Non-Protein Nitrogen and Soybeans: a Deadly Combination

Every once in awhile I get asked if soybean plants or stubble should be tested for nitrates.  Soybeans are legumes like alfalfa, and like alfalfa, under stressed conditions can accumulate a toxic concentration of nitrates.  Soybeans are listed as nitrate accumulators by the Iowa Beef Canter.  Therefore, if you are having doubts, send a sample to Ward Laboratories, Inc. for a test to make the best possible feeding decision.  Having received inquiries about nitrates in soybeans, I was reminded of a cow that got out into a soybean field and died of suspected nitrate poisoning last year.  However, when the soybean plants were tested, low nitrate concentrations were found.  Upon review of the animal’s diet history, non-protein nitrogen was consumed before the cow got out into the bean field.  Concluding that the more likely cause of death in the case of that specific cow was non-protein nitrogen poisoning.

Non-protein nitrogen poisoning occurs when the urea cycle is overloaded.  First, the ruminant animal consumes non-protein nitrogen typically in the form of urea in a supplemental feed.  If fed at high concentrations urea itself can be toxic.  Once in the rumen, urease produced by rumen microbes converts the urea to ammonia.  Ammonia is a form of nitrogen that microbes can use to produce amino acids and ultimately protein for their own population growth and production.  When too much ammonia is present in the rumen, it is absorbed through rumen epithelia and transported through the blood stream to the liver.  In the liver, ammonia is converted back to urea and transported to the kidneys for excretion.  When the kidneys are overloaded with urea and ammonia it continues to circulate around the body in the blood stream.  As a result, animals begin to have facial muscle spasms, frothy salivation, bloat or abdominal pain, labored breathing, frequent urination and weak staggered walking.  Often urea poisoning results in death.

UreaPoisioning

So, what does this have to do with a cow getting out in a bean field?  Soybeans produce the enzyme urease.  When a ruminant animal consumes urea in combination with raw soybeans, the concentration of enzyme is no longer a limiting factor in the rate that urea is converted to ammonia.  The rumen microbes can not keep up and the urea cycle becomes overloaded with ammonia and urea circulating in the blood stream even though the animal did not consume toxic levels of non-protein nitrogen.

This is one of the reasons why soybean meal is often sent to Ward Laboratories, Inc to check the activity level of the urease enzyme.  Soybean meal is processed and heated to high temperatures denaturing or melting the enzyme, thereby deactivating it.  So, if you plan to feed whole soybeans, which can be a great source of crude protein (approximately 40% crude protein on a dry basis) either ensure they have been heat treated or do not also feed a non-protein nitrogen supplement.  Additionally, do not feed a supplement containing urea when feeding a baled soybean stubble containing lots of leftover beans, ensiled soybeans or if cattle are grazing a cover crop mix which includes soybeans. Soybeans and urea rarely cross paths because both are used as protein sources, but when they do death losses are likely to occur.

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Prussic Acid and Nitrates in Sorghum and Sudan Grasses: Proper Sampling for Grazing Animals

Often, Ward Laboratories, Inc receives sorghum samples and producers want us to test prussic acid and nitrates.  My recommendation would be to send two separate samples when testing for grazing purposes because prussic acid and nitrates accumulate in different parts of the plant. Prussic acid accumulatesin the leaves of the grass in contrast to nitrate which accumulates in the plants lower stock.

Prussic acid is also known as hydrogen cyanide (HCN).  The compound is present in the leaves of the plants in a compound called dhurrin.  Under normal conditions, plant membranes separate dhurrin from the enzyme responsible for hydrolyzing HCN from dhurrin. Monogastric animals and hindgut fermenters such as swine and horses, typically do not have an issue with prussic acid poisoning as stomach acid deactivates the enzyme.  However, ruminants such as cattle, sheep and goats, are more susceptible to prussic acid poisoning due to the chewing of their cud.  As those animals ruminate, the cell membranes are damaged allowing the enzyme access to dhurrin, thereby releasing HCN into the rumen.  The HCN is then absorbed directly into the bloodstream where is binds hemoglobin.  The bound hemoglobin can not transfer oxygen to individual cells and death by asphyxiation is the result.

