News Releases

Allen Trenkle, Charles F. Curtiss Distinguished Professor of Agriculture, has been researching the use of corn milling co-products in livestock rations for more than 20 years. Many others at Iowa State University also are working in this area. Here's a sampling of recent research and extension work on the use of distillers grains.

Evaluating the effects of feeding distillers grains on meat quality — Most experiments with distillers feeds have been designed to measure the nutritional value of the product without considering any effects on carcass quality. Recently four studies where cattle were fed up to 40 percent distillers grains were reviewed and summarized to check for meat quality. There was some reduction in marbling at the high levels, but the net value of the carcasses in a typical grid market was not greatly different. Taste panel analysis of tenderness, juiciness and flavor was not changed. (Allen Trenkle, animal science)

Using ethanol co-products in forage-based beef systems — The Leopold Center for Sustainable Agriculture provided $52,000 for a three-year demonstration project. The objective is to evaluate the feeding of various corn co-products in cow-calf grazing operations. On-farm demonstrations at two southern Iowa farms were conducted in 2006. A demonstration in Lucas County involved three herds — a control with no supplementation, a group fed 12 pounds every other day of wet distillers grains with solubles, and a group fed 6 pounds every other day of a 50/50 pellet with DDGS and soybean hulls. Cows in all groups maintained body condition scores through weaning. A demonstration in Union County involved two herds — a control group and a group receiving five pounds of a DDGS-based cube fed every other day. Calf weight per day of age was higher on the control group compared to the supplemented group, perhaps due to higher prevalence of fescue. Similar feeding trials will begin in 2007 at the ISU McNay Research and Demonstration Farm near Chariton and will include treatments with higher feeding levels of co-products, and stocking rate adjustments based on level of supplementation. (Dan Loy, animal science; Joe Sellers, Extension)

Distillers grains in an integrated pasture and drylot system for feedlot steers — Many new ethanol plants produce significant amounts of condensed distillers solubles. The liquid fraction is often condensed to syrup, which is commonly referred to as condensed corn distillers solubles (CCDS). The objective of this three-year study at the ISU Western Iowa Research and Demonstration Farm at Castana was to evaluate the use of CCDS mixed with ground corn stalks in a pasture and drylot growing-finishing program. Each year 112 calves were placed either in drylot or on bromegrass pasture. The calves were randomly assigned to four treatments. Pastured cattle receiving CCDS gained a half-pound per day more than cattle not receiving CCDS. Average carcass weights and yield and quality grades were similar. Although cattle receiving corn stalks and CCDS in place of alfalfa hay gained somewhat slower overall, they also consumed slightly less daily dry matter. (Peter Hoffman, animal science)

Use of distillers grains in beef cows grazing corn stalks — Each fall, corn stalk grazing is used by many Iowa cow-calf producers. Extending this grazing period would help producers lower their total annual feed cost. In a demonstration project at the ISU Beef Nutrition farm near Ames, 67 purebred Angus and Simmental cows averaging 1,450 lbs were supplemented with modified distillers grains with solubles (MDGS) while grazing cornstalks in October and November. Using a supplementation schedule of Monday, Wednesday and Friday, cows were fed an average of 16.3 pounds of MDGS or 9 pounds of dry matter at each feeding. The cows maintained body weight and condition score during the 41-day project, which shows distillers grains can be used to supplement grazing cows to meet their protein and energy needs. (Daryl Strohbehn, animal science)

Distillers grains for fall-calving cows or calves grazing stockpiled forage — Three feeding treatments were used to test the use of distillers grains on fall-calving cows and calves grazing stockpiled forages. Cow and calf weights and cow body condition were measured over the grazing season. Cows in the group receiving distillers grains as a supplement had less body-weight loss than cows in the other two groups. In the final analysis, it was determined that supplementation of DDG to cows or a DDG-based creep feed for calves increases weight gains of fall-born calves while reducing loss of body condition in cows, and does not affect the rate for forage utilization. (James Russell, animal science)

Finishing beef cattle on grass supplemented with co-products — This study looked at the possibility of feeding beef cattle to market weight by grazing cool-season grass and supplementing with distillers grains in pellet form. The project took place on two ISU research farms in southwest Iowa, and involved both yearling cattle and fall-born calves. At each location, the cattle were divided by weight into one of two groups. One group had immediate access to co-product pellets while the other group didn't receive the pellets until mid- June. The cattle readily consumed the pellets — a blend of DDGs, soy hulls and wheat midds (a co-product of wheat milling) — from self-feeders. The calves that received the pellets from the beginning of the feeding trial grew faster and reached market weight sooner. This project showed that with good grass, yearling steers can be expected to gain 400 to 500 pounds over six months of grazing with co-product feed supplementation. (Mark Honeyman and Dan Morrical, animal science)

DDG feeding and impacts on meat quality — As part of the grazing study in southwest Iowa in which cattle are fed distiller's dried grains in addition to forages, researchers are exploring what, if any, changes occur in meat quality when DDGs are introduced into grass-finished systems. Leopold Center funding of $11,000 will pay for meat quality (fatness, ribeye, marbling) and carcass data to be collected and analyzed. (Mark Honeyman and Dan Morrical, Animal Science)

Performance of finishing steers fed modified wet distillers grains — The objectives of this study were to evaluate modified wet distillers grains (WDGS) as a feed for finishing cattle and to determine the value of replacing corn grain with WDGS when corn prices increase. Preconditioned steer calves weighing 690 pounds were fed diets containing on a dry basis 0, 25 and 47 percent modified WDGS for 186 days. Daily gains were not statistically different among diets. Steers fed 47 percent WDGS consumed less feed and tended to be more efficient. There were no statistically significant differences in carcass weight, backfat, ribeye area, marbling score or yield grade. An economic analysis indicated high levels of WDGS should not be fed when it is priced equal to corn, but up to 47 percent of the total feed intake of finishing cattle can be derived from modified WDGS when it is priced at 75 percent or less than the price of corn. When corn prices are greater than $3 per bushel, savings in feed cost can be greater than $50 per head if the WDGS are priced at 75 percent or less of the price of corn. (Allen Trenkle, animal science)

