We have gone from 1 billion bushels of corn being used for ethanol in 2002 to 9 billion bushels in 2011.
As the ethanol industry’s steady expansion persists and corn prices continue to climb, it has become commonplace for many cattle producers to turn to the renewable fuel’s byproduct for a feed source.
Used as an energy source, distillers grains can be a reasonable, cost-effective corn replacement. On average, the price of dried distillers grains (DDGS) is about 85 percent of the price of corn. This price can vary seasonally but still continues to be a good option for livestock feed.
Currently the beef industry uses 41 percent of all DDGS, followed by the dairy industry at 26 percent; 22 percent are exported, 5 percent are used in the pork industry and 4 percent in the poultry industry.
Besides cost effectiveness, feeding distillers grains to ruminants has other benefits. The feed source can also be an excellent source of protein, energy and minerals.
With distillers grains, the phosphorus requirement can be met quickly, allowing nutritionists to remove inorganic and other sources of phosphorus from the diet.
All DDGS are not created equally
However, distillers grains do come with some disadvantages, too. Byproducts and coproducts may be easier to come by but may not be as nutritionally consistent.
The equipment and processing procedures used by individual ethanol plants can affect the nutrient composition and nutrient availability of the DDGS produced.
Grain source and quality can also impact the nutrient profile. Hue can vary, too, but may not necessarily indicate less nutrient quality.
Some DDGS may have dark coloring from overheating during the drying process, which could result in the reduction of availability of certain amino acids.
In areas where DDGS are used for cattle feed, the thin stillage (liquid remaining after fermentation and distillation) that was separated from the grain may be added back on. This also will cause a dark color but will not negatively affect nutrients.
Besides variability, another concern is intestinal digestibility. High drying temperatures can result in indigestible protein levels of 13 percent or more.
Researchers at South Dakota State University compared the rumen and intestinal digestibility of five sources of DDGS. Rumen-undegradable protein ranged from 63.5 to 78 percent.
Intestinal digestibility ranged from 62.5 to 77.4 percent. Lysine was also found to be particularly sensitive to reductions in digestibility due to processing.
Contamination can still happen
Another issue with distillers grains is molds and mycotoxins. During ethanol production, yeast will utilize the highly digestible starch materials to produce ethanol.
After the starch is used, production is left with primarily protein and fiber, the main components of DDGS, to provide an excellent feedstuffs source for animals.
The complication is that any component not used for ethanol will also be concentrated just like the fiber and the protein, and that would include mycotoxins. In fact, mycotoxins concentrate up to three times more in DDGs than in grains.
In the industry, there has been a general misconception that cattle are resistant to mycotoxins. However, research over the last decade has shown that cattle are susceptible to various mycotoxins such as aflatoxins, T-2 toxin, deoxynivalenol, zearalenone and several Penicillium mycotoxins.
Mycotoxins can have acute, as well as chronic, effects on cattle. Good examples of acute effects include the possible role of T-2 toxin in hemorrhagic bowel syndrome (HBS) as well as exposure to ergot alkaloids from tall fescue and ryegrass.
Though the mortality rate is very high in acute mycotoxin cases, this seldom happens in the field. Chronic effects of mycotoxins, due to long-term ingestion at low levels, are a more common situation. Reduced weight gain in beef cattle is one example of a chronic effect.
Take control before toxins get out of control
Field mycotoxins are produced before harvesting and there is not much the animal producer can do to prevent their entry into feeds. The production of storage mycotoxins, however, can be minimized by adopting good storage practices.
The use of a mold inhibitor for high-moisture materials has also been utilized widely to control storage mycotoxins. A mold inhibitor can be applied to lower the pH so that molds will not grow and produce more toxins.
However, an inhibitor is usually only useful to keep the situation from getting worse by killing mold spores and, typically, only if the material is unstable with high moisture.
During his 30-plus years of mycotoxin research at the University of Guelph, Dr. Trevor Smith has worked on finding a number of solutions to the exceeding problems of toxins in animal feed.
The first step he recommends is a quality control program to monitor the toxic content of DDGS and to make sure that the incoming supply of DDGS has manageable levels of contamination.
“We know mycotoxins are going to be more prevalent in certain processed raw materials and also that mycotoxins can negatively affect health and feed efficiency, so it is more important than ever to have a documented mycotoxin control program in place as the price of feed rises, the use of alternative raw ingredients increases and the need for improved feed efficiency is paramount,” said Smith.
The bottom line for producers and nutritionists is that the animal remains the best indicator of a mycotoxin presence. Therefore, if the animal is not performing to its fullest or unexplained symptoms persist, consider the nutrient quality of the DDGS and the role a mycotoxin may be playing.
A final comment by Dr. Jean Pierre Jouany in his 2007 review suggested that the use of an organic mycotoxin sequestering agent with proven efficacy is one way in which producers and nutritionists can help negate the impacts of mycotoxins within the animal, given that so many of the other factors that affect this are out of their control.
References omitted due to space but are available upon request. Click here to email an editor.
Besides cost effectiveness, feeding distiller grains to ruminants can also be an excellent source of protein, energy and minerals. Photo by Progressive Cattleman staff.
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