High moisture corn is, as the name implies, corn harvested before the kernels dry down, usually processed by a roller mill or hammer mill, packed into an appropriate structure and allowed to ferment. High moisture ear corn is similar to high moisture corn but it includes some portion of the cob. Snaplage includes the grain, cob, and shuck (husk leaves and shank).

Many producers use harvest options that reduce cost or spread the harvest window. For livestock producers, harvesting corn as high-moisture grain is one option that will eliminate grain drying costs and produce a product that makes excellent feed for ruminant animals.

High-moisture corn (HMC), high moisture ear corn (HMEC) and snaplage offer many advantages for producers who feed beef or dairy cattle. However, successfully using high-moisture corn requires attention to harvest timing, processing, storage conditions and feeding management.

What is High-Moisture Corn?

High-moisture corn refers to corn harvested at 24 percent or greater moisture, stored and allowed to ferment in a silo or other storage structure, and used as feed for livestock.

Estimating the Value of Wet Ear Corn--A Suggested Starting Point UWEX Bulletin A3410
Usually harvested at 28-32% kernel moisture
Equivalent Price/Ton of High Moisture Ear or Shelled Corn vs Price per Dry Bushel: conversion tables for converting wet ear corn and wet shelled corn to its dry corn price equivalent. Developed by Jeff Key, Winnebago County and Gary Frank, Center for Dairy Profitability

Advantages of High-Moisture Corn over dry grain harvesting

Spreads work load
Reduces harvest losses
HMC is more palatable than dry corn
Elimination of grain drying costs.
Yields typically are increased due to less ear drop in the field.
Longer-season (greater relative maturity) corn can be grown with greater yield potential.
The ability to use an immature crop; Earlier harvest.
High-moisture corn allows 2 to 3 weeks earlier corn harvest than dry grain, between corn silage and dry grain potentially spreading the workload during harvest.
Earlier availability and longer window for cattle grazing corn residue.
The ability to minimize sorting by adding moisture to the diet.

Disadvantages of High-Moisture Corn

Loss of marketing flexibility. High-moisture corn is marketable only through livestock. Since it has fermented, high-moisture corn cannot be marketed for ethanol production or other uses typical for dry corn.
More storage and processing equipment.
Potential higher spoilage and storage losses.
High-moisture corn tends to ferment faster in the rumen and requires better bunk management, compared with dry corn. More likely to be associated with acidosis.

The approximate dry matter composition of HMC, HMEC and Snaplage.

	High Moisture Corn	High Moisture Ear Corn	Snaplage
Corn, %	100	84-94	75-80
Cob, %	0	10-16	10-15
Husk, %	0	0	5-10
Crude protein, %	9.5	9	8.5

Advantages of high moisture ear corn and snaplage over high moisture shelled corn include:

Increased tonnage harvested per acre. Can harvest 15-20% more feed/acre with HMEC than with HMSC
Milk production/lb of feed is slightly better for HMEC
Cows don't go off feed as often with HMEC. Digestible and effective fiber - all the components of high moisture corn, high moisture ear corn and snaplage are highly digestible. Corn cob and husk have the added benefit of containing effective fiber. Effective fiber helps protect the rumen from acidosis. The effective fiber contained in these ingredients reduces the amount of forage that needs to be included in the ration to maintain optimal rumen health.

Disadvantages include:

Mycotoxin concentration in the cob portion. Avoid harvesting moldy or damaged corn as ear corn or snaplage.
The need for increased storage capacity to handle the extra volume coming from the cob and husk.

Harvesting

High-moisture corn should be harvested at 24 to 33 percent moisture for optimum storage (maximum moisture of 40 percent). Harvesting corn at these moisture levels may require adjustments to harvest equipment to ensure grain is removed from the cob uniformly. Some damage to the grain is acceptable because it still will need to be processed prior to ensiling.