An additional risk for prussic acid poisioning is posed by stressed and damaged plants , this is when it becomes toxic to non-ruminant livestock.  Drought stressed plants may accumulate more unbound HCN in their leaves.  Frost damaged plants also have unbound HCN in their leaves due to the frost having broken the cell membranes allowing enzyme access to dhurrin.  In the case of frost, outer cell membranes have also been damaged, therefore waiting 4-5 days before grazing is sufficient assurance that the hydrogen cyanide gas has escaped the plant leaves.  After a frost, regrowth is toxic past the 4-5 day time frame and should certainly be tested before turning animals out to graze.

So, for testing prussic acid take leaves from 20 different plants across the field for a representative sample.  Do not cut the leaves and avoid as much damage as possible.  Immediately place all leaves in a gallon sized zip lock bag. Either ship the sample overnight, or drop the sample off at Ward Laboratories, Inc. as soon as possible.  When we receive your sample, we will refrigerate it and run it as quickly as we can as to not loose any HNC and to avoid a false low value.  Samples reported at >200 ppm as received are considered toxic and allowing animals to graze would result in a rapid death toll.

I have covered nitrate toxicity in other blogs including: Do I Need to Test for Nitrates?, 6 Cautions When Grazing Cover Crops, and 4 Considerations for Feeding Hail Damaged Forage and Crop Residues. So, for testing nitrates in sorghum and sudan grasses for grazing go into the field and cut the plant at the point where you plan to pull animals off.  Then, cut 4-6 inches above that, with this small piece use plant shears and snip it into pieces.  Repeat this with 20 randomly located plants across the field.  Then mix all the small plant pieces together and take a representative sub-sample from that pile.  Place them in a zip lock bag and send them to Ward Laboratories, Inc. for nitrate analysis.

In summary, test the leaves for prussic acid and the stocks for nitrate.  It is always important to take a representative sample for the most accurate results and informed production decisions.

Additional Resource:

Nitrate and Prussic Acid Toxicity in Forage

Do I Need to Test For Nitrates?

Last week I attended both the Colorado Cattlemen’s Annual Convention and the Sandhills Ranch Expo at the Ward Laboratories Inc tradeshow booths.  At both locations, producers had concerns about nitrates.  The climate and weather however were contrasting conditions.  Colorado producers wondered how drought stress might affect the nitrate levels in their forages, while Nebraska and South Dakota producers were concerned if too much precipitation might have affect nitrate levels in forages.  Here are 5 factors that affect how nitrates accumulate in forages.

  1. Plant Species

Some plant species accumulate nitrates more than others.  These species should be tested for nitrates regularly before feeding to animals.  These species are: sorghum (milo), sudan grass, millet, oats, johnson grass, broadleaf weeds, corn and sunflowers.  There are other species which also accumulate nitrates but not to the same extent as those listed above: wheat, rye, and triticale fall into these categories.  Finally, under extreme stress alfalfa and soybeans can accumulate nitrates, however the stress must be extensive, and this situation is very rare.

  1. Maturity of the Plant

Young plants and regrowth take up nitrogen from the soil faster than it can be converted to protein.  Older more mature plants take up nitrogen at a slower rate and have had plenty of time to convert nitrogen to protein.  Therefore, younger plants and regrowth tend to accumulate more nitrates than older mature plants.

  1. Plant Part

The lower 1/3 of the stock of the plant is where the most nitrates are stored.  Leaves and stems do not store nitrates in the plant. When grazing, leaving the last third of the stock might be a good idea to avoid any nitrate toxicity issues.

  1. Environmental Conditions

Stress due to weather or climate may increase nitrate accumulation.  During drought stress, the plant may be able to take up nitrogen but not have enough moisture to convert it to protein.  On the other hand, coming out of a drought a dramatic increase in moisture may cause the plant to take up more nitrogen than it can convert to protein in a timely fashion.  Frost and freezing temperatures also cause stress to the plant and nitrate accumulation.

