that some of the energy value of the feed was depleted in storage.  The solubles stored in a tank in liquid form and mixed with the forage daily performed similarly to the controls.  These observations are based on preliminary interpretation of the data.  Statistical analysis is yet to be performed.  The storage loss of the hay-solubles mixture was 8.5%.

Objective 2: The method of storage for the wet distillers grains ground hay mix proved to be very effective with 7.4% storage and feeding loss.  A 80/20 blend proved to work well in the storage bag and was eagerly and readily consumed with little to no waste by a large number of fall calving, mature, lactating Angus females.  Developing heifer gains on higher levels of modified distillers grains are encouraging at this point, however, it is imperative that conclusion not be drawn until reproductive rates are observed and analyzed.

Objective 3: Two trials were conducted at McNay Research Farm to evaluate the use of modified distillers in ewe wintering rations.  Ewes were fed a diet of 50% modified distillers and 50% chopped corn stalks on an as fed basis.  Ewes were offered 4.2 pounds per day.  Initially, some ewes did not readily consume this diet.  This was a short term (<5 days).  Ewes performed equal to control ewes being fed three pounds of high quality hay.  The diet of modified distillers and corn stalks were mixed in weekly batches. The ration looked excellent the first three days but became fuzzy before it was all consumed at the end of seven days.  Five out of 36 ewes developed problems with listeriosis in week four of the feeding trial.  Weather conditions were much above normal in late November through early December which increased mold growth drastically on the mixed pile.

Feed samples were submitted to the veterinary diagnostic lab for listeria confirmation.  Listeria was found in the mixed feed, modified distillers stored in a tube since mid-October and corn stalks.  So we are not really sure were the listeria came from. This trial demonstrates that wet distillers may create problems in ewe rations when stored for several days.  Unless producers can insure fresh wet disillers (<2 days) they should probably use distillers in their ewe rations.

Objective 4: Feed storage of wet distillers’ co products is a topic of considerable interest among livestock producers.  In the course of educating producers through the authors’ extension efforts, awareness of this project has been made to those producers. A field day for beef producers was held at the McNay research farm for beef and sheep producers where preliminary results of the study were shared.  Also, this information will be shared with Veterinarians in a meeting on May 16 and with Extension Beef specialists on May 17, 2007 at the McNay research farm.  Information about the studies was shared at Iowa Beef Center ethanol co product feeding meetings throughout the fall and winter. Sixty four meetings were conducted and they were attended by 2955 people.