New approaches to increasing corn silage use in beef cattle finishing diets

For producers with an integrated crop and livestock operation, silage has historically been a good option when corn grain prices were high. Relative to corn grain and dry stover, more nutrients are retained as cell solubles or sugars in the plant.

Matt Luebbe

The benefit from this is a digestible fiber source and also a ruminally digestible concentrate source as high-moisture corn when harvested as silage.

Physical control of the feed and inventory throughout the year can have pros and cons depending on markets during that time period. Even though there are additional storage costs associated with harvesting silage, there are also costs to storing dry grain after harvest.

One goal producers have when harvesting corn silage is to maximize the total digestible nutrients per acre.

Corn hybrids are available specifically for silage, but many producers are choosing a dual-purpose hybrid that allows them to take advantage of the markets and decide if they want to harvest the crop as silage, corn grain alone or corn grain with the residue grazed or baled for feed.

Measuring traditional silage studies

Most data available evaluating silage in beef cattle operations suggests that as silage replaces corn in the diet, average daily gain decreases and feed efficiency gets worse. To improve feed efficiency, most commercial feedlot operations reduce the amount of roughage used in finishing diets to increase the amount of corn grain and improve performance.

While these feedlots may have improved feed efficiency and greater average daily gains compared to those feeding a greater amount of silage, the cost of gain may increase to the point that optimum profitability is not realized in an integrated crop-livestock system.

Many of these integrated crop and livestock operations are located in the Midwest and have access to distillers byproducts. Several experiments conducted at the University of Nebraska were focused on determining the impact of elevated levels of corn silage when wet distillers grains are fed.

In these experiments, corn silage was increased from 15 percent of the diet on a dry matter basis to 30 percent and 45 percent with the silage replacing corn grain.

Wet distillers grains were included at either 20 percent or 40 percent of the diet dry matter that also replaced corn grain. Results from these experiments were similar to the historical data, with cattle being fed higher amounts of silage having lower average daily gains and poorer feed efficiencies.

However, feed efficiencies for cattle fed 45 percent silage with distillers grains were only 8 percent worse compared to the control diet, while the historical data suggests that feed efficiency is 15 percent poorer when 45 percent silage is fed without distillers grains.

The reduction commonly observed in feed efficiency when high levels of silage are fed was cut in half.

Based on these observations, there are synergistic effects when higher levels of silage are fed with distillers grains. A companion digestibility experiment was conducted, and the results show that when corn grain is replaced with silage and distillers grains, ruminal pH and fiber digestibility is increased.

These results help explain why the reduction in performance is not as great as previous data would suggest without distillers. These diets may be more profitable to an integrated production system under both high corn prices or at the current market.

From rumen to manure

For integrated crop/livestock operations, the combination of distillers grains and elevated levels of corn silage help to improve nutrient utilization in the entire system. Producers can take advantage of the entire plant and return a portion of the nutrients when manure is applied back to the fields where silage was chopped.

When higher levels of silage are fed, a greater amount of the nitrogen excreted from the animal is recovered in the manure and not volatilized.

Silage has a lower digestibility compared with corn grain and decreases the amount of ammonium excreted, which is rapidly converted to ammonia, the largest loss of nitrogen from manure. The amount of ammonium is reduced both within the animal and on the pen surface when there is more organic matter or undigested feed.

There are additional pen-cleaning and trucking costs associated with a greater quantity of manure, but the value as a fertilizer source is increased because more nitrogen is available for crop production.

When distillers grains are fed in combination with elevated levels of corn silage, there is a greater amount of both nitrogen and phosphorus in the manure, which adds value as a fertilizer. If manure is applied to a corn/soybean rotation based on phosphorus, the first-year nitrogen availability is much closer to crop requirements.

Good management practices for optimum silage harvest and storage are a critical component to the success of integrated operations that use this type of feeding and crop management system. Corn silage maturity or moisture content, packing density and shrink losses are some of the major factors that influence the amount of nutrients lost between the field and feedbunk.

If the paradigm of maximizing feed efficiency and average daily gain is challenged in these integrated crop and livestock systems, overall profitability may be improved.

Additional information about feeding elevated levels of corn silage and other beef production tips can be found online (UNL Beef).

PHOTO: A companion digestibility experiment was conducted, and the results show that when corn grain is replaced with silage and distillers grains, ruminal pH and fiber digestibility is increased. Photo by Staff.