Welcome to the Spring 2000 Forager

elcome to the Fall 2000 Forager. We have just finished with the 2000 WFC Forage Expo in Stanley. By all accounts, the event was a huge success. We are estimating more than 500 attendees. The weather was perfect, and the Chippewa Valley Forage Council did a great job organizing the event. Thanks and congratulations to all who worked to put this show together!

Thanks also to all those who helped the WFC host the joint American Forage and Grassland Council/North American Alfalfa Improvement Conference meeting in Madison in July. That meeting was a great success with one of the largest turnouts ever.

We now turn our attention to the WFC Forage Symposium in Eau Claire January 23 and 24. The Board of Directors along with the Chippewa Valley Forage Council are putting together a good program, and we are anticipating another successful meeting. The symposium will take place at the Ramada Inn in Eau Claire. We hope you plan to be there!

Tracking Corn Silage Drydown

Corn silage harvest will likely arrive prior to your receiving this, but here is a reminder that corn silage moisture for many areas of Wisconsin can be tracked on the World Wide Web at http://cf.uwex.edu/ces/ag/silagedrydown/. Whole plant moisture is the most reliable way to determine optimum corn silage harvest time, and this site can assist in determining that.

Bob Eder Wins

AFGC Spokesperson Contest

Congratulations to Bob Eder, dairy producer from New London on winning the 2000 American Forage and Grassland Council Forage Spokesperson Contest in Madison. Bob was the winner of the WFC Spokesperson Contest and competed in Madison against contestants from all across the country. Bob is our second winner in the past four years. All of our contestants do a great job representing Wisconsin forage production and we thank them all for their hard work and time.

Introduction

Various spoilage microorganisms (bacteria, yeasts and molds) readily grow on crops going into a silo, causing losses in dry matter and quality. To prevent these various microorganisms from growing, two conditions are needed in the silo: an oxygen-free (or anaerobic) environment and a low pH. Many of the oxygen-requiring (aerobic) microorganisms that heat the silage as well as causing losses cannot be stopped by low pH alone. These microorganisms can only be stopped by sealing the silo well to keep out air. On the other hand, bacteria responsible for poor fermentations such as clostridia are stopped by dropping the pH of the crop sufficiently to prevent their growth.

The lowering of silage pH happens naturally under most circumstances. This is due to lactic acid bacteria on the crop fermenting sugars to lactic and acetic acids as well as to alcohol and several other minor compounds. Lactic acid is the preferred product of fermentation because it is a strong acid. Lactic acid also contains almost the same energy as the original crop sugars, and it can be fermented by rumen microorganisms. The speed and efficiency of the natural fermentation process is highly variable, depending on the number of lactic acid bacteria on the crop, the particular strains of lactic acid bacteria, and the temperature and sugar content of the crop.

Inoculants are silage additives containing lactic acid bacteria that have been selected to grow rapidly and efficiently (producing primarily lactic acid) on crops in the silo. Consequently, they help to insure a good fermentation in the silo. However, the primary economic benefits are in improved dry matter recovery from the silo and improved animal performance.

Are inoculants really needed on corn silage?

Inoculants have been successful less frequently in corn silage than in hay-crop silages. Research studies show that inoculant treatments lead to fermentation improvements approximately two-thirds of the time in hay-crop silages as contrasted with only 40% of the time in corn silages. There are two primary reasons for the reduced response in corn silage. First, the natural population of lactic acid bacteria on corn at ensiling is on average 10 times higher than the natural population on alfalfa. This makes it more difficult for the inoculant to overwhelm the natural bacteria in corn silage and produce an effect. Second, natural fermentations in corn silage typically are high in lactic acid, low in acetic acid, and result in a low pH (3.8-3.9). With such a good natural fermentation, it is difficult for an inoculant to make substantial improvements in fermentation.

When the inoculant does succeed in improving fermentation, reductions in bunk stability have been frequently observed in research studies. Because bunk stability is already a problem in naturally fermented corn silage, any additive that potentially makes the situation worse is not particularly attractive. Together, these factors indicate that inoculants will not be as profitable in making corn silage as in hay-crop silage. This in turn suggests that particular care in selecting and using inoculants will be required if you decide to inoculate corn silage.

Will inoculants reduce corn silage losses in the silo?

