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Wheat DDGS as livestock feed

by Susan Reidy
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A new guide published by the Canadian International Grains Institute (Cigi) offers advice on the use of wheat distillers dried grains with solubles (DDGS) for beef, dairy cattle, swine, poultry and aquaculture.
 
The Wheat DDGS Feed Guide, produced on behalf of the Feed Opportunities from Biofuels Industries (FOBI), is a practical guide so the industry can use the product to its full potential and create opportunities for wheat in industrial applications, said Rex Newkirk, guide editor and Cigi director of research and business development.
 
“As a byproduct of ethanol production, which has grown in importance in Canada, wheat distiller dried grains with solubles is an excellent animal feedstuff,” Newkirk said.
 
Wheat ethanol production in Canada has increased from one facility in Lanigan, Saskatchewan to six sites in Western Canada by 2007. The ethanol industry uses 1.4 million tonnes of wheat per year and creates about 500,000 tonnes of wheat DDGS. Complete utilization of the wheat seed through ethanol and DDGS production is necessary for financial profitability, Cigi said.
 
Production increase
 
In 2010, Canadian ethanol plants produced 1.36 billion liters of fuel derived from 64 percent corn, 31 percent wheat and 1 percent other feedstocks. Wheat DDGS is a byproduct of ethanol production and is a combination of the condensed liquid fraction remaining after the ethanol is extracted and then added back into the coarse ethanol-free solids, Cigi said. Almost all of the wheat DDGS produced is used as a feedstuff, although some uses have been explored in soil fertility trials.
 
Ethanol production from wheat is expected to increase, according to the guide. Canada produces 23.2 million tonnes of wheat per year, with majority exported worldwide. It is a readily available and relatively low-cost feedstock for ethanol production.
 
In the past, corn DDGS was often used as a reference point of wheat DDGS. Now, the FOBI Network has researched the nutrient composition of wheat DDGS and noted the differences between it and corn DDGS.
 
Dry matter crude protein levels, which fall in the range of 8.5 percent to 14 percent in wheat prior to processing, increase to a range of 20 percent to 38 percent after the wheat is processed into DDGS. Similarly, fat levels, which are in the range of 1.6 percent to 2 percent prior to processing, increase to a range of 2.5 percent to 6.7 percent after processing.
 
In comparison, corn’s crude protein ranges from 7.4 percent to 10 percent prior to processing, and increases to a range of 23 percent to 32 percent afterward. Fat increases from a pre-processing range of 3.5 percent to 4.7 percent to a range of 9 percent to 12 percent, following processing.
 
Wheat DDGS is typically higher in protein, 40 percent versus 30 percent, and lower in oil, 5 percent versus 10 percent compared to corn DDGS, Cigi said.
 
Product variations
 
One of the biggest concerns in increasing acceptance and use of wheat DDGS is product inconsistency, Cigi said, an issue that also has plagued corn DDGS. Because it is a byproduct, quality control on the past has occasionally been overlooked. Variations have been seen from plant to plant, and in some cases from batch to batch, Cigi said.
 
Plant-specific processes like fermentation conditions, drying method, the amount of solubles added back in, and the grinding procedure can contribute to product variability. Drying can add significant variability, Cigi said, including particle size and differing moisture contents. How much solubles are added back to the DDGS impacts nutritional values, the binding of feed particles and overall particle size.
 
That variability factor is one of easiest to control, Cigi said. Solubles are high in fat and low in neutral detergent fiber (NDF), so the more added to wheat DDGS, the higher the fat and lower the NDF content.
 
The quality of the wheat feedstock at the front end of the process also impacts the DDGS that come out the end. Soil nutrients and growing conditions vary among regions, which impact the wheat nutrient composition. Starting the ethanol production process with a feedstock of consistent type and origin improves the chances of producing a consistent DDGS, Cigi said.
 
In addition, the blend of the beginning feedstocks also contributes greatly to the final DDGS. Some wheat facilities will blend corn into the feedstock, which is likely the greatest source of variation in the resulting DDGS, Cigi said. The guide provides a table showing the impact of changing the ratio on the DDGS nutrient composition as well as equations that can be used to calculate the DDGS nutrient content based on the proportion of wheat and corn used.
 
Livestock rations
 
Wheat DDGS are an excellent feedstuff to include in ruminant diets, Cigi said. Overall, research has shown the animal’s performance is favorable with dry matter intake, average daily gain-to-feed ratio, days on feed, milk production, milk quality and meat quality equivalent or slightly better than standard diets.
 
Cigi said wheat DDGS can act as an energy and/or protein source at a 15 percent inclusion rate. Unlike corn DDGS, feeding wheat DDGS to ruminants does not cause a decrease in dry matter intake because it doesn’t have the high oil content.
 
However, Cigi noted, careful monitoring of the nutrient concentrations is important. For example, sulfur content can vary widely among DDGS. A high level of sulfur in ruminant diets can cause depression, behavioral changes and neurological disorders.
 
In beef finishing feedlots, the differences between corn DDGS and wheat DDGS are even greater. In one study, when cattle were fed 20 percent to 40 percent wheat DDGS, the resulting carcass quality was consistent with barley-finished cattle. In comparison, the animals fed corn DDGS had more backfat, lower lean yield and less ribeye area.
 
Meat quality (chemical composition, cooking time, cooking loss, tenderness) was similar in steaks from steers fed wheat DDGS to those fed barley.
 
For poultry, wheat DDGS is an effective ingredient, Cigi said, and can be included at a 10 percent to 15 percent rate. The DDGS contains similar amounts of protein and branched chain amino acids as canola meal, and is comparable to soybean meal in crude fiber and total sulfur amino acids.
 
In swine diets, wheat DDGS is cost effective and be included in mash diets from 10 percent to 20 percent, depending on the age of the animal. Samples should be evaluated for digestible or available energy and amino acid content, Cigi said.
 
Unlike corn DDGS, wheat DDGS has a relatively small impact on carcass quality due to the lower fat content. Therefore, it can be used in higher quantities than corn DDGS in finishing diets.
 
Limited information is available on feeding wheat DDGS to aquaculture. One study showed it is feasible to use 10 percent corn DDGS in rainbow trout diets. However, the fish require high levels of protein and fat and have little capacity to digest fiber, which makes corn DDGS only marginally feasible. Wheat DDGS has significantly higher levels of protein but less fat and more fiber than corn DDGS, which also limits its use in salmonid species.
 
However, the fine components from fractionated wheat DDGS contain less detergent fiber, making it more suitable for salmonid diets. Digestibility of the energy and dry matter of the fine fractions were higher than in the starting material and were similar in composition and digestibility to soybean meal, Cigi said.
 
Aqueous extraction of protein from wet wheat DDGS further improved the nutritive value. All the fractionation steps are completed before the drying process, therefore no additional drying costs are incurred. Adding this product at up to 30 percent of the diet did not decrease growth performance of rainbow trout, Cigi said.
 
“Wheat DDGS may be added to salmonid diets at low levels but fractionation prior to feeding offers significant benefits nutritionally and makes it more practical as an aquaculture feed,” the group said.

This article ran in Biofuels Business Quarterly, a sister publication of Meat&Poultry magazine.

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