Chemically treated feed may provide winter alternatives

News
Oct 14, 2013

As ongoing droughts force western cattle off summer range earlier than usual, and with every indication of an early winter on the way, ranchers throughout the west are re-evaluating their winter feeding programs. As costs mount and hay prices rise, many are seeking alternatives to hay and other traditionally costly commodities. According to a few nutritionists, one such alternative may lie in the use of straw, corn stalks or other marginal feeds treated chemically to reduce the effects of lignin.

Lignin is a component of fiber in plant tissue. Along with cellulose and hemicellulose, it maintains the structure of the plant. However, while cellulose and hemicellulose can be digested to some degree by the rumen, lignin cannot. As plants mature, lignin levels increase, leaving crop residues such as straw or corn stalks high in lignin and lacking in digestibility. While the chemical bonds of lignin cannot be completely broken down, researchers at the University of Nebraska at Lincoln (UNL) have shown that the application of specific chemicals can weaken those bonds, allowing rumen bacteria to digest previously inaccessible cellulose and hemicellulose lying beneath.

In a study conducted last year, UNL researchers showed that, by adding calcium oxide to wet corn stalks at a rate of five percent, the total digestible nutrient (TDN), a measure of the feed’s digestibility, could be significantly increased.

“Ordinarily, we would assign a value of about 45 percent TDN to wheat straw or corn stalks,” explains UNL extension feedlot specialist Galen Erickson. “Using treatment, it goes up to 55 or 58 percent.” When included in a feedlot ration, continues Erickson, the material appears to perform even better. “Based on performance, it looks like TDN goes up to 75 percent when you look at it in a feedlot diet,” he explains. “It’s not entirely clear why it seems so much better when you feed it at lower inclusions in a feedlot diet, but that is what the data shows.” Erickson also notes that treating the forage in this manner also appears to increase palatability.

Despite the potential benefits, however, Erickson is quick to point out that treated feeds are not a universal solution. While the calcium oxide itself costs $12-15 per ton to apply, Erickson estimates that the added labor and equipment costs to perform the treatment add roughly $50 per ton to the price of the original feedstuff. “At that price,” says Erickson, “I worry about it being economical to feed cows and growing calves.” In Nebraska, he points out, commodities such as distiller’s grains or corn silage often remain a less costly choice. “I don’t want to lead producers astray,” he says. “I think that it can work well, but when it comes down to it, you’ve got to price feeds on a per unit of TDN basis, and see if treating is going to be an economic benefit.”

In the west, however, where the availability of alternative feeds is lower, and the price higher, these treated materials may be a more attractive option. According to Hermiston, OR, nutritionist Michael Mehren, treated straw or corn stover has substantial potential to replace more costly energy sources in a variety of feeding applications. “It’s literally got the energy of corn silage, though it is very low in protein,” he says. “If you add it to a balanced ration, you’re not really feeding straw anymore, but something with much higher energy.”

Mehren, working as an independent consultant with Pacific Ag in Oregon, has been producing thousands of tons of treated straw and corn stover for local producers for the past three years. The possibilities of the product, he says, are exciting in an area that relies heavily on crop residue for winter cattle forage. “We’ve used it everywhere from finishing cattle to cows, weaned calves, developing bulls and backgrounding. We’ve used it almost any place you can use forage in a beef diet,” he says.

The treatment process is not without its difficulties, however, notes Mehren. “Basically, we’re taking baled straw or corn stover, chopping it, and adding water to it to bring the total moisture level up to 50 percent,” he says. Because of the difficulties of chopping corn stalks with traditional machinery, a wood chipper has been employed to achieve the desired twoinch chop. “It’s very important that you have enough moisture,” he adds. “Moisture drives the reaction.”

Once the correct moisture level is reached, dry calcium oxide powder is added at a rate of 5 percent. “It’s quite important that we get a reactive grade of calcium oxide, and that it is a fine powder form.” says Mehren. All ingredients are combined in a mixer wagon for 10 minutes and dumped on the ground to cure. During the curing process, which takes 2-4 days, Mehren indicates that the material gets very hot, hot enough to burn skin, and the pH becomes extremely alkaline. “The pH gets up around 12,” says Mehren. “Once the reaction is complete, the pH drops back down to nine.” This drop, he says, is the best indicator that the reaction is complete.

Once cured, the resulting material can mold. To avoid this, Mehren indicates that a producer must decide whether to treat the material in small batches, or to generate a supply for the whole winter, and pack it as you would silage.

There are also significant safety concerns related to handling the calcium oxide itself, which can be extremely dangerous. “When you get a little bit of moisture on calcium oxide, things around it will catch fire,” says Mehren. He stresses that the substance must be stored where it will not get wet. “We have actually seen where we haven’t put enough water into the mixing truck and, poof, we had 12 or 15 little fires. You’ve got to have at least 90 percent of the total water in the mix before you add the calcium oxide in,” he says. “You’ve got to pay attention all the time,” he adds. “It will burn your skin and eyes, so we wear goggles, breathing masks, long sleeves and gloves when handling it.”

For Mehren and his customers, however, the benefits appear to outweigh the risks. “We’ve fed cows in the late winter with 40 lbs. per cow of treated straw per day, and 8 lbs. of alfalfa, and maintained condition,” he says. “That’s pretty significant.” He points out that, in a region such as the Pacific Northwest, where residues such as straw are much more available than more traditional feeds, the potential uses are numerous. “It’s been really exciting,” he says. “I’m pretty near the end of my career, and to have something like this come along, and to be able to pioneer doing it in the Northwest, it’s been pretty awesome.” — Jason Campbell, WLJ Correspondent

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