Every input a producer uses to harvest and store silage has increased in price, including fertilizer, fuel, plastic, seed and rent. This has increased forage values dramatically.

Recently, Vita Plus analyzed each component for feeding dairy cows and broke them into the following categories: forage, corn, proteins/fats and mineral.

Looking at a two-year period of January 2006 to April 2008, forages have accounted for the largest percent increase on a cost per cow per day basis of 41.7 percent.

Due to the large increase in forage value, producers are asking, “How should I manage my forage during storage to help reduce the amount of shrink, dry matter (DM) loss and feed waste that I have each year?”

Let’s look at some of the new management practices for bunkers, pits and piles.

Starting with the ensiling process, proper fermentation requires anaerobic conditions (without the presence of air).

A good inoculant which has been tested to withstand packaging, storage and survivability in solution during chopping will enhance the right microbial population to dominate and produce high amounts of lactic acid. Lactic acid is the primary acid for decreasing the silage pH and maintaining stability.

Research has proven that microbial inoculants are beneficial as they improve silage fermentation which results in high DM, nutrient recovery and improved animal performance.

The lack of air will prevent the growth of yeast and molds, and the low pH will help prevent the increase of other bacteria after fermentation is finished.

Because it is important to minimize and prevent air from entering the storage structure, there needs to be a lot of attention placed on sealing a bunker, pit or pile.

Bolton and Holmes summarized data on different covers including soil, candy, lime, a roof, molasses, molasses-based products, sod, sawdust, chopped straw and composed manure solids.

In all cases, none offered adequate protection against the infiltration of air; plastic and tires have continued to do the best job in controlling surface spoilage.

Covers
For years, standard 5 to 6 mil (125 – 150 micrometers [µm]) thickness black plastic or white on black plastic has been the cover of choice in the U.S. and throughout the world.

Because of the increases in forage production costs, there is increased interest in oxygen barrier film (OB film). OB film was first introduced at the XII International Silage Conference.

This OB film is a triple co-extruded film comprised of two outer layers of polyethylene, with a central layer of polyamide. It has been used in the food packaging and horticulture industries for sterilization of soil. It is 1.8 mil (45µm) in thickness and is manufactured by Industria Plastica in Monregalese, Italy.

Tests conducted at Michigan State University compared the differences between regular 5 mil white on black plastic and OB film to show oxygen transfer rates differences between the two silage covers (see Figures 2*, 3*).

There are extreme differences in the amount of air that transfers between these plastics. When put to the test on farms, Kansas State University researchers compared 6 mil black plastic to OB film in two field trials – one on whole-plant corn and the second with high-moisture (HM) corn.

Results showed dramatic differences; there was no visible discoloration or surface spoilage under the OB film, but there was mold and aerobic deterioration under the black plastic, especially in the top 12 inches. Additional proof lies in the significant improvement of fermentation profiles under the OB film.

Using all data mentioned, let’s put some of today’s economic values into use for both haylage and corn silage and the savings in using OB film.

Values used in this example include $55 per ton for corn silage (10 times the price of corn) and a hay value of $200 per ton for 85 percent dry matter.

Therefore, sealing a bunker with 10,500 tons of corn silage with OB film versus regular plastic would give us a net savings of $10,670 dollars or a 3.5-to-1 return on investment. In the same size pile, but using haylage, the use of OB film would yield net savings of $17,230 dollars and a 5-to-1 return on investment.

Other practices
There are other management practices that you can implement in your forage system that will help your storage system reduce shrink as well. They include:

1. Increase the packing density within your structure, to achieve more than 15 pounds of dry matter (DM) per cubic foot.

2. Cover your storage unit immediately, and cover as you fill. Once you are done in a location, cover right away so fermentation can be jump-started. This will also reduce your weather risk and decrease the overall task of covering when the structure is full.

3. Seal around the outside perimeter with gravel bags or limestone. This provides a more effective seal than tires by providing additional weight on the edge where it is needed.

a. Use gravel bags on all seams and overlapped sections of plastic. Sheets should overlap 4 to 6 feet.

b. Use tires between rows of gravel bags to provide additional weight on plastic.

4. To reduce the risk of water penetrating your structure, shape, face and slope your forage correctly to help reduce losses.

5. Use a facer on your silage mass to prevent air from infiltrating during feedout.

6. Use gravel bags on the leading edge of the face to prevent air from penetrating under your plastic.

7. Prevent and protect your structure from rodents, varmints, etc. by keeping the area clean, waste removed from the area and keep it trimmed. Keep a roll of bunker/tarp tape handy to reseal all holes as soon as possible.

8. Be safe! Always pack in a safe manner. Always be aware of possible silage avalanches; never build a structure where you can’t reach the top.

With the use of the new OB film and better storage management, you can dramatically reduce your shrink and feed waste on your bunker, pit or pile. This equates to higher quality feed, larger inventories and higher profitability at all times, but especially during times of high feed prices.  FG

References omitted but are available upon request at editor@progressivedairy.com

Table and Figures omitted but are available upon request to editor@progressivedairy.com.

Brian Vaassen
Vita Plus
Forage Products
Manager