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Data Distillations is published quarterly and utilizes Rock River Laboratory’s vast database of feedstuff information from across the United States, along with our expert team, to share important insights.

In an effort to help the agriculture industry stay in front of challenges and opportunities with available feedstuffs, relevant graphs will be shared, along with what our team members are gleaning based on those graphs. Prepare for and remedy the ups and downs of feedstuffs components you utilize in your rations with the help of another set of eyes. Sign up to receive alerts when new Data Distillations are available each quarter by completing the thirty-second form at the bottom of this page or click the link here

August 30, 2021 Insights

Author: Cliff Ocker

The Cost of Fermentation Shrink

Fermentation shrink, often referred to as Dry Matter (DM) loss, is real. Not many would argue that. And as we delve into the nuts and bolts of this phenomenon, we often talk about it in terms of percentages. But what if we assign a dollar value to fermentation shrink?

Dr. Limin Kung, University of Delaware, suggests that it is difficult to preserve a forage without seeing 10 percent DM loss. If this is true under the best conditions, how high does that loss value become for poorly fermented or poorly managed bunkers or drive-over piles?  Uniquely, Rock River Laboratory helps to try to find that answer. In 2015, Dr. John Goeser, Director of Nutrition at Rock River Laboratory, built an algorithm to calculate fermentation shrink based on the fermentation profile of individual forages. [For more information or to receive a copy of this peer-reviewed and published paper, please contact Rock River Laboratory.]

The fermentation dry matter loss (shrink) value is reported on all forages with a corresponding fermentation analysis. Note Table 1 which shares averages and ranges across feed types. Bear in mind that the fermentation shrink represents only a portion of the total shrink and the total losses are likely greater than what is reported on our Rock River Laboratory Report. This is simply because we solely use the fermentation profile to predict this value and it does not include environment and management items that could significantly add to this value.

Tying the fermentation shrink value back to dollars hit me a few years back when I was asked to help do pre-harvest meetings on a few large dairies. During the discussion of bunk management and reviewing how much silage was pushed by the pack tractor after truck unloading, we realized quickly that an additional tractor was needed to achieve the proper density. With some resistance to the need for a second tractor (because of costs), someone asked the cost of NOT adding the second tractor. 

Without knowing exactly what additional DM would be lost, what if we can improve fermentation shrink by three percent?  For the aforementioned dairy, it meant that they would need to plant an additional 150 acres of corn. The owner of the dairy proceeded to share that the additional costs associated with 150 extra acres of corn would cost him in excess of $200,000. A second pack tractor was promptly added. 

For most dairies, three percent shrink may not mean that 150 additional acres of corn silage are needed. But the fact remains that fermentation shrink typically equates to a larger dollar amount than we think. Helping a dairy or feed yard realize the true cost may help prompt more open discussion around bunk management and the use of a well-researched silage preservative/inoculant. Checking fermentation shrink is often not an additional cost as it comes as part of several Rock River Laboratory NIR packages. 

While fermentation shrink is real and quite costly, a few tips can help reduce this challenge. Try to put up a 'clean' feed. As seen in Figures 1 and 2, while ash content increases, so does DM loss. Ash acts as a buffer and elongates the fermentation process - increasing DM loss. Keeping ash/soil contamination out of forages will help in the fermentation process. Moisture also plays a huge role in how a forage will ferment. Figures 3 and 4 showcase how the higher levels of moisture lead to a more inconsistent fermentation and DM loss. However, depending on the storage type, the moisture level needs to be high enough for adequate packing to reduce oxygen levels in the forage. Reviewing management practices prior to harvest of any feed type can pay big dividends in reducing DM loss.

Table 1:  Fermentation shrink averages and ranges across feed types

Feed Type 15th Percentile Mean 85th Percentile Standard Deviation (SD)
Haylage 2.079 3.224 4.287 1.684
Corn Silage 1.383 2.448 3.472 1.980
Small Grain Silage 1.954 3.982 5.150 4.472

Figure 1: Fermentation shrink vs. dry matter for hay

Higher ash content in forage increases fermentation shrink. 

