Does Corn Silage Fed to Feedlot Cattle need to be Kernel Processed?

Sep 06, 2021

By Jerad Jaborek

It’s that time of year again when corn across the Midwest is beginning to reach the ideal maturity needed to produce corn silage. Many producers often question how they can produce the highest yielding or quality crop. A review by Johnson and others in the Journal of Dairy Science report that mechanically processing your corn silage may be an option to improve the quality or feeding value of your corn silage crop. More information regarding corn silage can be found on the Michigan State University Extension corn website.

Fully active mechanical processors are most common and consist of two counter rotating rollers located between the cutterhead and the blower of the harvester. The grooved or serrated rollers crush or shear the corn silage as it passes between the two rollers with a space typically ranging from 1 to 5 mm. However, additional energy (7 to 15%) is required and there is a reduced harvest capacity by the harvester (0 to 28%) when mechanically processing corn silage. The use of recutter screens can also be used but are less common because they produce corn silage with a much finer particle size. Another option for mechanically processing corn silage is with the use of a stationary roller mill which can allow for mechanical processing of corn silage to occur before or after ensiling.

Silage Characteristics

Kernel processors for corn silage are used to cause damage to the corn kernel for improved starch utilization by the animal. Processing corn silage decreases the number of undamaged whole corn kernels. However, corn silage particle size is reduced 15 to 30% as a result of kernel processing. Therefore, when processing corn silage, the recommended theoretical length of cut (TLC) is typically greater than for unprocessed corn silage. The desired TLC will depend heavily on your diet composition. Corn silage is the most commonly used roughage source in Midwest feedlot rations, providing a source of fiber to help prevent digestive disorders such as acidosis.

The chemical compositional differences of processed and unprocessed corn silage are less evident. The finer particle size of processed corn silage may pack more tightly, resulting in improved fermentation of readily fermentable substrates. This causes a lesser pH, greater lactic acid production, and slightly greater fiber (neutral detergent fiber [NDF], acid detergent fiber, lignin) percentage compared with conventional corn silage after ensiling. However, these differences are small and may be more heavily influenced by other factors such as hybrid variety, maturity stage, and TLC than mechanical processing.

In a different Journal of Dairy Science article by Johnson and others, researchers demonstrated that corn plant growth can vary by the year, mainly due to precipitation and temperature differences. In the study, rumen digestibility of corn silage was affected by hybrid variety (high vs. low NDF), corn plant maturity at harvest (ranging from hard dough to black layer), use of mechanical processing (kernel processed vs. unprocessed), and the TLC (ranging from 0.375 to 1.5 inches).

The use of a kernel processor while harvesting silage influenced dry matter (DM), starch, NDF, and crude protein digestibility within the rumen. Dry matter digestibility of mechanically processed corn silage is greater than unprocessed corn silage because of the increased digestibility of starch, particularly in corn silage harvested at a later maturity and for low NDF corn silage varieties as well.

The reason to mechanically process corn silage is because of the greater starch digestibility due to the increased damage caused to the corn kernel. Damage to the tough exterior (pericarp) of the corn kernel allows the rumen microbes access to the starch inside the corn kernel resulting in a greater total tract starch digestibility by the animal. Processing corn silage demonstrated less of an improvement for NDF digestibility. However, when harvested at a later maturity, processing corn silage improved NDF digestibility compared with unprocessed corn silage. Fiber (NDF) digestibility of corn silage produced during hot and dry years as compared with cool and wet years was greater with processing. Similar to NDF digestibility, crude protein digestibility demonstrated little improvement from processing, except for mature corn or corn silage with a shorter TLC.

A Professional Animal Scientist paper, by Ferraretto and Shaver from Wisconsin compiled the results from multiple studies and summarized corn silage harvesting practices effects on digestion and milk production in dairy cows. Kernel processing resulted in 8% whole corn kernels compared with 19% whole corn kernels in unprocessed corn silage. Kernel processing resulted in a greater organic matter digestibility with rollers set either 1 to 3 mm or 4 to 8 mm apart compared with unprocessed corn silage. Total tract starch digestibility was greater for corn silage that was kernel processed at 1 to 3 mm compared with 4 to 8 mm and unprocessed corn silage. Kernel processing effect on total tract starch digestibility is also influenced by TLC and DM content, where DM content may be an indicator of corn plant maturity at harvest. Total tract starch digestibility was greater for kernel processed corn silage compared with unprocessed corn silage when the DM content was between 32 to 40%, and the TLC was between 0.375 to 1.125 inches.

Feeding Performance

While the effect of feeding feedlot steers processed versus unprocessed corn silage has not been extensively researched, the few studies investigating this topic are shared below. In one study conducted by Ovinge and others, published in a Nebraska Beef Cattle Report, feeding processed corn silage at 40% of the diet DM, resulted in a lesser DM intake (0.8 pounds per day) and similar average daily gain (4.4 pounds per day) for yearling crossbred steers. This tended to improve feed efficiency 2.8% for cattle offered corn silage that was kernel processed. Therefore, processed corn silage offered a greater amount of available energy to be used for body weight gain. No differences were observed for carcass traits or diet digestibility due to kernel processing corn silage at harvest. Corn silage used in this study was harvested at a three-quarter milkline maturity, with a 0.75-inch TLC, and 2 mm kernel processing.

