The search for renewable fuels has spurred revolutionary growth in biodiesel and ethanol production. As a result, the beef industry is scrambling to fill the partial void created by the shift of corn from feed to fuel.

There's some salvation for the cattle industry in using what's left from corn or other grains after the starch is fermented into ethanol. And most reports are that it's symbiotic.

A 2006 study in Minnesota suggested that without the use of ethanol byproducts, or “co-products,” for animal feed, the benefits of ethanol production would be seriously undermined. It was determined that ethanol from corn yields 25% more energy than is required to produce it. However, this positive energy balance was attributed almost entirely to an energy credit for the byproducts yielded by ethanol production.

The report said the energy credit was given because the byproducts offset the production of other commodities such as corn and soybean meal.

Quandaries, questions

Lance Forster, Jr., an Archer Daniels Midland nutritionist, spoke on the impact of ethanol byproducts on U.S. beef quality during the recent International Livestock Congress in Denver. He says the trend in increased availability of ethanol byproducts is unlikely to diminish. In 1998, 2.5 million tons of dried distillers grains (DDGs) were available. The outlook is for 19 million tons to be produced in 2008.

“We expect DDGs production to level off at over 40 million tons by 2018 as ethanol-plant expansion plateaus at around 220 facilities,” Forster says. “Therefore, there's a great deal of discussion on the impact the increased use of distillers grains in both wet and dry forms may have on the quality of beef produced in the U.S.”

For seedstock and cow-calf operators, backgrounders and cattle feeders, the quandary is how to put the ethanol byproducts to the best use. Cheaper than corn and many other livestock feeds, they help cattle producers cope with high feed costs fueled by the ethanol boom.

But swirling around this quandary is the impact this shift will have on the quality of beef fed the byproducts. There are also questions about beef safety — with the ethanol byproducts possibly contributing to a surge in E. coli contamination cases in 2007.

The byproduct of most attention are DDGs, primarily from corn. During the process of converting the starch from corn into ethanol, the remaining nutrients found in the kernel are concentrated three-fold. Thus, DDGs are higher in protein and fat compared to the original grain. Contributions of protein, fat and minerals from yeast cells, as well as supplemental nitrogen and mineral buffers used to promote yeast growth early in the fermentation, add to DDGs' nutrient profile.

“The utilization of the starch by yeast cells also concentrates up the fiber components of corn,” he adds. “This fiber fraction is thoroughly fermentable in the rumen and is part of DDGs' total energy profile for beef cattle.”

Therefore, Forster notes, while non-ruminants can't fully utilize this fraction and aren't able to get as much energy from DDGs, the high energy and protein levels along with the lower starch found in DDGs have made it a staple in many dairy rations for years where the nutrient density of the diet is higher. The increased use of DDGs in diets in replacement of corn also has the initial effect of providing greater amounts of fat and protein while decreasing the amount of starch in the diet.

“Concerns of excess nitrogen and phosphorus in manure, along with rumen upset due to excess fat, all work to limit the inclusion level of DDGs to somewhere below 20% of the diet dry matter,” Forster says.

An economical supplement

Distillers grains (DGs) can be an economical supplement for stocker calves, developing heifers and cows that may need energy supplement in addition to supplemental protein and phosphorus.

Because forage-based protein is highly degraded in the rumen, it should be supplemented with undegraded (bypass) protein to meet metabolizable protein requirements, explains Terry Klopfenstein, University of Nebraska professor of ruminant nutrition.

“DGs (wet or dry) is an excellent source of undegraded protein and phosphorus,” Klopfenstein says. “It's advantageous if the same commodity can be used for supplemental energy as well as protein.”

DGs should have 120% of the energy value of corn grain, he adds. And because DGs contain very little starch, they should not depress fiber digestion.

“We've looked at the formulation and cost of a soybean meal-based supplement and a DGs grains-based supplement,” Klopfenstein adds. “They should have equal feeding value, but the DGs supplement is less expensive because of the high escape value of the protein.”

Research studies indicate high levels of both wet and dry DGs can effectively be fed to finishing cattle.

“Levels approaching 40% of the diet will be used by producers in close proximity to ethanol plants,” Forster says. “Issues regarding excess protein and fat in these rations need to be carefully monitored, and ingredient selection, which is complementary to these, is essential.”

Proper balancing of minerals is essential for utilization of high levels of ethanol byproducts. These include sulfur, phosphorous and magnesium, which can all concentrate up in these feeds. Another is calcium, which needs to be supplemented to balance the calcium:phosphous ratio for proper growth and performance.