Handling and processing of HMC for good packing and fermentation

95% of the kernels should be cracked or broken
Cob pieces shouldn't be larger than 1/2 inch
Grinding too fine will result in floury HMC

Most high moisture corn is processed (rolled or ground) before going into the storage unit. The two exceptions to this rule are shelled corn being stored in an oxygen limiting unit and corn that is excessively wet (near 35% kernel moisture). Take care not to over process corn that is over the desired moisture level. It is easy to get excessively fine high-moisture corn that may result in rumen acidosis, fat test depression, off-feed problems or an increased incidence of displaced abomasums. As the corn approaches optimum moisture content, increase the degree of processing.

High-moisture corn should be processed (ground or rolled) prior to storage. Grinding or rolling and subsequent packing of the corn facilitates oxygen exclusion in the silo. The goal with processing should be to have no more than 5 percent fines and no more than 5 percent whole kernels. For feeding purposes, rolling is the preferred method of processing (compared with grinding) because rolling will result in less fines and lower probability of acidosis due to rapid fermentation when feeding.

While grinding may lead to faster ruminal fermentation and greater risk of acidosis, this problem is an issue only when feeding greater than 50 percent of the grain as HMC in a feedlot diet. With the increased feeding of wet distillers grains, the risk of acidosis from feeding ground high-moisture corn is greatly reduced due to the reduction in total ration starch content. Likewise, most dairies finely grind the high-moisture corn to facilitate greater ruminal digestion, and since grain is generally less than 50 percent of the diet, acidosis is not a problem.

Storage

All high moisture corn feedstuffs must be harvested at an appropriate moisture level and properly ensiled. The corn cob contains higher moisture than the corn grain so high moisture ear corn and snaplage should have higher moisture levels than high moisture corn by itself. Cob digestibility falls off dramatically as the crop matures and moisture levels fall. Moisture testers are available to estimate the moisture of the corn grain. On average snaplage will run about 5% higher moisture content than high moisture corn. Ideally snaplage will be harvested when the corn grain itself tests over 28% moisture.

Ideal moisture levels at harvest

	Minimum	Desired	Maximum
High Moisture Corn - Bunker, Bag %	26	28-32	36
High Moisture Corn - Oxygen Limited Silo , %	24	26-28	32
High Moisture Ear Corn, %	26	32-36	40
Snaplage, %	--	35-38	--

High moisture corn can be stored either whole or ground and in upright or bunker silos. Whole high moisture corn is commonly stored in upright silos. High moisture corn should be ground if it is to be stored in a bunker silo. There is no advantage to grinding high moisture corn beyond the ability to store it in bunker silos. High moisture ear corn needs the cob fraction to be reduced to ½ inch or less to insure adequate packing and consumption by the animals.

At moisture levels below 27 percent, water may need to be added to facilitate packing and fermentation. A good rule of thumb is to add 3.5 gallons of water per ton of corn for each percentage point the corn is below 27 percent moisture.

For corn stored above 40% moisture, an undesirable fermentation may take place and yeast may proliferate along with high ethanol levels. Animal acceptance may be poor with this type of fermentation. Additionally, harvesting high moisture shelled corn above 32% kernel moisture for oxygen limiting silos equipped to handle high moisture shelled corn may result in unloading problems.

Bunker or Trench Silo

This is the best option for large volumes of corn harvested in a short period of time but will require a large-volume roller or hammer mill to process grain rapidly. Packing is done with tractors, which may be equipped with a dozer blade or front-end loaders. The face of the bunker must be kept fresh to avoid heating, so the width of the highmoisture corn bunker should match the rate of use. Multiple narrower bunkers may be more useful than one wide bunker silo. Bunkers constructed of a cement base and sides will reduce spoilage better than earthen structures and provide a firm surface for equipment throughout the year. Proper packing of the high-moisture corn in bunker silos also is critical to oxygen exclusion.

Proper packing, covering and facing will reduce spoilage losses and improve acceptability of the high-moisture corn in the feed bunk. A minimum density of 45 pounds of dry matter per cubic foot is desirable for good-quality high-moisture corn. Packing grain in bunker silos can be dangerous, so be sure an experienced and safe tractor operator is operating the packing equipment. Also, all bunker, trench and pile structures should be covered with plastic to create an anaerobic environment and minimize spoilage. Plastic covers should be inspected periodically and any holes or tears repaired.