When the inoculant bacteria improve fermentation, dry matter losses from the silo decrease 1-2 percentage units on average. In other words, dry matter losses in a well-managed bunker silo would typically be reduced from 15% to 13-14% by inoculation. This decrease in dry matter loss is largely due to a shift in fermentation. There is no dry matter loss when lactic acid bacteria ferment sugar only to lactic acid. In contrast, fermentation that produces lactic acid plus alcohol or acetic acid results in up to a 24% loss of the original sugar.

Will inoculants improve bunk stability of corn silage?

While these products are often marketed as improving bunk stability, research studies show that inoculants generally have little effect on this aspect of silage quality when considering all ensiled crops. The reason for this is the inoculant’s effect on fermentation. Both lactic and acetic acids (primarily acetic acid) help inhibit the growth of spoilage microorganisms that cause heating in silage. Thus reducing the acetic acid content has a negative effect on bunk stability. However, lowering pH makes the acids present in silage more effective at inhibiting spoilage microorganisms. In corn silage, it is difficult for an inoculant to produce a much lower pH than that from a natural fermentation. The net result is that bunk stability in corn silage is often reduced relative to that produced by a natural fermentation. Inoculant manufacturers are aware of this problem and are working to develop new inoculants that resolve this problem. Several new corn silage inoculants are available, but there are insufficient data at present to know if they consistently improve bunk stability.

Will inoculants increase corn silage digestibility and intake?

The shift in fermentation produced by inoculants should increase silage digestibility similarly to the improvements in dry matter recovery. In addition, research has documented that at least several products have improved fiber digestibility. The reason for this is not known. These improvements in digestibility have not always led to improvements in intake. A recent survey of inoculant studies in all silage crops found that intake was improved in only 21% of the animal studies whereas as fermentation was improved in 60% of the cases.

Will corn silage inoculants increase milk production?

Increases in animal performance have been observed more often than increases in intake. A recent survey of inoculant studies in all silage crops found milk production improved in about half of the studies. In studies where milk production was improved, milk production increased on average 3 lbs/cow/day. While most of the studies were with hay-crop silages, similar improvements are likely in corn silage.

Under what conditions will a corn silage inoculant be most successful?

We know much less about variation in the population of naturally-occurring lactic acid bacteria on corn than we do on alfalfa. Typically, the average population on corn at harvest is 10 times higher than on alfalfa so that inoculants are less successful on corn silage. Times when an inoculant is more likely to be successful are in immature corn, overly dry corn, and the day after a killing frost. The limited research data available suggest that these may be conditions where the natural population may be lower and/or less competitive than the inoculant bacteria.

What is the correct application rate?

The labeling of inoculants is highly variable and makes comparing products difficult. What is important is the number of lactic acid bacteria applied per unit of crop. One should buy a product that applies at least 90 billion live lactic acid bacteria per ton of crop as fed or 100,000 per gram of crop. Some products tell you how many bacteria are in the bag or bottle. In those cases, you will need to calculate how many will be applied to the crop. Higher numbers than these minimum rates should be better but are not always so.

What organisms should be present in a silage inoculant?

Inoculants may contain one or more strains of lactic acid bacteria. The most common is Lactobacillus plantarum. Other Lactobacillus or Pediococcus species may be present; also Enterococcus faecium is common. Rarely, a Bacillus species may be present to improve bunk stability. Be skeptical of products that contain other species.

Are there performance differences between specific strains of an organism?

Yes. For example, not all Lactobacillus plantarum strains grow at the same speed. Some L. plantarum strains may grow better on alfalfa, others better on corn. Some strains may grow better under drier conditions or higher temperatures than others, etc. Because of these differences, it is important to use a product labeled for the crop that you are ensiling. If a product is labeled only for corn silage, don’t use it on alfalfa and vice versa.

Is there a performance difference between dry and liquid products?

Both dry and liquid products can be effective, but liquid application has some advantages over dry application. First, these bacteria cannot move around. They grow where they are placed. Therefore, inoculants must be applied as uniformly as possible to maximize effectiveness. A liquid sprayed on the crop at the chopper provides the best opportunity to distribute the inoculant uniformly and mix it thoroughly with the crop. Second, the bacteria in a liquid product should be able to begin working faster than a dry product, where the bacteria need to be moistened by plant juices before they can begin to grow. Third, most inoculants need to be kept cool and dry prior to use in order to maintain the activity of the bacteria. This is easiest with the liquid applied products that come in small packages that can be placed in a refrigerator.

