Data Distillations
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.
May 9th, 2023
Author: John Goeser, PhD, PAS
Corn grain trending harder
Starch digestibility in starch-rich feeds is increasingly recognized to affect dairy and beef performance, feed conversion efficiency, and farm profitability. Dairy and beef nutritionists will readily assess corn silage, high moisture corn, or snaplage starch digestibility using rumen in situ starch digestibility measures, with a 7h rumen incubation period. Commercial feed analysis near-infrared reflectance spectroscopy (NIRS) models have sufficiently evolved to accurately measure starch digestibility as impacted by growing environment, seed genetics, plant nutrient metabolism and health, and fermentation extent.
Each of these factors is known to have an impact on starch digestibility, and in situ rumen starch digestibility NIRS models help farmers benchmark their feeds while making nutrition adjustments to improve profitability. Dry ground corn grain starch digestibility is not affected by fermentation, given none has occurred. However, shelled corn hardness and starch digestibility can be influenced by seed genetics, plant nutrient metabolism and health, and growing environment. NIRS in situ rumen starch digestibility models are also robust for dry ground corn.
Historically, yellow No. 2 corn has been assumed a commodity. Feed library values have driven diet formulation and feed purchasing decisions. Thanks to commercial feed analysis advances and more farmers testing their grain, consistency in commodity corn grain is being questioned. Meaningful deviations in nutrient content and starch digestibility have been uncovered on a case-by-case basis. Now, with thousands of dry corn analyses over the past three crop years to draw insight from, an impactful trend has come to light. The 2021 and 2022 crop years’ dry ground corn is less digestible.
Figures 1 and 2 demonstrate the population distributions for starch content and in situ rumen starch digestibility with dry corn samples analyzed by Rock River Laboratory for the Midwestern and Eastern US regions. Notably, there is slightly less starch content in 2022 and 2021 crop years, relative to 2020 corn. More importantly, though, the corn grain in situ rumen starch digestibility is lagging behind, with 2022 corn around 10 percent less than 2020 corn.
Figure 1: Dry ground corn starch content, % of dry matter, for thousands of samples analyzed by Rock River Laboratory over crop years 2020, 2021, and 2022 for Midwestern and Eastern US.
Figure 2: Dry ground corn in situ rumen starch digestibility, 7h, % of starch, for thousands of samples analyzed by Rock River Laboratory over crop years 2020, 2021, and 2022 for Midwestern and Eastern US.
Do not assume that commercial dry ground corn is a consistent commodity. Rather, consider checking your corn quality and discuss the impact that measured corn grain quality and digestibility have, relative to feed library benchmarks. Corn grain is increasingly valuable, and decreasing corn grain particle size can help offset less digestibility. Future data distillations will discuss corn grain particle size and revisit the relationship with rumen starch digestibility.
April 3rd, 2023
Author: Cliff Ocker
Don't Overlook the Opportunities with Small Grain Silage
As spring has sprung, those with livestock look to planting and harvesting crops for another year. One of the first in the new crop season will be small grain silage. Interestingly, looking at lab data, this crop tends to be quite variable in terms of quality. Several reasons exist for that but consider ahead of time what your goal is for this feedstuff and maximize the harvesting opportunity.
Small grains can be planted as a cover crop, double-cropped for extra forage for dairy or beef, or to let go to harvest the grain. Whatever the plans for this crop, it is best to know ahead of time what quality of feed is sought as this crop can change quite rapidly. Likely, the biggest influencer of quality for small grain silage is maturity. If seeking more tonnage vs a high-quality dairy forage, the timing to make it may be different.
Looking at crop year data over the past three years, similar quality swings within crop years can be seen. Figure 1 shows Total Tract NDFD (TTNDFD) for small grain silages. TTNDFD is a calculated value based on four different NDF Digestibility time points and does a better job quantifying fiber digestibility than, say, Relative Feed Quality (RFQ). The average TTNDFD of small grain silage is running in the low to mid 40’s with the lower quality samples 10 points below the average, while the best quality is 10 points above. Again, depending on the goals for the forage, this can have huge implications for livestock.