Using wet distillers grains in cattle diets without corn — The objective of this study was to evaluate modified wet distillers grains (WDGS) as a feed for supplementing lower quality grass hay or corn stalks when fed to growing and finishing steers. Two experiments were conducted. In a 112-day study, performance of steers fed grass hay supplemented with WDGS or a mixture of corn and DGS was superior to calves fed corn silage. In a second project, steer calves weighing 690 pounds were fed a typical corn-based finishing diet for 186 days or a diet of tub-ground corn stalks supplemented with modified WDGS for 210 days. Steers fed the stover-DGS diet did not gain as well as steers fed the corn-based diet and produced fewer USDA Choice grading carcasses. Results of these two studies indicate modified WDGS is a suitable supplement for mid to lower quality roughages for feeding cattle and it is possible to produce acceptable grading beef without grain. However, for such programs to be financially successful, the price of DGS relative to corn and the final weight of the cattle are important considerations. (Allen Trenkle, animal science)

On-farm storage of high moisture distillers grains — To expand the use of wet distillers feeds, longer-term storage methods are needed. A $25,000 grant from the Iowa Energy Center is funding a project that began in October 2006. Silo-bags containing modified distillers grains and wet distillers grains with ground hay were filled at the ISU McNay Research Farm. The products are being fed to beef cows, heifers and ewes and compared to the feeding of a conventional corn-corn silage-hay diet. The hope is that through better storage methods small beef producers can capitalize on the cost effectiveness of ethanol co-products, reducing their own costs of production while reducing energy use in the production of ethanol. (Dan Loy, animal science)

Feeding distillers grains to pigs — While the majority of the research on feeding DDGs deals with cattle, a new project at the ISU Western Research and Demonstration farm near Castana is looking at feeding DDG pellets to pigs in hoop barns. Previous studies have shown it's possible to feed 10 percent DDGs in a swine ration, but this new project will be considering 20 and 40 percent inclusion rates. Pretrial results are positive, although one problem identified is that feed consumption decreases at higher DDG levels. Another problem identified in other projects is that the higher levels of corn oil in DDGs can mean a reduction in meat quality. So this project will include carcass data collection and meat quality evaluations. (Mark Honeyman, animal science; Dave Stender, ISU Extension)

Feeding distillers grains to poultry decreases ammonia emissions — In a recent project, researchers found that increasing the content of dietary fiber in the feed of laying hens can lower manure ammonia emissions by 40 percent per hen without adversely affecting egg production. The project involved feeding 256 hens fed one of four types of diets. There was a standard corn-soybean meal control diet, plus three experimental diets that included corn distillers dried grains with solubles (DDGS), wheat midds or soybean hulls. All three fiber diets resulted in lower ammonia emissions, but researchers are particularly interested in the opportunities offered by DDGS. Hens fed the fiber diets did not excrete more manure than hens fed the control diet, and egg production and egg mass were not affected. Feed consumption did increase by 2 percent for hens fed the corn DDGS or soybean hulls diets, but the researchers found this effect can be remedied by using more accurate energy values for corn DDGS and soybean hulls. This study is currently being repeated in a commercial setting involving more than 400,000 laying hens fed either zero or 15 percent corn DDGS. (Kristjan Bregendahl, animal science)

Is phosphorus a problem when feeding distillers grains? — Fermenting the starch in corn to ethanol concentrates phosphorus in distillers grains about three times. Concern has been expressed that feeding distillers grains will result in overfeeding phosphorus and increase its concentration in manure, causing an environmental problem. Equations from the National Research Council's Nutrient Requirements of Beef Cattle were used to predict phosphorus retention and excretion of finishing cattle growing at different rates and different stages of maturity on a farm with a simulated 1,000 head feedlot. Calculations show that if the feedlot is located on the farm from which all the feed is harvested and concentrations of phosphorus in the soils are adequate but not excessive, manure from the feedlot would not replace all the phosphorus removed by the corn crop needed to feed the cattle and produce the grain for ethanol. This project indicates feeding distillers grains would not cause an environmental problem, but does require each feedlot to develop manure management plans. (Allen Trenkle, animal science)

A feedlot cattle calculator to assist with phosphorus and nitrogen excretion — Personnel at the Iowa Beef Center worked with the Iowa Renewable Fuels Association, Iowa Cattlemen's Association, Iowa Department of Natural Resources and Natural Resources Conservation Service to develop management tools, and conducted meetings to educate ethanol plants, agribusiness nutritionists, agronomists and producers about managing the higher phosphorous concentrations in DGS. A feedlot cattle phosphorus and nitrogen excretion calculator was developed to help estimate manure nutrient implications of feeding distillers grains. It is available online.

Increasing the use of co-products — There has been significant outreach activity on the use of ethanol co-products, including conferences and publications. A few examples:

• Growing Iowa’s Cattle Industry: Ethanol, Opportunities, and Economic Development conference June 5, 2006. Presentations can be viewed online.
• There are four extension publications available on distillers grains. These and many other resources on this topic are available from the Iowa Beef Center.
• The Iowa Pork Industry Center also has a special section on ethanol co-products. A new fact sheet on feeding distillers grains to swine is being developed and will be posted soon.
• Feeding Ethanol Co-products to Beef Cattle newsletter. The first in a series was published in December and is available online.