Plot of Fermentation shrink vs. ash in hay from Rock River Laboratory samples

Figure 2: Fermentation shrink vs. dry matter for small grain silage

Higher ash content in forage increases fermentation shrink. 

Plot of Fermentation shrink vs. ash in small grain silage from Rock River Laboratory samples


Figure 3: Fermentation shrink increases as soil (ash) contamination increases in the hay crop


Plot of fermentation shrink vs. dry matter in the hay crop from Rock River Laboratory samples

Figure 4: Fermentation shrink increases as soil (ash contamination increases in small grains silage) 

Wetter forages may require more management as Rock River Laboratory data demonstrates less consistency around fermentation shrink as forages are put up with higher moisture content. 

Plot of Fermentation srhink vs. dry matter in small grain silage from Rock River Laboratory samples;

July 19th, 2021 Insights

Author: John Goeser, PhD, PAS, Dipl. ACAN

Nitrate Content Questions and Database Trends

The building block for amino acids and protein in plants is nitrate-N. Think of the plant as a factory in this regard. The protein production within the plant is typically seamless when the plant has moisture and energy. However, with stressed plants,  there may be an accumulation of nitrate-N that was not incorporated into protein within the plant. Stress can occur through drought or freezing conditions. In drought conditions, particularly after a rainfall event, plants will readily absorb nitrate-N but may not have the energy and resources to build protein. In freezing conditions, the plant dies in its current production state, and unused nitrate-N is stuck within the plant. 

In either case, nitrate-N can become a concern for animal nutrition. Nitrate-N is toxic to ruminants if the concentration within the total dietary intake exceeds the rumen’s ability to metabolize the compound. Dairy and beef cattle can adapt to increasing nitrate-N concentrations in the diets, provided the nitrate-N concentration increases gradually. However, as a rule of thumb, forage and ration content greater than 1,000 parts per million (ppm) begins to be of concern and should be monitored. Nitrate-N concentrations of up to 4,000 to 5,000 ppm have been measured over the past several years, however many samples are less than the 1,000 ppm concern threshold. 

With drought conditions in the Midwest through to the south and western US, nitrate-N concentrations are being evaluated. Sorghum and other small grain silages are drought-friendly crops, however, they have also been known to accumulate nitrate-N. Figure 1 showcases the nitrate-N concentrations for populations of sorghum and small grain silages samples analyzed in four consecutive crop years. The three vertical black lines within each bell curve represent the 15th, mean and 85th percentiles, respectively.  A majority of the samples are less than 1,000 ppm, however, roughly 15 percent of samples are near 2,000 ppm. The average nitrate-N content this growing season appears to be slightly greater than the prior two years. 

Figure 1: Nitrate-N concentration for sorghum and small grain silage samples analyzed by Rock River Laboratory, Inc. the past four crop years.

Figure 1: Nitrate-N concentration for sorghum and small grain silage samples analyzed by Rock River Laboratory, Inc. in the past few crop years.

In Figure 2, similar graphics detail the nitrate-N concentrations for hay crop samples throughout the US over the past four growing seasons. Hay crop samples are substantially less contaminated than the sorghum and small grain silage samples.

Figure 2: Nitrate-N concentration for hay crop samples analyzed by Rock River Laboratory, Inc. the past four crop years.

Figure 2: Nitrate-N concetration for hay crop samples analyzed by Rock River Laboratory, Inc. over the past four crop years.

If your forage turns out to be high in nitrate-N, there are options to work with the feed. If testing green chopped or fresh forage, consider fermenting the forage through balage or haylage, understanding that fermentation will lessen the nitrate-N level through microbial activity and growth during the ensiling process. Green-chop and fresh forage will also release the nitrate-N more slowly than dry hay forage. Consider adding the forage to the diet in slow and incremental fashion, while paying close attention to animal health and test the forage as close to the time of feeding as reasonably possible. Ultimately, work with your nutritionist to determine how to best utilize nitrate-N contaminated forage.

