Current Progressive Dairy digital edition

7 common forage storage myths

Troy Brown for Progressive Dairyman Published on 08 August 2016

Growing and storing forage is something people have been doing since the beginning of agriculture. Many practices and beliefs have been passed from one generation to the next, leading to common misconceptions in the industry.

Below are seven common myths about storing forage and the real facts to help you optimize your forage management decisions.



Myth #1: One storage type is better than others.

FACT: All forage storage units have strengths and weaknesses.

There is no such thing as a “perfect” forage storage unit. There may be a better solution for your particular management style or operation size, but each type will require some form of management. You must determine which storage will work best for your needs and fit your management capabilities.

Myth #2: All silage heat is bad.

FACT: There are two distinct types of forage heat: physiological heat (helpful) and microbial heat (harmful).

Physiological heat is produced by plant respiration during ensiling and is required for proper fermentation. Without physiological heat, the bacteria critical for fermentation cannot thrive.

This type of heat produces temperatures in the range of 90 to 110ºF. Much of the physiological heat is trapped and retained by the silage mass. After fermentation is complete, the temperature of the silage mass will settle at about 5 to 15 degrees above the ambient temperature at which it was harvested.


Microbial heat, commonly referred to as secondary heating, is caused by aerobic organisms such as yeast and mold. Microbial heat can reach temperatures in excess of 140ºF. This type of heat is very bad and must be avoided to ensure successful storage of silage.

Myth #3: Inoculants aren’t needed if I have incorporated forage best management practices and have done everything correctly during harvest.

FACT: It is actually just the opposite; producers that incorporate forage best management practices will capture the economic benefit of inoculant technology, whereas those that do not will simply experience more expense.

Forage inoculants will make good feed better but will not make bad feed good. Inoculant technology has been thoroughly vetted and proven to be very cost-effective, with as high as a 15-to-1 return on investment.

Research has shown adding an inoculant leads to faster, more efficient fermentation. Forages treated with inoculant will produce more lactic acid, improve dry matter recovery by 2 to 6 percent and improve animal performance by 3 to 5 percent. Inoculants have great return on investment but cannot overcome bad management practices.

Myth #4: As long as I have enough packing weight, the packing procedure isn’t important.

FACT: Proper packing procedure is crucial, regardless of the type of forage.


The objective of packing forage is to extinguish air from the pile. As layer thickness increases, a “bridging effect” can occur, where weight is distributed outward rather than directly down. With less downward pressure, less air is extinguished. Fermentation is an anaerobic process and can’t occur until air is completely expelled.

Packing properly ensures even distribution of weight and adequate downward pressure, therefore extinguishing air more effectively.

Myth #5: A high dry matter density score is the best indicator of a “good” packing process.

FACT: Dry matter density can be very misleading because it does not take into account the moisture in the feed. Water is part of the storage environment, and it must be considered.

Mold and yeast require oxygen to thrive. If air is extinguished during filling and air penetration is controlled during storage, mold and yeast growth cannot thrive. Thus, bulk density and porosity are much better indicators of “good” forage packing than dry matter density. When packing, the primary goal should be to minimize porosity, which is the measurement of the voids between the solid dry matter particles.

Porosity will determine how fast and far air can travel into the open face of the silage mass. The open space can either be filled with water or gas/air. When storing feed, air is a greater enemy than moisture. When packing, aim for bulk density in excess of 44 pounds per cubic foot. Research from University of Wisconsin recommends a maximum porosity score of 40 percent.

Myth #6: Forage shrink and dry matter shrink are the same.

FACT: Shrink is a very deceptive term.

It is key to understand that forage shrink and dry matter shrink are very different and must be measured separately. A 10 percent forage shrink does not mean a 10 percent loss in dry matter. The shrink loss case study in the sidebar illustrates this point.

Myth #7: It is safe to approach the face of a well-managed forage bunker or drive-over pile.

FACT: A silage avalanche can occur at any time, no matter how well the face is managed or how safe the pile may appear.

All too often, we place ourselves and employees in harm’s way. Forage avalanches are common, and they are going to occur. It is recommended that you maintain a safe distance of three times the height of the forage mass. This means that, for a bunker that is 18 feet tall, you should be 54 feet away from the silage face.

Get the most from your forage by keeping up on the latest management techniques and technologies for storing successfully and safely.  PD

Troy Brown is a national forage quality consultant with Cargill. Email Troy Brown.

Shrink loss case study: Calculating the difference in forage