Conroy and others, published in a Nebraska Beef Cattle Report, processed corn silage with different TLC (0.51 vs. 1.04 inches) and 1 mm kernel processing was compared and offered at either 9 or 14% of the diet DM to yearling crossbred steers. Offering processed corn silage with a greater TLC resulted in greater and more efficient body weight gains for cattle due to the associative effects of the longer particle length of the corn silage in combination with a high steam flaked grain diet. No differences were observed for carcass traits due to kernel processing corn silage at harvest.

A study published in Journal of Animal Science by Rojas-Bourrillon and others from Iowa reportedly failed to observe a performance and digestibility difference between processed (harvested at black layer maturity, 0.375 inch TLC, and with 0.3 mm kernel processing) and unprocessed corn silage. The lack of differences between the processed and unprocessed corn silage may have been due to an 8.2% lesser ruminal retention time for solid feed particles from processed corn silage to be digested compared with unprocessed corn silage.

A conference proceeding presented at Cattlemen’s Day by Young and others from Kansas State University compared feeding mechanically processed (pre- or post-ensiled) with conventional unprocessed corn silage to crossbred steers and heifers in a backgrounding diet consisting of 90% corn silage. Corn silage was harvested in the black layer stage (mature) and chopped at a 0.375-inch TLC. Offering calves processed (pre- or post-ensiling) corn silage for 80 days resulted in a greater ADG, and a more desirable feed efficiency (+7.1%) compared with unprocessed corn silage. Numerically, DM and NDF digestibility was improved by processing, while corn silage processed after ensiling had the greatest starch digestibility when fed to cattle.

Final Thoughts

When kernel processing adequately damages the corn kernels in corn silage, starch digestibility is improved. Very few studies have investigated the effects of kernel processed corn silage on feedlot cattle performance. In general, results of feedlot performance differences between processed and unprocessed corn silage have been very small or non-existent. Likewise, for dairy cows where kernel processing is more popular, a review on the effects of corn silage processing demonstrated no improvement in milk production. If you have already purchased a kernel processor for silage harvester, go ahead and use it. To conclude, it appears very difficult to justify the added expense of purchasing a kernel processor for the little gain in feedlot performance.

Source : msu.edu

Video: Turning Plant Defense Into a Management Strategy

Turning Plant Defense Into a Management Strategy

Understanding how a plant responds to stress is one thing.

Using that knowledge to make better management decisions is another.

Systemic acquired resistance, or SAR, is the plant's more direct defense response. When stress or infection occurs, the plant begins signaling throughout its system and preparing defensive compounds.

But if we know that response exists, can we help prepare the plant before the stress arrives?

The answer starts with understanding what triggers the response and what the plant needs to carry it out.

The Trigger and the Fuel

Salicylic acid plays an important role in triggering the SAR pathway.

Think of it as turning the truck on.

The engine may be running, but it still needs fuel to do the work.

In this case, manganese plays an important role in supporting the enzyme systems involved in the plant's defensive response.

This makes manganese status an important part of the conversation. Whether a producer is using tissue testing, sap analysis, or simply scouting for visible deficiency symptoms, the goal is to make sure the plant has adequate manganese available.

Manganese is required in relatively small amounts, but that does not make its role small.

If the plant receives a signal to defend itself but lacks the nutrition needed to support that response, it may struggle to carry out the process efficiently.

The trigger matters.

The fuel matters too.

Prepare Before the Stress Arrives

The best time to think about stress management is before the plant is overwhelmed.

Once a crop is already struggling, management can quickly turn into a game of catch-up.

This is similar to nitrogen management. Once a plant becomes severely deficient, correcting the problem does not necessarily erase the time and yield potential already lost.

Plant defense can work the same way.

Low-rate, targeted approaches designed to support the SAR pathway may fit best ahead of an expected stress event rather than after significant damage has already occurred.

That requires producers to think about predictable stress.

We may not know exactly what the weather will do tomorrow, but we generally know summer heat is coming. We know certain field conditions increase disease pressure. We know a herbicide application can temporarily stress a crop as the plant processes the chemistry.

Even a properly timed and labeled herbicide application can create a temporary response in the plant.

That does not mean the herbicide is bad.

Weeds can create significantly more yield loss than the temporary stress caused by controlling them.

The question is not whether we should eliminate every stressor.

The question is whether we can better prepare the plant to manage necessary and predictable stress.

Not All Stress Is Bad

Stress is a normal part of plant growth.

A perfectly stress-free environment does not exist in the field.

In fact, some stress is necessary for normal plant development. A plant responds to wind, temperature, moisture, sunlight, and countless other environmental signals throughout the season.

The environment is stress.

The plant's job is to manage it.

Problems begin when the stress load becomes greater than the plant's ability to respond.

Extreme heat, drought, high salt concentrations, disease pressure, and even certain management practices can add to that load.

This is where understanding SAR becomes useful.

Instead of waiting until the plant is visibly struggling, producers can begin identifying periods when stress is likely and make management decisions around those windows.

ISR Starts With the Soil

While SAR is a more direct defense response, induced systemic resistance, or ISR, brings the conversation back to soil health.

The longevity of a farm is closely connected to the health of its soil.

Carbon plays a major role because it supports biological life within the soil. Bacteria, fungi, and other organisms interact with plant roots and influence how the plant grows, accesses nutrients, and prepares for stress.

This is why soil health cannot be reduced to one product or one application.

It is a system.

Keeping living plants in the field longer can support biological activity. Cover crops may fit some operations. Better water management can improve soil conditions.