  1. Management

Nitrogen fertilization is a common cause of nitrate accumulation in forages.  Nitrogen fertilization may increase yield, but it also increases risk of nitrate toxicities.

Nitrates are tricky.  I often run into producers who want to tell me their situation and management practices and ask if they need to test.  The truth is no one can determine the nitrate levels based on an antidote.  Testing is the only way to have full confidence.  If there are concerns, send forage samples to Ward Laboratories, Inc for a nitrates test and use the table below as a guide to interpert your report.

Nitrates

Test Forage Make More Money!

Soon we will be entering forage grazing and harvesting season. Although many producers test their hay or silages when buying and selling, there is still a group who either only test for nitrate when they believe they may be having an issue or do not bother to test at all.  There are many benefits to testing feed, such as improving animal health and production, but a major benefit from a business perspective is the potential to improve profitability.  Testing forages can help producers improve their bottom line.

I have attended several conferences where Dr. Aaron Berger from University of Nebraska Lincoln has spoken about profitability and costs to ranches.  The first point Dr. Berger always drives home is the unit cost of production.  It is important to keep track of all input costs to each enterprise on an operation to know what is profitable and what is losing money.  It is also a helpful tool to see where improvements can be made.  In his presentations, Dr. Berger also points out that the number one cost to produce beef cattle is feed.  Therefore, improvement in feed cost would increase profitability.  This can be done through selecting for cattle that consume less feed and gain the same, sourcing cheaper feed, and precise ration and diet formulations.

Precise ration and diet formulations improve profitability by reducing the occurrence of over or under supplementation to reach animal production goals.  To produce a precise and accurate ration or diet, forage testing must be done, otherwise producers are just guessing about the nutrient content of the forage.  Forages are variable plant material.  As the feed and NIR reviewer at Ward Laboratories Inc., I have seen alfalfa hays and grasses vary from a crude protein level of about 15% to 25% and 4% to 18% on a dry basis respectively.  The fiber content of various forages is also variable.  Acid detergent fiber (ADF) is used to calculate the total digestible nutrients (TDN) of the feed, so variation in ADF affects energy supplementation.  Neutral detergent fiber (NDF) affects how much of a forage or hay the animal will consume.  Minerals are also variable in forages and obtaining an idea of the mineral content may also affect mineral supplementation strategies, such as which mineral to feed or possibly creating a custom mineral mix.  If you would like to learn more about forage variability read Quarrels About Quality: 14 Sources of Variation in Forage and Hay Testing.

Testing hay and forage to formulate rations and diets can reduce underfeeding and overfeeding of animals.  When a producer overestimates the nutritional value of his forage, it can negatively affect the animal’s health.  Thereby impacting performance, reducing reproduction rates, decreasing lactation, or growth.  While the feed cost of an overestimated diet is lower, not meeting the nutritional requirements of that animal results in reduced performance and impacts the producer’s profitability.  An oversetimated nutitional value mresults in less protift. When a producer underestimates the nutritional value of a feed, overfeeding the animals results in increased feed costs and decreased profitability.  Additionally, if overfeeding is extreme, cows can become obese, which also can negatively impact reproductive performance.   In the case of underestimating a forage’s nutritional value, the cost of a NIR forage test ($15) at Ward Laboratories, Inc. is quickly made up in feed costs in just a few days of feeding.

 

So, to improve profitability, at a minimum forage testing is a necessity.  If cattle are grazing a pasture, crop residue, or cover crops, there is variation and a simple NIR test can provide information to make an informed supplementation strategy.  If cattle are consuming a total mixed ration, I would advocate to test all ingredients for the most profitable feeding ration possible with those ingredients.  Using feed testing to make decisions can increase an operations profitability through meeting animal nutrient requirements and therefore performance goals, as well as not wasting feed and money overfeeding animals.

