30 October 2012

5 minute read

One consideration for livestock producers may be the age-old process of feeding ammoniated low-quality hays or crop residues. Ammoniation can double or triple crude protein levels in crop residues such as straw and corn stalks and increase digestibility 10 to 30 percent, making them equivalent to prairie hay in feed value.

Ammoniation is fairly simple to do, but keep in mind these important considerations. Before you can ammoniate forages, they need to have ample moisture. That may be more of a challenge with many of this year’s forages, which reportedly have less than 10 percent moisture. The lack of moisture is attributable to the dry growing conditions and lower-than-usual humidity.

A low moisture content is great for putting up hay, but it likewise has left much of the hay drier than desirable for this process. Water is the key here. You will have to add water to tie up the nitrogen and keep from losing your expensive ammonia.

That brings up point No. 2: Ammonia fertilizer is not cheap. So if you proceed with ammoniation, you will want to do it correctly. That includes covering the stacks and applying only what you need.

Furthermore, as we move into cooler temperatures, the ammoniation process takes longer. Below 59 F, the minimum time to seal a stack is four to eight weeks. Lastly, working with anhydrous ammonia involves a safety factor that cannot be taken lightly. It is dangerous stuff, so be careful, and have the appropriate equipment on hand and use it.

Another alternative for salvaging harvest residue and fortifying low-quality forage for livestock feed is adding hydrated lime. Hydrated lime is quicklime (calcium oxide) with water added to make it calcium hydroxide. Calcium hydroxide is used in a variety of food applications, from pickling and preserving fruits and vegetables to adding calcium to fruit juices and baby formulas.

The first research on using hydrated lime was conducted on corn stover. Corn stover, in its most basic form, is made up of lignin, cellulose and hemi-cellulose. These elements are not particularly digestible. But new research has shown that a substantial portion of the grain in cattle feed can be replaced effectively with corn stover - the plant’s stalks, cobs and leaves - when these harvest residues are treated with hydrated lime.

This feeding strategy has been validated through recent studies conducted at Iowa State University and the University of Nebraska.

After shelling the corn, windrow the stalks, add hydrated lime, chop the stalks and store the feed in an oxygen-free container, which typically is a plastic “ag bag” or a bunker, for at least a week.

A 1,200-pound stover bale can be treated with approximately 50 pounds of calcium hydroxide. The solution loosens the chemical bonds between the stover’s less-digestible lignins and its more digestible components. Relaxing these bonds allows natural enzymes to digest the stover.

While research on hydrated lime was done with corn, the same treatment process should make wheat and late-harvested Conservation Reserve Program hays more digestible to ruminants as well. However, application equipment is not readily available.

Hydrated lime is similar to quick lime but releases only a fraction of the heat, so you are not likely to start a fire.

Limited reports note that once the stover is collected and baled, you need to check the moisture content and then grind it in a tub grinder, preferably one with a 3-inch screen. After it is ground, put the stover into a feed wagon with a scale, add a 5 percent treatment of calcium oxide and bring up the moisture content to 50 percent.

For example, for 1,000 pounds of dry stover, a 5 percent treatment would require 50 pounds of calcium oxide. If the bale started with 20 percent moisture content, the bale would weigh 1,250 pounds (1,000 pounds of dry stover, 250 pounds of moisture and 50 pounds of calcium oxide).

The next step is to add enough water to bring the mixture to 50 percent moisture content. In this case, you would add 800 pounds of water. So in the end, you would have 1,050 pounds of dry matter and 1,050 pounds of moisture. It’s a 50/50 mixture, very similar to corn silage.

Another important aspect to the treatment is the pH. The pH of the stover before treatment is usually in the 6.5 to 8.5 range. After the calcium oxide is added, the pH is raised to 12.5. Check the pH in several areas of the mixture to ensure the calcium oxide is mixed in evenly.

After that, dump the mixture onto the ground or in a bunk. Within five minutes, you should see a dramatic change in color; it will turn green. This indicates the lignin, cellulose and hemi-cellulose have begun to break down. This mixture must sit for five to seven days for the chemical reaction to continue. After that, it can be fed to cattle.

You also can process large amounts of the stover and store it in a feed bunker. It will last as long as it is kept away from air, such as under a tarp.

Some producers just run the baler through the field, which leaves about half the material intact and is very hard on the baler. If you have a round baler and are accustomed to baling hay, remember to move the diameter down about 2 to 3 inches when baling corn stalks. Operators say that when the horn goes off, you need to stop immediately or you’ll shear pins.

Producers also have found that abrasion from dirt and grit can be hard on belts and pick-ups. However, when compared with $6- to 8-a-bushel corn, this becomes a very economical option. Researchers reported this corn stover treatment costs roughly $20 a ton.