Boosting marginal feeds
The palatability and nutrient quality of corn stover can be improved by baling, grinding and treating it, reports Mike Mehren, a Hermiston, OR, nutritionist.
“Grinding is the challenge on a ranch, because the stover must be ground fine enough for cattle to eat all of it,” he says. “We use a wood chipper, because tub grinders and hay choppers don’t have the power to handle baled cornstalks,” he says.
The ground stover then goes into a mix truck, and water is added to attain 50% moisture.
“We put just 85-90% of the needed water into the mix truck with the dry ground stover, then mix it thoroughly before adding calcium oxide to comprise 5% of the dry matter. Calcium oxide is used in pickling and costs about $400/ton. It takes about $12 worth of calcium oxide to treat a big batch of straw or corn stover,” Mehren says.
Once the calcium oxide, which breaks down lignin, is mixed in, the rest of the necessary water is added, followed by 10-15 minutes of additional mixing for uniformity. The thick mixture is then dumped onto a cement slab and cured for two to four days, during which the mix heats and pH rises to 12. Once it’s cured, the pH drops to 8 or 9 and some of the heat dissipates, Mehren says. At this point it can be fed.
“We mix the treated roughage with a little hay in a feed truck, and spread it in a windrow on the ground or in a hay feeder,” he adds.
If a rancher is mixing enough to last the winter, he recommends storing it like silage. Properly packed, the product won’t mold, and mycotoxin development is unlikely due to the neutral to slightly alkaline profile.
There are a few cautions when using calcium oxide, however. “When mixed with a little water, or if the bags of calcium oxide get damp, they’ll catch fire. If you put it on dry corn stover, it will catch fire. So you want a lot of moisture. When we work with calcium oxide, we wear long-sleeve gloves, goggles and dust masks,” Mehren says.
Mehren’s firm provides this feed for many clients. “We can do the same thing with wheat straw, which can be done on the ranch. It’s the same process, except that straw bales can be ground in a tub grinder and put into the mix truck, adding the appropriate amount of water and calcium oxide. It comes out a beautiful golden color,” he says.
While he’s only treated grass straw and wheat straw, Mehren believes any straw is a candidate. The bottom line is that the process creates higher-quality forage that reduces the supplement needed to balance the cattle diet.
“I’ve fed cows late in the winter — just starting to calve or with calves at side — 40 lbs./cow of treated straw (50% moisture) and 8 lbs. of alfalfa. This provides a complete diet that holds body condition,” Mehren says.
He’s also used treated corn stover in backgrounding rations for 2.5-3 lbs./day gain. “We use it at about 25% of the ration’s dry matter. I also use it in bull-developing rations at the same level. And we’ve used it in back-to-grass rations where we simply want 1-1.5 lbs./day gain, using the corn stover in higher levels. In every case, we’ve been very happy with the results,” he says.
The University of Nebraska conducted some of the original trials, with treated cornstalks and straw. They were then used as a partial replacement for corn in finishing rations, with satisfactory results in feed conversion, gain, cost of gain, carcass merit, etc., Mehren says.
“This was one of the big steps in converting low-quality byproducts into something that could be part of a high-quality finishing ration. In the future, we’ll see a lot more innovation applied to different feedstuffs,” he concludes.