Back in the day, corn kernels used to be soft so they would be easily digestible for the livestock who ate the grain. But as decades passed and the market for exported corn grew, those softer kernels began to disappear, replaced by harder corn that would stand up to the rigors of handling and transportation.
For livestock producers — especially dairy producers — starch availability is once again a hot item of discussion and there is once again interest in so-called "floury" corn.
Mark Kirk, marketing manager for Masters Choice, an independent corn breeding and marketing company based in Anna, IL, said the company wants to be known for floury grain. He spoke at a seminar in Arlington Tuesday (Jan, 14.)
High sugars and floury texture of the grain are physical characteristics that help it be more easily digestible to cows.
The matrix that holds the starch together in the kernel, called prolamin, is also reduced in certain hybrids, which makes the starch molecules break off and again be more useful to the livestock that eat it.
He used Illinois Crop Improvement testing to compare the company's floury hybrids to industry averages. Most elevators will pay "endo" premiums, he said, for harder corn because it handles better.
While his company has some hybrids that tested right alongside these industry averages, most of them came out softer, which is what they are aiming for.
Most of their hybrids fell into the floury, semi-floury or medium ranges for softness. Further grinding tests confirmed that these corn kernels are softer, though Kirk notes there is no industry standard for "floury" grain.
Research at Michigan State University, using cows with rumen cannulas (openings that allow feed samples to be taken from living cows) showed that these kinds of corn stay in the rumen longer.
The research showed that floury endosperm corn, when ground and fed in the cows' ration, stayed in the rumen about the same rate as high-moisture conventional corn, which is traditionally considered to be the best type of corn for dairy cows.
Hard endosperm corn that was ground and added to the ration passed through the rumen at about twice the rate of the floury endosperm dry corn in these trials, he said.
When this floury endosperm corn is used in a ration as high-moisture corn, Kirk said 96 percent of it is still in the rumen after an hour.
Conventional corn kernels, called vitreous for their glassy texture, don't stick to the mat of forage in the cow's rumen as well, he said, which means they can often sink to the bottom of the rumen and pass through the digestive tract.
The softer, more floury kernels stick to this rumen mat and hang around longer, allowing the cow's digestive processes to get more out of them.
Kirk told farmers and nutritionists at the seed meeting that this combination of softer grain and slower rate of passage through the rumen increases the yield of microbial protein in the cow and makes the forages work better in the ration too.
In addition, he said the softer nature of these corn starches means that they are more readily available sooner after harvest. With some of the harder endosperm corn varieties, farmers may have to wait up to 10 months for the starch to be available.
But these floury hybrids make 75 percent of their starch available in less than two months of silo storage, he said.
Kirk said these hybrids aren't associated with any yield drag and have been tested in plots in New York, Idaho, Illinois, Indiana and Wisconsin.
There has only been one trial on one farm in one year to compare the floury corn hybrids to brown mid-rib (BMR) corn — another type of hybrid that dairy farmers have a specific interest in.
In that New Hampshire trial, the Masters Choice hybrid outyielded the BMR by four tons per acre, he said. The fiber digestibility of the two corn silages was about the same, he said, but the starch digestibility was very different.
Fiber digestibility is what the BMR corn varieties are generally known for.
Corn silage derived from these floury hybrids has come out very well in the World Forage Super Bowl contest at World Dairy Expo, he said, garnering 16 top 10 placings.
When tested for total tract digestibility, using the system developed by Dr. Dave Combs at the University of Wisconsin, they came out the highest among the top ten samples, he added.
Kirk, who also works as a Baptist minister, grew up central Texas and has a degree in agriculture with a specialization in production.