There are two issues of concern in using liquid products. First is the water used for diluting the product. If your water supply is chlorinated, the chlorine can kill the lactic acid bacteria if the chlorine level is too high. Use a pool tester to be sure that the chlorine concentration in the water is less than 1 ppm. If it is above 1 ppm, either allow the dilution water to sit open to the air overnight (so that the chlorine level is reduced), or look for a product that has compounds to neutralize the chlorine. Second, once a product has been diluted, it generally needs to be used within a 24-h period. Some products are diluted the night before use; these should be used within 24 h of when they are ready for application. Consequently, there can be some product wastage if the amount harvested is less than expected due to weather, breakdowns, etc.

How can I tell if I am purchasing a good product?

It is difficult to compare one inoculant with another, but there are some things to look for in purchasing a product. First, look for a product that guarantees to supply at least 90 billion live lactic acid bacteria per ton of crop. Second, be sure to buy a product that is labeled for corn silage.

Introduction

Silage is covered for two primary reasons. First, covered silage reduces exposure to oxygen. Oxygen is required for the growth of aerobic organisms. These aerobic organisms cause the decomposition of valuable feed. A second reason for covering silage is to exclude rainfall. Precipitation washes organic acids and other soluble feed components from the forage. Organic acids keep silage pH low resulting in an environment that prevents growth of silage-decomposing organisms. In addition, precipitation introduces oxygen to the feed.

Seepage caused by either high-moisture forage or precipitation carries away valuable feed nutrients and increases the risk of surface and groundwater contamination. Bunker silo covers should be selected based on their ability to exclude both air and precipitation.

What is the best material for covering a bunker silo?

Research and on-farm experience has shown 4-6 mil thick plastic containing ultraviolet light protection works well to exclude air and precipitation. Precipitation runoff from the bunker silo cover should be diverted without passing through the silage (often a problem at the bunker walls). Plastic should be held in contact with the silage to keep air from moving under the plastic to get into the forage. This is often done with waste tires or tire sidewalls. The tires should touch each other to obtain good, uniform weighting. Soil or sandbags are often used to seal the plastic edges.

What bunker cover alternatives provide protection for silage?

A variety of materials have been used on farms as an alternative to plastic covers. Some of these materials have been researched to study their effectiveness at preventing silage from spoiling. Producers often judge effectiveness by the depth of the spoilage layer (blackened forage) and the convenience of using an alternative cover. Extreme caution should be used when considering producer's claims of alternative cover performance. Most producers don't understand that one inch of black forage may have been 2-3 inches of green, high quality feed when placed into storage. This represents a 50-65% loss of dry matter. They also don't understand that there is a transition zone (1-2 feet) of brown-gray forage below the black layer where a substantial amount (20-30%) of dry matter loss occurs. Research has shown that covering silage with ground limestone or soil may provide some silage protection compared to no cover at all. However, unless a cover excludes air and water, it does not compare very well to plastic covers. Research has also shown that covering silage with molasses, "nutri-shield", sawdust, sod, or a roof only does not protect against spoilage loss any better than if the silage remains uncovered.

Are there any spray-on products that can provide good silage protection?

This is the "Holy Grail" of silage covers. The concept would allow minimal effort and still provide forage protection. Several products have been developed and tested, but to date nothing has emerged as a successful product.

Introduction

Forages and total mix rations (TMRs) that begin heating after they are fed can lower dry matter intake and animal performance. Proper management during ensiling and feeding can minimize heating in the feed bunk and improve palatability.

What causes feed to heat in a bunk?

During the ensiling process, bacteria ferment silage sugars to lactic acid. The lactic acid is responsible for lowering silage pH. Any oxygen that is present in the silage mass after packing is used up in the fermentation process. The combination of low pH and lack of oxygen stabilizes the silage while it is in the silo. During feed-out, oxygen is re-introduced into the silage and yeast can become active causing the silage to heat up. Because of high yeast content and available sugars, corn and small grain silages are more prone to heating during feed-out. The tendency to heat during feed-out is also prevalent in grass or legume silage that did not ferment well.

Management options to minimize silage heating and spoiling.