Here are some other resources if you are still doubting the merit in hay testing for profit:

Test, Don’t Guess

The Importance of Forage Testing

Profit Tip: Understanding a Forage Analysis

There’s Money in Testing Your Stalks and Hay

A $50 Hay Test Can Save Producers Money

Forage Creativity: Soy-Corn Silage

Here at Ward Laboratories Inc., we often encourage producers to be creative and try newapproaches to agricultural production.  A couple of weeks ago at the American Society of Animal Science Midwest meeting in Omaha, I listened to a talk about getting more creative with corn silage: “Production of High-Quality Forage through Unique Forage Blends” presented by Dr. Ishwary Acharya.  Ward Laboratories Inc. tested 1,451 corn silage samples and 2,197 total silage samples of all types in 2016.  So, I have seen the range and variation in the nutrient quality of silages used in the area.  Dr. Acharya’s research focused on making the best possible silage for a dairy operation, as he stated in his talk, “the ultimate measure of forage quality is milk production”.  Being in central Nebraska, I think his research could not only increase the nutritional content of the silages produced, but also the value of grazing the cornstalks by a beef enterprise after harvest.

The idea behind Dr. Acharya’s presentation was to double crop corn and vining soybeans to produce high protein low fiber silage without sacrificing yield.  First, to produce the best possible corn silage, the crop was chopped higher than producers typically chop corn silage.  This resulted in less stock and more leaves, husks, and cob in the silage.  Therefore, yield was compromised for higher protein and lower fiber concentrations.  The second part of the presentation explained that to overcome the sacrifice of yield, vining soybeans could be intercropped with the corn.  Therefore, when chopping for silage at a higher level, the soybean plant material made up for the loss of stocks in the yield.  In this study, the resulting silage had increase yield, forage quality, and protein compared with typical corn silage.  Dr. Acharya interseeded the vining soybean at various rates and determined that the optimal rate was somewhere between 67% corn 33% soybeans and a 50:50 mix.  The study also looked at the optimal time for fermentation based on pH and presence of volatile compounds that have affect on rumen function and animal performance.  At 60 days of fermentation Dr. Acharya determined that fermentation had not gone to completion and the silage should be ensiled for at least a 90-day period.  This finding agrees with other literature I have read on the topic.

Dr. Acharya’s idea of double cropping to create a high-quality forage source for dairy cattle could also be of benefit to beef cow calf pairs grazing the remaining corn stalks.  If soybeans were intercropped, I would predict that there would be some beans and vining materials left in the field which would be higher in protein and lower in fiber than the corn stalks alone.  Of course, I would advocate that producers test both their silage and try to get a representative idea of what has been left on their field to provide necessary supplementation.  For the silage, I would recommend testing crude protein, acid detergent fiber to predict energy values and neutral detergent fiber to predict dry matter intakes at a minimum noting that the sample would need to be ran as a wet chemistry feed test and that the addition of soybean to the silage would not allow for a reliable and accurate NIR scan.  For the grazing stocks and soybeans, I would run the same test to get an idea if protein or energy supplementation are necessary.  I would also caution that soybeans do contain urease and we typically do not graze cattle on soybeans fields as they risk urease toxicity if they have recently consumed non-protein nitrogen (NPN), therefore when considering supplementation strategies for cattle grazing a field of cornstalks intercropped with vining soybeans, lick tubs or mineral mixes with urea could not be utilized.

As, with any novel feed, always monitor animal body condition, production and health to ensure it is providing the nutrients required.  Don’t be afraid to try something new.  It might be of benefit to your operation weather it is vining soybean corn silage or grazing cover crops or feeding from the waste stream, feed testing and good ration and diet formulation can lead to success of a livestock operation.

