Fat chance: Research links ethanol byproduct to flabbier pigs

US - Pork producers who expect to bring home the bacon by feeding their herds an ethanol byproduct could wind up producing bacon consumers don't want to bring home.
calendar icon 7 May 2007
clock icon 5 minute read

Replacing large amounts of corn with dry distillers' grains with solubles (DDGS) in swine diets adds excessive unsaturated fatty acids, said Mickey Latour, a Purdue University Extension animal scientist.

Higher than expected levels of unsaturated fatty acids affect the appearance of bacon and sausage, and could affect taste, Latour said. In addition, the balance of Omega-6 to Omega-3 fatty acids in the pork products are likely to be tipped toward unhealthy dietary levels, he said.

"What we've found is that replacing 10 to 12 percent of the corn with DDGS in pig diets is doable," Latour said. "For gilts it may be more in the range of 6 to 8 percent because gilts tend to have softer fat relative to barrows.

"DDGS is a good product for pigs, but you have to be careful how much they are fed," Latour said. "If a producer tries to replace too much corn with DDGS it will significantly lower the quality of certain meat products, especially bacon and/or sausage. That would lead to the products being discounted at the time of sale, if a buyer wants them at all."

DDGS is the grain product left over after ethanol is extracted from corn. The product can be used as livestock feed and has been touted as a potentially inexpensive option for producers who are being priced out of the corn market by ethanol companies. Indiana ethanol plants are projected to produce 1.4 million to 1.9 million tons of DDGS per year when the plants are fully operational by 2009 - more than enough DDGS to meet the feed requirements of the state's livestock.

While beef cattle can consume up to 30 percent DDGS without meat degradation, the same is not true of swine. Research by Latour and fellow Purdue animal scientists Brian Richert and Allan Schinckel finds that the pig's unique body composition turns DDGS into soft fat at rates higher than when the pig is fed a straight corn-soybean diet.

"Our research shows that when you start getting close to 20 percent DDGS you're going to have fatty quality issues," Latour said. "So I think it's impossible for producers to try to feed 20 to 30 percent DDGS and think they'll be OK."

Bacon produced from pigs fed little or no DDGS is very firm, ideal for slicing, and creates well-defined lean and fat lines. Bacon from pigs fed high levels of DDGS is flabby - commonly shown as "bending" - and exhibits smeared-looking fat and lean lines. Non-DDGS sausage has a richer color and texture, while pigs fed large quantities of DDGS produce sausage that appears pale and undesirable.

DDGS also affects the nutritional value of pork products, Latour said. As the percentage of DDGS fed to a pig goes up, so, too, does the ratio of Omega-6 to Omega-3 fatty acids. Although Omega-6, or n-6, fatty acids are a necessary part of the human diet, excessive levels are believed to increase the risk of cardiovascular diseases. Omega-3, or n-3, fatty acids are known to be healthy fatty acids.

"Dieticians would recommend we consume foods with a n-6 to n-3 ratio of between 4-to-1 and 6-to-1," Latour said. "Sausage, in general, has a n-6 to n-3 ratio of about 25-to-1.

"Our research indicates that if you add DDGS to a pig's diet the n-6 to n-3 ratio could go above 36-to-1. The reason is that the primary component of DDGS is linoleic acid, or corn oil. You're just pouring it on. It's very likely that the n-6 to n-3 ratio could even be as high as 70- or 80-to-1."

Latour said few pork producers are feeding DDGS, and availability is one reason.

"Also, the DDGS coming out of ethanol plants right now tends to be inconsistent in terms of how it is dried," he said. "You could end up with a product that's a nice gold color or end up with a product that looks like coffee beans. You could feed it, but you'd get nothing out of it.

"Another reason not many pork producers are feeding DDGS is that the industry hasn't figured out a good way of processing it for bulk use. And, on top of all that, DDGS doesn't have a price advantage right now. In fact, the last time I checked, it actually costs a little bit more than corn."

The market for DDGS is likely to shift in the coming years, however.

"Once all these ethanol plants come on line, that dynamic will change fast," Latour said. "And if DDGS becomes abundant and corn prices are higher, as predicted, we'll probably see some producers push the envelope on how much DDGS they add to their herd's diet.

"Hopefully, by that time they'll at least understand there could be consequences."

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