Several management factors help to minimize heating and spoilage of silage that occurs after feed-out. In general, harvest management practices that promote a desirable fermentation will help to reduce post-feeding losses. These practices include:

· harvesting forages at the correct moisture content,

· chopping forage at the correct particle length,

· packing silage to a density of 15 lb DM per cubic foot and,

· covering the silo with plastic.

Along with these practices, it is recommended that the harvested forage be inoculated with a minimum of 100,000 colony-forming units (cfu) of lactic acid producing bacteria at ensiling. This usually improves silage fermentation and in some cases may improve bunk life. However, bunk life is often not improved in silages with a very high lactic acid content such as corn silage. Lactic acid is an energy source for yeast fungi and can promote a fast yeast buildup in silages during feed-out. High levels of yeast activity lead to heating of fed silage.

To enhance the bunk stability of corn silage, anhydrous ammonia can be added during the ensiling process. However, the use of anhydrous ammonia may actually reduce DM recovery from the silo. The recommended rate of application is 7 lb per ton of 35% DM corn silage. All safety precautions must be followed when using anhydrous ammonia.

Another option for improving bunk life of fed silage is the use of proprionic acid based products. These commercially available products reduce the growth of yeast and molds in silage when added during the ensiling process. These products often contain some acetic acid or benzoic acid to make them more effective against yeast. Since these are buffered-acid products, corrosion of harvesting equipment or blowers is not a concern. These products are usually added at a rate of 2-4 lbs/ton of 35% DM silage. Because of cost, their use at ensiling has been limited, but their use at the time of TMR mixing is becoming more common.

Finally, removal of sufficient quantities of silage from the silo each day to keep the face or surface cool is extremely important. Silage needs to be removed evenly across the whole face or surface of the silo. A minimum of 6 inches of feed (or enough to keep the face cool between feedings) should be removed each day to minimize oxygen exposure and keep feed fresh. Any feed that is loosened during feed-out but left in the silo has been exposed to oxygen and it could start to heat. So, keep the face even and tightly packed and feed up any loose silage.

Managing TMR mixes to minimize heating?

Manage the wet feed ingredients (i.e. silage, wet brewers grains, corn gluten feed, etc.) that will be added to the TMR to minimize heating in them. "Hot" ingredients added to a TMR will cause it to heat up in the bunk. "Hot" ingredients that can not be controlled may need to be fed as a lower proportion of the mix or removed from the TMR. Prepare the TMR mix just prior to feeding it. Mixing a TMR and allowing it to sit over night before feeding will allow it to heat up.

Keep a clean bunk. Remove all feed refusals daily before any new TMR is fed. To keep the feed fresh in tie-stall barns, use manger liners and drinking cup anti-splash guards, and ventilate the barn properly. Feed a sufficient number of times each day to keep the feed in the bunk cool. Frequency of feeding often needs to be increased during hot, humid weather patterns.

Are there products that can be added to the TMR to reduce heating?

A number of propionic acid based products are available that reduce growth of yeast and molds when added to the TMR. By reducing the potential for yeast and mold growth, bunk life may be enhanced. These products often contain some acetic acid or benzoic acid to make them more effective against yeast. Since these are buffered-acid products, corrosion of the mixer is not a concern. These products are typically added during mixing time at rates of 2-4 lbs/ton of TMR. They usually cost about $1.00 per lb. or about $0.15 per cow per day. Because of high cost, these products are typically used only during the summer or when "hot" ingredients are being added to the TMR.

Volume 24, Number 3, September 2000

Pages 2-4 Inoculants for Corn Silage

Page 5      Bunker Silo Cover Alternatives

Pages 6-7 Improving Forage and TMR Bunk Life

Page 8      What Happens if I Just Leave my

                  Last Cutting Stand in the Field

Volume 24, Number 3, September 2000

Pages 2-4 Inoculants for Corn Silage Page 5 Bunker Silo Cover Alternatives Pages 6-7 Improving Forage and TMR Bunk Life Page 8 What Happens if I Just Leave my Last Cutting Stand in the Field

Pages 2-4 Inoculants for Corn Silage

Page 5 Bunker Silo Cover Alternatives

Pages 6-7 Improving Forage and TMR Bunk Life

Page 8 What Happens if I Just Leave my

Last Cutting Stand in the Field