But overall, Forster says savings in ration costs, as well as ability to use less corn silage and smaller amounts of additional roughage, will also help increase the acceptance of DGs by the feedlot industry.

“The careful selection of ingredient suppliers is an important consideration in using DGs,” he says. “Variation between ethanol facilities and by processing conditions can affect the nutrient profile of DDGs.”

Attention to the nutrient values that are present in the DGs being used in a ration will help to maximize animal performance.

E. coli O157:H7 examined

As much as the industry may want to think not, there might be a fly in the ethanol ointment. Recent studies suggest ethanol byproducts may make cattle more likely to shed E. coli O157:H7, possibly contributing to the surge in contamination cases in 2007.

In 2007, there were 21 recalls, totaling a record 33.4 million lbs. of beef, according to USDA. In 2006, there were eight recalls involving about 182,000 lbs., and 2005 saw five recalls totaling 1.25 million lbs.

Kansas State University (KSU) researchers reported in the January 2008 Journal of Applied and Environmental Microbiology that cattle fed DGs were more than twice as likely to shed E. coli O157:H7 in their feces than control cattle.

Meanwhile, University of Nebraska research found cattle fed 40-50% DGs had increased rates of E. coli, but cattle fed a diet of 10-30% of the product actually had lower E. coli levels than those on an all-corn diet.

A new KSU study contradicts the earlier KSU research though, concluding that the prevalence of E. coli O157:H7 or salmonella is no different in cattle fed steam-flaked corn and in cattle fed the same ration with 25% DDGs.

“Unlike our previous studies, we found no evidence to indicate that dietary inclusion of DGs or corn-processing methods have a significant effect on the prevalence of E. coli O157:H7 or salmonella in cattle feces,” KSU researchers wrote in the report.

USDA scientists at the U.S. Meat Animal Research Center in Clay Center, NE, are currently studying the possible link between feeding cattle up to 40% DDGs and the prevalence of E. coli. The results are expected later this year.

USDA is unlikely to halt the use of DDGs in feed, even if further research confirms a connection with E. coli in cattle. According to a Des Moines Register story, Richard Raymond, USDA undersecretary for food safety, said it will be up to the industry to decide how to deal with the problem.

Clint Peck is director, Beef Quality Assurance, Montana State University.

Key points:

  • The “energy credit” attributed to ethanol byproducts creates a positive energy balance for ethanol production.

  • Dried distillers grains production is expected to level off at over 40 million tons annually by 2018.

  • Distillers grains (DGs) are an excellent source of undegraded protein for stocker calves, replacement heifers and beef cows.

  • Variation between ethanol facilities and processing conditions can affect the nutrient profile of DGs.

  • Researchers are studying the possible link between feeding DGs and prevalence of E. coli O157:H7.

Other co-products examined

The search for renewable-fuel sources has spurred rapid growth in several biofuels, especially biodiesel and ethanol. Biodiesel in North America is made predominantly from soy and canola oil, with some being manufactured from reclaimed animal fats as well as spent cooking oil.

Feed byproducts from these endeavors include vegetable proteins like soybean meal (whose use is not likely to change) and glycerol. The Food and Drug Administration hasn't yet granted feed approval for crude glycerol from biofuel manufacturing.

Higher prices and alternative industrial uses for this co-product will likely limit glycerol use in beef production, says Lance Forster, Jr., Archer Daniels Midland nutritionist.

The corn wet-milling industry continues to convert some capacity to increased ethanol production. No new co-products are made as these wet mills make ethanol alongside high fructose corn syrup or starch products.

The primary co-product of interest to the beef industry is the continued supply of corn-gluten feed in both wet and dry forms. The use of wet milling co-products in beef rations has been well documented over the last 50 years.

The flexibility of the large wet-milling companies will enable them to keep running at capacity for corn grind while adjusting their product mix to current market conditions.

Roughly 8.5 million tons of corn-gluten feed are produced by U.S. mills; the majority goes to feeding beef cattle. The level of gluten-feed production has remained relatively stable the last 5 years.

Additionally, steepwater (condensed fermented corn extractives) production from these facilities provides a viable feedstuff as well as ration conditioner that's been used extensively throughout the cattle-feeding industry.

Like the corn-gluten feed production, no increase in steepwater production has been seen in the last several years.

Proceedings of the 2008 International Livestock Congress-USA