Drought Planning: 4 Ways to Stockpile Forages

The state of Nebraska is in the center of the High Plains Region of the United States.  The states that make up this region are Nebraska, Kansas, Colorado, Wyoming, and the Dakotas.  I checked the current drought monitor and found that southern Nebraska and southern Wyoming are abnormally dry, and Kansas, Colorado and the Dakotas are experiencing various levels of drought.  The current outlook through April is promising for the Dakotas, but dry for the rest of the region.  Precipitation from the Canadian border is predicted to remove the drought from North and South Dakota. The Dakotas are projected to experience a normal spring season.  As for the rest of the region, southern Nebraska, southern Wyoming, Colorado and Kansas, drought is likely to persist through April 1st.  Soil moisture levels on April 1st will have a great impact on the availability of forages throughout the region during the summer months. When planning for drought conditions, which are likely to result in decreased forage production, especially on dry pastures and rangeland, most producers’ strategy is to decrease animal numbers and stockpile forages.  Here are four ways to stockpile forages for livestock during drought conditions:

  1. Buy Hay

Buying hay is the first thing that usually comes to mind when people think of stockpiling forages.  During a drought, it is likely that local hay may be of lower quality, therefore it is important to test the protein and energy values (I reccomend a minimum of an NIR scan or the F-3 test at Ward Laboratories, Inc.) before feeding to ensure the forage will meet the animals’ nutritional needs. Hay nutrient values may change during transportation, so if hay is being shipped from another region be sure to test after receiving the lot and before balancing a ration to feed livestock.  Having extra stockpiles of hay for drought or emergency feeding is never a bad thing, however buying hay during a drought can be expensive due to less availability, higher demand, and transport costs.  Therefore, it would be beneficial to maintain supplies of hay during periods of plentiful forage conditions. In other words, it is most economical to buy hay in excess when it is low in demand and forages are in good supply and save some back as emergency or drought feed.  If you are located in Nebraska and are looking to buy hay check out the Nebraska State Hay Hotline.

  1. Graze Crop Residues

If your operation is located near farmland, consider working with your neighbors to allow your livestock to graze their crop residues.  Cattle can graze preferentially to take advantage of high protein, low fiber portions of the plants left standing in the field.  If you reside in southern Nebraska or Kansas, corn or wheat residues are good alternative forages especially when fed with energy supplements.  When grazing crop residues, be cautious and remember to test for nitrates before letting animals out onto the filed.  This option for stockpiling forages is cost effective, however labor intensive and may require cooperation with neighbors.  If you live in Nebraska check out the crop residue exchange to find farmers willing to let you take advantage of this great forage source.

  1. Graze Cover Crops

Adding cover crops to your own cropping rotation can be another great way to stockpile forages.  Cover crops allow you to extend the grazing season into the fall.  Preferential grazing increases the animals nutritional plane and therefore performance may also increase.  If you are lucky enough to get some moisture after grazing, cover crops may produce regrowth and animals may be able to graze those areas again.  There are also many benefits to adding cover crops into a cropping rotation for the soil. For more information on that read guest author, Emily Shafto’s Cattle and Crops: Completing the Nutrient Cycle. Planting a diverse cover crop mixture can ensure that if one species in the mix fails others will thrive, diversity can prevent disaster. Cover crops are cost effective as a source of forage, especially in a drought.  They are however, more labor intensive and if they are high in nitrates, prussic acid or sulfur, they may detrimentally affect animal health and mortality.

  1. Rent Additional Grazing Lands

If you are not located in an area where cropping agriculture is prevalent, and you rely on rangelands to provide forage for the summer grazing months.  Renting additional grazing lands may not be very cost effective immediately, but in the long run it will take some of the pressure off the lands typically grazed and allow them to rest and rejuvenate to provide forage for the next grazing season.  Renting additional grazing lands may be a hit to the pocketbook during that drought season, but it will prevent over-grazing, which is a necessity when practicing good land stewardship.

