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Research sees nutritional benefits, increased gains from steam-flaked corn for cattle feed

by Wyoming Livestock Roundup

Assessing the value of a feed resources takes into account many factors, including the uniformity and predictability of the feed, energy value, integration with other dietary ingredients, acceptability of the feed and cost.

Richard Zinn, a professor and researcher at the University of California Davis Department of Animal Science, used these characteristics to assess the value of steam-flaked grain as compared to dry-processed corn.

“When we look at numerous studies conducted with steam-flaked corn, we see average daily gain increasing about six percent when cattle are fed steam-flaked corn,” Zinn says. “We also see a reduction – in this case, about a three percent reduction – in dry matter intake associated with this increase in net energy value.”

Steam-flaking  corn increases starch digestibility, Zinn continues, which is responsible for its superiority as a feed source.


“Often, we focus our attention in assessing feeds on changes in rumen digestion,” he explains. “However, the real problem for ruminants is small intestinal digestion.”

Chyme, which is the digestate in the small intestine of ruminants, is only present in the small intestine about three hours, which is a very short time, Zinn says, noting, “Only about the first half of the small intestine is going to be effective in terms of digestion of starch.”

He noted starch digestion in the small intestine may be anywhere from 50 to 95 percent complete, which is a big range.

“When we look at dry-processed grain compared to steam-flaked grain, we can see that, on average, starch digestion in the small intestine increases from 63 percent for dry-processed grain to about 94 percent for steam-flaked grain. This is about a 49 percent increase in the availability of starch in the small intestine.”


Steam-flaking corn involves disrupting starch granules surrounding the hard endosperm, which is called the horny endosperm of the corn, allowing it to be more easily digested.

“The horny endosperm is encapsulated in a protein matrix of starch granules,” Zinn explains. “It is very difficult for enzymes to digest this endosperm, particularly in the small intestine, so it probably won’t be digested at all normally.”

He adds, “When we flake corn, we’re attacking the horny endosperm and that protein matrix to make the corn more digestible.”

Disruption of the protein matrix in the endosperm is the result of two processes – moisture uptake and mechanical flaking.

“We disrupt the protein matrix through the swelling of the granule itself that’s accomplished during the cooking process as moisture is increased, and then, we further disrupt the matrix as the grain passes through rollers,” Zinn says.

Flake quality

To discern what is important in assessing quality of steam-flaked corn, Zinn notes his team studied day-old, steam-flaked corn that had been air dried compared to fresh-flaked grain.

“In terms of digestion, we can see no difference due to the small amount of retro-degradation that happens as the grain dries,” he says. “The quality of steam-flaked corn is affected by how well the grain was actually flaked. We look at flake thickness, flake density, enzymatic reactivity and fecal starch.”

The thickness of a flake can be measured in a precise, scientific manner, taking 10 whole flakes and literally measuring their thickness. Optimal flakes are usually 1.6 to 1.8 millimeters thick.

“More commonly, we measure bushel weight, which looks at density,” Zinn says. “Bushel weight can be measured rapidly, and it gives us consistent results.”

Flaked corn typically weighs 24 to 28 pounds per bushel.

“However, we have to remember the object of flaking is optimal starch utilization,” he emphasizes. “The most reliable indicator of quality is fecal starch.”

Assessing the fecal starch from cattle fed flaked corn can help operations determine whether the flaked corn is thin enough to achieve optimal starch utilization by the rumen.

Seeing results

From extensive research, Zinn quantified the benefits seen from steam flaking corn fed to cattle.

“When we substitute steam-flaked corn for dry-processed corn, we predictably increase average daily gain by about six percent,” he said. “Steam flaking increases the net energy for maintenance value by 13 percent and the net energy for gain value by 15 percent.”

Zinn continues, “Steam flaking increases total digestion by about 10 percent, and that corresponds almost perfectly with the 13 and 16 percent improvement in performance.”

Additionally, when grain is flaked properly, less than three percent starch is found in fecal samples, which means cattle are utilizing the grain more efficiently.

Zinn comments, “It’s a big mistake to not be flaking the grain.”

Saige Albert is managing editor of the Wyoming Livestock Roundup. Send comments on this article to

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