June 11th, 2021 Insights

Author: Katie Raver

New Year, New Forages

Many farms have implemented cool season forages such as rye, wheat, and triticale as these nutrient-rich cover crops can also help to maximize total tons of feed harvested per acre each year. In years like 2021 when commodity prices are much above average and drought conditions exist across many areas, cool season small grain forages are a huge asset to farms.

As the heart of the harvest of these feeds begins, what trends are we seeing in fresh samples so far? First, let’s take a look at fiber quality. Total Tract Neutral Detergent Fiber Digestibility (TTNDFD) is a fantastic tool that uses multiple fiber digestibility parameters to give a more complete estimate of apparent total tract digestibility. It can also be used to compare different forages using this one value - offering insight on how fiber digestibility will compare across feeds such as corn silage or even dry hay.

Ridge plots showing distribution of Total Tract NDF digestibility (TTNDFD) of fresh (pre-ensiled) cool season grasses over the past three years.

Figure 1. Ridge plots showing distribution of Total Tract NDF digestibility (TTNDFD) of fresh (pre-ensiled) cool season grasses over the past three years.

To date, this year’s crop looks to have similar or higher TTNDFD for triticale, wheat, and rye versus the 2020 crop. For rye in particular, the TTNDFD distribution looks to have shifted higher compared to 2020 samples. On average TTNDFD in rye and triticale is 2.5 percent higher than in 2020, whereas TTNDFD in wheat is similar to 2020 values. These values indicate more potentially digestible fiber which can allow more efficient and potentially higher milk production. According to Dr. Dave Combs of the University of Wisconsin-Madison, a two to three unit increase in TTNDFD supplies enough energy to account for one pound additional milk production.

Protein is in the hot seat this year as prices of many protein commodities have increased over 30 percent compared to last year. Moderate to high crude protein (CP) levels are a huge benefit of cool season small grains silages, and in years when commodity prices are high, taking advantage of the CP in these forages can have a large impact on the bottom line. 

Ridge plots showing distribution of Crude Protein in fresh (pre-ensiled) cool season grasses over the past three years.

Figure 2. Ridge plots showing distribution of Crude Protein in fresh (pre-ensiled) cool season grasses over the past three years.

While wheat seems to show the most consistent protein levels over time, CP levels in rye and triticale crops harvested to date are both higher than 2020 and 2019. Values, on average, for these crops are approximately one to two units higher than previous years. If ten dry matter (DM) pounds of these crops are fed, one additional unit of CP would contribute an extra 0.1 pound. of CP - which in today’s market can equate to anywhere from two to four  cents (phpd). Due to high protein prices, extra care should be taken to ensure proper ensiling to reduce the risk of protein quality loss.

Keep in mind that certain crops may also be better suited for certain areas, and nationwide trends may also be different than regional trends. Figure 3, below, shows regional differences between TTNDFD and CP content in rye, wheat, and triticale in 2021.

Regional differences in nutrient content of rye, wheat, and triticale in 2021 fresh samples.

Figure 3. Regional differences in nutrient content of rye, wheat, and triticale in 2021 fresh samples.

Bottom line: every crop year is a little different than the one before, but testing feeds as they go into the pile can give us more information on what is to come as we feed out the pile. In years where dairy producers are faced with many challenges, such tools can help make decisions that positively impact the bottom line.

March 23rd, 2021 Insights

Author: Cliff Ocker

Energy out the A$$

Starch digestibility is often watched quite closely in our diets today as we formulate rations and work to feed more efficiently. We continue to learn more about starch digestibility, yet at times still struggle with the results. The 2020 crop year has been variable across the country as we look at data within the Rock River Laboratory database. We also see that, while typically fecal starch by this time of year has dropped below two or three percent, this year, we still are bumping against five percent fecal starch, as shown in Figure 1.

Figure 1: Fecal Starch Over Time

Dairy fecal starch results from Rock River Laboratory, plotted

Dr. Jim Ferguson, University of Pennsylvania, suggests that every point of starch over three percent in fecal samples for high producing cows equates to .72 pounds of milk.  This would suggest that, on average, there is about a pound and a half of missed opportunity milk that is still adding costs to the diet.  Fecal starch is a quick and easy way to see how well the cows are utilizing the starch being fed. Making adjustments to the diet when and where needed can help efficiency. Figure 2 shows an example Fecal Starch report. Of note: Rock River Laboratory can provide this report for dairy, beef and calves.