 

Stockpiling forages, using one or more of the strategies above, can help prevent a disastrous drought situation.  Always monitor the precipitation and temperature conditions so that you can do your best planning for the future.  Always look for creative ways to fill gaps in feed availability.  A feed or NIR test from WARD Laboratories, INC can aid in decision making when it comes to feeding alternate forages. When buying hay, test nutritional values after shipment and before feeding for accurate results.  When grazing corn stalks, oat stubble or wheat stubble check for nitrates before letting animals out in the field.  And revisit my blog 6 Cautions When Grazing Cover Crops to ensure you are feeding a safe forage when grazing cover crops.  For more information on drought planning visit the National Drought Mitigation Center.

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Integrated Systems Agriculture: 4 Benefits of Grazing Cover Crops to Beef Producers

Intensive, specialized crop production has several widely agreed upon downfalls.  These specialized systems tend to have stationary yields with expensive pesticide and herbicide inputs all while profitability is widely dependent on a global market over which we have little control.  Dependence on these practices  leads to higher resistance among  insects  and weeds, reliance on fertilizers due to nutrient depletion  in the soil,  soil erosion and contamination of waterways due to run off, and improper soil management practices. Soil scientists and agronomists agree that the addition of cover crops to a cropping rotation can improve soil quality and health through decreased erosion, increased microbial activity, increased carbon sequestration, more soil aggregates, and increased conservation of moisture in the soil, all due to a more extensive rooting system and ground residue protecting the soil for more months out of the year.  The addition of livestock, most commonly beef cattle, to this rotational cropping system decreases the need for herbicides and fertilizers, as they help deplete the weed seed bank and their manure contains many nutrients vital to plant nutrition and soil health. Guest author, Emily Shafto, covered the benefits to the soil extensively in her blog Cattle and Crops: Completing the Nutrient Cycle.  Here are four benefits of grazing cover crops to cattle producers:

 

  1. Grazing cover crops extends the grazing season, leading to decreased costs of stored feeds.  Supplementation needs are also lessened due to the animal’s ability to preferentially graze to meet their nutritional needs. According to a study by Practical Farmers of Iowa, grazing cover crops can offset winter feed storage costs by up to $40,000. Of course, it is important to mention that labor costs increase, and grazing cover crops requires more intensive management of the land and cattle.  The cost may be offset by the reduced need to cut and bale excessive amounts of hay or corn silage. Feed should still be stored for emergency use, such as a failed cover crop or a stressed crop that has accumulated too much nitrate to graze.

 

  1. Grazing cover crops can improve cattle’s nutritional plane through preferential grazing.  Animals consuming a cover crop mix can choose plant parts such as leaves over stems which are higher in protein and non-fiber carbohydrates and lower in fiber.  Cattle can also choose less mature plants for the same nutritional reasons.  Therefore, by grazing a mix of annual crops, cattle can consume more protein and carbohydrates for performance than a balanced ration of roughages and grain supplements. Therefore, grazing cover crops can improve nutrition and eliminate the cost of ration balancing and mixing.

 

  1. By improving their nutritional plane, animal performance can increase when grazing cover crops.  Growing steers typically have increased feed intake when consuming cover crops as opposed to a mixed ration, which results in increased weight gains.  Heifers and cows on the higher plane of nutrition provided by cover crops can have increased reproductive performance.

 

  1. Grazing cover crops rotationally can have an added benefit of forage regrowth.  When animals graze a paddock for the first time, they open the top canopy and allow sunlight to reach shorter plants.  When the cattle are removed from that section, plant growth is stimulated and if allowed enough time, may recover sufficiently enough to allow the area to be grazed again.   Grazing regrowth is like bonus forage and can also contribute to decreased feed production and storage costs.

 

Integrating cropping systems with forage production and grazing benefits soil health, grazing livestock, and your pocketbook.  Grazing cover crops specifically benefits beef production by extending the grazing season, thereby saving on winter stored feed costs, improving the animals nutritional plane resulting in improved animal performance through increased intake and gains, and bonus regrowth can also be grazed, again saving on winter feed costs.  Don’t forget to take proper precautions before allowing cattle to graze cover crops. See my blog post: 6 Cautions When Grazing Cover Crops.