Figure 1: TTNDFD of Small Grain Silages
| Crop Year | p15 | Mean | p85 | StDev |
|---|---|---|---|---|
| 2020 | 35.98 | 44.39 | 53.85 | 7.97 |
| 2021 | 33.756 | 43.73 | 53.73 | 8.72 |
| 2022 | 34.49 | 43.09 | 52.00 | 7.88 |
Once the crop’s goal has been determined, keep an eye out for maturity, then look for a window (in the weather) to harvest the forage. Harvesting at the correct moisture is another key factor that influences not only the forage quality, but also fermentation and shelf-life. Depending on the storage type, typically a DM of between 30 and 40 percent works best. Less than 30 percent DM will typically create runoff or loss of nutrients, while over 40 percent DM can create packing challenges on this softer crop.
Putting up a clean feed is another component of high-quality forage. Soil contamination can be a major challenge when harvesting this crop since it’s cut so close to the ground. Natural ash levels in small grain silage typically run between 7 and 9 percent. Note in Figure 2 that the best (15th Percentile) ash levels are at 9 percent ash, with an average of 11 percent and many samples running above 14 percent. Ash acts as a buffer in the fermentation process, elongating fermentation and slowing the pH drop. A less-than-ideal fermentation allows molds and yeast to grow and multiply while feeding on the very nutrients that were meant for livestock consumption.
Figure 2: Ash Content Levels of Small Grain Silages
| Crop Year | p15 | Mean | p85 | StDev |
|---|---|---|---|---|
| 2020 | 9.05 | 11.37 | 13.78 | 2.35 |
| 2021 | 9.14 | 11.64 | 14.17 | 2.49 |
| 2022 | 9.26 | 11.92 | 14.59 | 2.58 |
Small grain silage can be a great crop to feed alongside or help stretch other forages further in the ration. Decide what quality of forage you would like and work to hit the correct maturity at harvest, harvest rapidly, and with as little soil contamination as possible. Hitting the correct moisture will help get an appropriate pack (density) and provide a better fermentation that produces high-quality forage for the best performance of your livestock.
December 14th, 2022
Author: Katie Raver
Gut Check
A healthy gut is the foundation of an environment that is better able to withstand the impacts of minor to moderate pathogen or toxin issues. However, if the gut becomes compromised feed hygiene issues can arise.. These issues can compound upon themselves, and often when we begin to see clinical illness on a farm, there is not just one culprit, but several contributing factors. Sub-acute rumen acidosis is a known issue of the foregut, however, more recently acidosis in the hindgut has become a frequent topic of discussion.
High starch levels coupled with poor starch ruminal starch digestibility may lead to increased starch fermentation post-ruminally which may have a negative impact on the gut’s protective mucosal barrier and epithelium. This damage may then create pathways for anti-nutritional factors to wreak havoc on the cow. When digestive upsets present themselves, we often find ourselves scrambling to find the root issue, however, monitoring key “risk factors” over time can help us understand challenges and act quickly to resolve them. This corn season presented many threats - varying by region. Some experienced a slow dry down leading to late harvest, intermittent drought, or persistent drought in some areas. Meanwhile, other regions saw a wet spring and others experienced late season moisture. With corn silage season wrapped up, we are finally starting to outline the potential risk factors this year’s crop brings to gut health.
Similar to the 2021 corn silage crop, in-situ starch digestibility in 2022 corn silage may be reduced as compared to previous years. Although fermentation can help combat some of these challenges, producers who are forced to open piles early may be at higher risk for increased starch passing into the small intestine or hindgut.
Figure 1. 7-hour in-situ starch digestibility over the past 4 years
| 2019 | 2020 | 2021 | 2022 | |
| Mean | 77.45% | 76.56% | 73.47% | 73.03% |
When evaluating potential feed hygiene challenges in 2023, two things stand out: increasing levels of Vomitoxin (DON) in corn silage and increasing enterobacteria levels in TMR.