Plastic Silage Bags

Bags are filled with a specialized bagger that also will process the corn to reduce oxygen inclusion as it stuffs the bag. Pressure can be varied to accommodate different feed products. Baggers are available for rent or purchase. Bags come in different sizes and lengths. Clear a flat space of rocks and debris, and make sure the space is large enough for equipment to move around to fill bags. Be sure to inspect bags and plastic bunker covers for tears or holes because oxygen penetration in these areas can cause additional spoilage. In addition, producers should monitor bags and bunkers for evidence of wildlife depredation and take necessary steps to reduce depredation and silage losses.

Oxygen-limiting Silos

Whole high-moisture grain may be stored in certain types of oxygen limiting silos. One advantage of these structures is that corn can be stored at lower moisture levels (22 to 26 percent moisture) than in bunker or plastic bag storage structures. Check with the manufacturer to be sure your silo is designed to handle whole high-moisture grain prior to placing grain in the structure.

Additives

Certain additives may be beneficial in reducing fermentation and feedout losses in HMC. Lactic acid bacteria inoculants that have been developed specifically for high-moisture corn should be considered when the corn has been frozen or is harvested below the optimal moisture content. The use of acid preservatives may be warranted if substantial ear mold damage has occurred and mycotoxin production is prevalent in the standing crop. When considering the use of an additive for high-moisture corn, be sure to ask the manufacturer for research data to support efficacy claims.

High moisture corn offers some unique preservation challenges compared to corn silage because it ferments more slowly and less extensively while containing high levels of starch, which promotes aerobic deterioration. Any aid to hasten fermentation, use up available oxygen, and inhibit yeast growth (once exposed to oxygen) is beneficial in the ensiling process. Several options are currently available to producers.

Standard bacterial inoculants

High moisture corn inoculants have been available for many years. These primarily produce lactic acid during the fermentation process (homofermentative) and increase the speed of fermentation, while reducing dry matter loss. They may also increase animal performance. Choose an inoculant that has been specifically developed for ensiling high moisture corn. Specific strains of bacteria may not grow well on all crops and across a wide range of moisture contents. Thus, a corn silage inoculant may or may not work well under the drier conditions of high moisture corn. Most standard high moisture corn inoculants were developed to improve fermentation. For this reason, aerobic stability during and after feed-out may not be significantly improved. In fact, some standard lactic acid producing bacterial inoculants may actually improve fermentation but decrease aerobic stability (heating at feedout). With all 3 inoculants, it is important to follow the manufacturer's application rates. Typical rates are between 100,000 and 500,000 colony forming units (cfu) per gram of high moisture corn.

Lactobacillus buchneri

Lactobacillus buchneri is a unique bacterial inoculant that has been developed to improve aerobic stability of silages and high moisture corn by reducing the growth of yeasts. The net result is grains inoculated with L. buchneri are more resistant to heating when exposed to air as compared to untreated silages. L. buchneri was originally isolated from naturally occurring aerobically stable silages. It is a heterofermentative bacteria that produces both lactic and acetic acid during fermentation. Silages treated with an effective dose (600,000 CFU/gram of wet corn) of L. buchneri have higher concentrations of acetic acid and lower levels of lactic acid than untreated silages.

The beneficial impact of L. buchneri appears to be related to the production of acetic acid. Although the precise mechanism has not yet been determined, it is likely that aerobic stability is improved because acetic acid inhibits growth of specific species of yeast that are responsible for heating upon exposure to oxygen. As a result, the temperature of fermented feed inoculated with L. buchneri does not readily rise upon exposure to air and tends to remain similar to ambient temperature for several days, even in warm weather. Using L. buchneri often results in a slightly higher dry matter loss during fermentation compared to standard homofermentative bacterial inoculants.

L. buchneri is a well-researched, highly effective inoculant to use for high moisture corn preservation in all storage units. Use of L. buchneri improves aerobic stability and this is important if high moisture corn removal rates need to be reduced because of mycotoxins or excessively degradable starch.