Figure 2: Sample Dairy Fecal Starch Report 

Example Rock River Laboratory Fecal Starch Report

Rock River Laboratory continues to find innovative ways to look at data and visualize trends and variation. It is interesting to look at the 0-hour time point for corn silage for the 2020 crop year versus the 2019 crop year across different regions of the country – as noted in Figure 3 and 4. This measure represents very rapidly digestible starch, that goes into solution with water. Think of it like starting fluid for a diesel engine. In the 2019 crop, we saw this rapid starch digestibility measure move from 20 percent to 30 percent for much of the country, over the course of a year. Meanwhile, the 2020 crop appears to be more variable by region. While there may be a number of reasons for this, it may help explain milk production and/or components by region as well.

Figure 3: 2019 Corn Silage '0' hour Starch Digestibility

isSD0= in situ starch digestibility at '0' hour

Corn silage 0-hour starch digestibility from Rock River Laboratory, plotted

Figure 4:  2020 Corn Silage '0' hour Starch Digestibility

isSD0= in situ starch digestibility at '0' hour

Rock River Laboratory corn silage 0-hour starch digestibility over time, plotted

Taking time to gather this type of information on your dairies can help explain the effects you’re seeing, and allow for greater feed efficiency to help improve income over feed costs (IOFC) for your producers.

January 21st, 2021 Insights

Author: John Goeser, PhD, PAS

The corn silage heartbeat

Your corn silage has a heartbeat. This may seem a bit odd at first, but every year corn silage comes alive with more energy - much like your heartbeat provides your body with the oxygen and energy needed to get the job done. In the case of corn silage, the heartbeat stems from starch. 

Starch in corn silage comes from the ear and grain, providing 50 percent or more of the total digestible nutrient content in every ton of silage. Starch content varies from year to year, in alignment with grain yield. In Figure 1, recognize that producers are raising greater grain yields in the last couple of years - relative to five years ago. 

Figure 1: Corn silage starch content, as a percent of dry matter, for samples submitted to Rock River Laboratory over the past five years

Graphic plot of strch for Corn Silage from Rock River Laboratory database

Starch and fiber each typically make up around 30 to 40 percent of the dry matter in corn, however, the energy coming from starch is greater due to starch being twice as digestible as fiber. With that being said, starch digestibility greatly fluctuates. Therein lies the corn silage heartbeat. Just like your heartbeat increases blood flow and pressure, starch digestibility and rumen digestible starch content in silage increases in a rhythmic pattern. The silage heartbeat ties to new crop silage, as detailed in Figure 2. Notice how the in situ rumen starch digestibility drops on an annual basis, as new corn silage starts to be fed. This dropoff represents a lower energy crop initially, but one that improves as the silage ferments and the starch becomes more digestible. 

Figure 2: Corn silage rumen starch digestibility, as a percent of dry matter, for samples submitted to Rock River Laboratory over the past five years

Graphic plot of isSD7 for Corn Silage from Rock River Laboratory Database

An alternative way to think about the silage heartbeat is to combine starch content and digestibility into rumen degradable starch, as a percent of dry matter. Nutritionists and producers are now looking at rumen degradable starch on a dietary basis, but we can also look at this on a silage-only basis. Figure 3 details rumen degradable starch in silage over the past five years. We can see that rumen degradable starch is low each year after harvest but improves with several months in the silo. This drop means that a 30 percent starch silage may only feed like a 20 or 25 percent starch silage, as the rumen is not able to capture the full starch value until the silage fully ferments and the starch softens. 

Figure 3: Corn silage rumen degradable starch (RDS) content, as a percent of dry matter, for samples submitted to Rock River Laboratory over the past five years

Graphic plot of RDS for Corn Silage form Rock River Laboratory Database

Check your silage’s heartbeat and ensure you account for the factors discussed, in your ration.

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