Since September of 2022, 43 percent of corn silage samples tested have been above 1.5 ppm of vomitoxin (DON). Research conducted by Dr. Smith and colleagues at the University of Wisconsin has found that DON can be present in both ears and stalks of corn plants, and DON infection in the stalks may be especially hard to treat with fungicide application. That means, even if corn silage is treated with fungicide, it cannot arbitrarily be assumed to be DON-free. DON is often also used as a barometer for other potential contamination issues in the feed.
Figure 2. Vomitoxin levels across the US
Although, on average, DON is just approaching a concerning level, due to the high percentage of tests coming back with elevated DON concentration, I recommend keeping an eye on this as time progresses. Research has shown that DON levels can increase after ensiling, so although a crop may test low at one time point, this is not necessarily a static number and may necessitate further testing if issues arise. It’s also important to consider that this trend is not region specific, and we are seeing elevated levels in many different locations across the US (See Figure 3).
Figure 3. DON occurrence across the US
Although not specific to corn silage, there has been a slight increase in enterobacteria levels over the past year. Enterobacteria refer to a class of harmful bacteria that originate from the gut of animals. These include e. coli and salmonella, which can contribute to subclinical or clinical digestive upset alone, or in combination with other anti-nutritional factors. They typically arise when feed has been contaminated with manure or dirt.
Figure 4. Enterobacteria levels across the US
Alone, none of these individual feed hygiene factors are overwhelmingly concerning, but combined they have the potential to create issues within the cow. Monitoring potential feed hygiene issues over time can help take the fear out of digestive upsets by keeping risk factors on the radar even when clinical issues are not present. Monitoring key parameters ahead of time also help ensure the gut is in good shape and better equipped to handle feed hygiene challenges that may arise.
October 20th, 2022
Author: John Goeser
Rearview mirror insights as we look to 2022 silage
The 2022 corn crop got in the ground late for much of the US, meaning harvest for silage was delayed relative to the prior few years. Case in point: the 2021 harvest for silage was wrapped by mid-September. Harvest for silage was just getting started at that same time in 2022. As the 2022 silage quality picture has yet to be clarified, it’s pertinent to reflect upon what was observed in the 2021 crop to set a clear focus toward analyzing the 2022 crop.
Corn silage quality is a function of carbohydrate content and digestibility, namely digestible fiber and starch. These fractions make up roughly 80 percent of the energetic value per ton. Both are influenced by seed genetics, growing conditions, agronomic practices, and harvest management. In 2021, harvest timing [as indicated by whole plant moisture] appeared similar relative to prior crop years, as seen in Figure 1. This may be interpreted as the crop was harvested at a similar stage relative to prior years. However, starch content, as see in Figure 2, was numerically greater for 2021. More grain and starch equates to less fiber and generally more energy value per ton - assuming the starch in the grain is digestible. This assumption did not hold true, however, and 2021 netted less digestible starch, as showcased in Figure 3. This fact proved problematic for dairy and beef diets and producers’ pocketbooks as nutritionists needed to increase the concentrate in the diet and feed costs to meet production goals.
Looking now toward the upcoming 2022 corn silage crop feeding, beyond fiber digestibility, pay attention to moisture, starch content, and rumen starch digestibility. This latter nutritional aspect may prove pivotal in defining the 2022 corn silage crop quality. Stay tuned - we’ll have more to come on this.
Figure 1: Corn silage dry matter for US corn silage samples analyzed by Rock River Laboratory, Inc. for crop years 2019 to 2021.
Figure 2: Corn silage starch for US corn silage samples analyzed by Rock River Laboratory, Inc. for crop years 2019 to 2021.
Figure 3: Corn silage in situ rumen starch digestibility (7h, percent of starch) for US corn silage samples analyzed by Rock River Laboratory, Inc. for crop years 2019 to 2021.
August 24th, 2022
Author: Cliff Ocker
How much does corn silage harvest moisture affect fiber digestibility?