Propionic acid

Preserving high moisture corn with propionic acid or propionic acid mixtures (propionic, acetic, benzoic) has been a proven effective practice for many years. However, it is more costly than simply using a standard inoculant and requires specialized equipment to apply. There are several situations where the use of propionic acid to reduce pH and preserve corn makes good sense. In years past, some producers have successfully used concrete or wood floors/bins to store high moisture corn. In this case, it's a must that corn be treated with propionic acid. Applying propionic acid at the proper rate reduces the pH of preserved corn to about 4.0 and inhibits the growth of harmful microorganisms. The cost of treatment is usually comparable to that of on-farm drying.

The proper application rate depends on two factors: 1) the moisture content of the grain, and 2) the intended length of storage. Rates are based on pounds of actual acid. It's most economical to treat corn with acid when kernel moisture is near 30 percent. It typically takes 10 to 20 lbs. of actual acid to fully preserve a ton of high moisture corn.

Another situation where acid may prove beneficial is when an upright silo is being filled but not fed from for an extended period of time. In this case, producers often only apply acid to corn that will fill the last 5 to 10 feet at the top of the silo. It is at the top where spoilage is most likely to occur as a result of oxygen infiltrating the grain. Again, determine rates based on length of storage and moisture.

Nutrient Content and Feeding Recommendations

High moisture feedstuffs have different feeding characteristics compared to similar dry feeds. High moisture corn ferments faster in the rumen than dry corn and traditionally was thought to add to the difficulty of getting animals started on feed and offer slightly less performance especially early in the feeding program. Currently, the popularity of corn distillers grain and corn gluten feed programs have minimized or eliminated that concern. The lower starch content of corn co-product based diets decreases the risk of rumen acidosis. High moisture corn may be more valuable in modern corn co-product diets than in traditional corn pellet diets. Combinations of dry corn and high moisture corn offer 5 to 10 percent greater weight gains and feed efficiencies than either one alone.

High moisture ear corn offers 6 to 10 percent greater feeding value than dry ear corn. High moisture ear corn and snaplage include a digestible fiber portion and a rumen effective fiber portion that helps meet the roughage needs of the animals.

The energy content of high-moisture corn is similar to dry-rolled corn. However, high-moisture corn typically has higher ruminal and total tract digestion than dry-rolled corn. The higher ruminal digestion rate means producers need to pay particular attention to bunk management when feeding high-moisture corn.

Proper bunk management includes taking care to thoroughly mix all ingredients in the ration, including ionophores or other supplements; feeding at the same time each day; adjusting feed delivered to intake of the animals; and observing cattle for signs of acidosis or feed refusal.

In addition, because of its moisture content, high-moisture corn is prone to more rapid deterioration in the bunk than dry-rolled grain. In addition, increased spoilage losses can occur during storage, especially during the summer, if the high-moisture grain is not properly packed, covered and managed.

Immature corn may be harvested effectively as high-moisture corn for feed. Research indicates light-test-weight, immature corn harvested and fed as high-moisture grain produced equal performance as mature corn grain in feedlot steers. Analyze grain for nutrient content to more accurately formulate rations because light-test-weight corn often contains more protein than heavy corn.

Pricing High-moisture Corn

When pricing corn, producers should take into account differences in moisture level, particularly with high-moisture corn. Dry corn typically is traded at 15.5 percent moisture. High-moisture corn can have moisture levels from 24 to 33 percent, which necessitates adjustment to a constant moisture level. A useful series of calculators and apps to make this conversion can be found here.

Summary

For beef cattle and dairy producers, harvesting corn as high-moisture grain offers many advantages. Nutrient content and moisture of high-moisture corn may vary depending on harvest timing, yield, variety and other factors. To reduce storage and spoilage losses, proper processing and storage recommendations should be followed with particular attention to kernel processing, oxygen exclusion/proper packing and covering bunker silos to reduce spoilage. Take care when feeding high-moisture corn because it does have a faster ruminal digestion rate than dry corn. Consequently, better bunk management typically is required for successful feeding.

High Moisture Corn, Ear Corn and Snaplage