As we begin our 2022 corn silage harvest, there are often a number of questions around management factors to help put up the best crop. Moisture at harvest has a great influence on quality. Harvesting corn silage at the ideal moisture for your storage structure sets up the packing/density of the crop for optimum fermentation - which helps keep feed clean with less chance of molds and yeast infiltration. Hitting the correct moisture at harvest also improves the starch digestibility of the crop, but does it influence fiber digestibility?
To answer this question, I took a peek at the numbers from the 2021 corn silage samples within the Rock River Laboratory database. I reviewed Total Tract NDF Digestibility (TTNDFD), which provides the best comparison for fiber digestibility, as it takes into account four different fiber digestibility values versus looking at just one measurement. Figure 1 below shows the TTNDFD values of all corn silage samples from the 2021 crop that had a dry matter of less than 38 percent in the western, Midwest, and eastern US, is. Figure 2, comparatively, showcases the same regions, but where corn silage samples had greater than 38 percent dry matter.
Figure 1: 2021 Corn Silage TTNDFD for Samples <38% Dry Matter
Figure 2: 2021 Corn Silage TTNDFD for Samples >38% Dry Matter
Note the two to four point difference in TTNDFD between the two graphs, for each region. As the crop matures, lignin tends to increase, which decreases fiber digestibility. As with any crop, as the plant pushes its fruit or seed, the plant nutrients are pushed into the fruit or seed, leaving fewer nutrients in the stalk. Keep in mind that every two to three point change in total ration TTNDFD is equivalent to a pound of milk in dairy diets.
Corn silage is a staple in many diets and a great energy source to help meet the energy requirements of dairy and beef cattle. Obviously, a higher fiber digestibility (TTNDFD) allows the animal to utilize more energy from this forage, maintaining better health and performance.
As corn silage harvest gets underway, keep a close eye on the whole plant moisture level to ensure that you are putting up the best crop possible for your herd. Rock River Laboratory can help by providing moisture/dry matter results from representative field samples sent to the lab, or by using on-farm tools. Contact us for more details.
July 15th, 2022 Insights
Author: Katie Raver
Are you keeping score?
Starch availability is coming up quite frequently this year. Unique environmental conditions created some challenges with starch digestibility, and although this may be out of our control, many corn silage management factors can help improve starch digestibility.
Kernel processing score (KPS) is a metric to describe the degree to which the grain portion in corn silage is broken up. This is presented as the percent of kernels passing through a 4.75 mm screen. Kernel processing is a critical step in helping the microbes in the rumen gain access, through the tough outer pericarp, into the digestible starch endosperm. This will help maximize potential energy available to the cow from the feed, and in turn help increase potential milk production. The Rock River Laboratory recommended goal for KPS is 76.1%.
Figure 1. KPS distribution in corn silage for 2018-2021 crop years
In terms of the 2021 crop year across the US, processing levels were the highest they have been in the past four years. The industry has defined optimum processing as a KPS greater than 70%. Using this metric, more than 50% of samples tested for the 2021 crop year exceeded this goal!
When breaking mean KPS down by region, samples from the western US have the highest KPS on average. Meanwhile, corn silage from the eastern and midwestern US is similar - averaging between 68 and 69% KPS over the past four years. Figure 1 highlights that the average KPS in the eastern and midwestern US is not quite hitting the industry goal, represented by the orange line. This emphasizes some potential room for improvement. The 85th percentile for the West, Midwest, and East are as follows: 80.72%, 78.71% and 77.95%, respectively - showing that the top 15% of samples tested are exceeding the Rock River Laboratory goal.
Figure 2. Mean KPS scores for Midwestern, Eastern, and Western US over the past 4 years
Although we cannot retroactively improve KPS, management planning for the upcoming harvest can help to increase the KPS for future crops. Routinely testing and observing as harvest is occurring will help ensure rollers are set to achieve the desired score. Roller clearance should be set between 2-3 mm to adequately process kernels while not wasting time and fuel. Visual tests in the field during harvest, such as quantifying how many unprocessed kernels are in one quart, can help to make changes quickly. Lab testing should also be performed to capture an accurate KPS and ensure goals are being met.