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

Rain is a Tricky Thing

We’ve all heard the Luke Bryan song “Rain is a Good Thing”. While it may be a catchy lyric, lack of rain can cause livestock producers to suffer from drought and heat stress issues, while too much rain can leave farmers dealing with flood damage.  This year has been especially testing from those aspects.  The southwest is on fire.  Colorado, Utah, Arizona and New Mexico and areas of Texas, Kansas and Missouri are suffering from extreme drought and wildfires with surrounding areas battling through severe and moderate drought conditions.

DroughtMapJuly19
http://droughtmonitor.unl.edu/CurrentMap.aspx

In contrast, there have been 6 major flooding events due to excessive rain which have been declared disaster states this summer.  There is no denying drought is difficult to handle, but flooding can be just as destructive with obstacles of its own.

flood timeline

To summarize the timeline above:

  • May 30 – Tropical Storm Alberto’s heavy rainfall lead to flash flooding in 10 southeastern states.
  • June 18 – Heavy rainfall in a short period of time lead to flooding mostly affecting the Upper Peninsula of Michigan, and parts of northern Wisconsin and Minnesota.
  • June 20 – Heavy rainfall resulted in river levels rising and floods in northwest Iowa and southeastern South Dakota.
  • June 21 – Some areas of Texas received more than 10 inches of rain in a 48-hour period resulting in flooding.
  • July 3 – Torrential rains resulted in flooding in southern Minnesota.
  • July 17- Heavy rain resulted in flash flooding in Washington D.C. and Massachusetts.

Rain resulting in flooding has several destructive effects on agriculture.  First, damage to infrastructure such as roadways and powerlines.  Dirt and gravel roads may get washed away during a flood, which will limit a livestock producer from checking and accessing animals.  In the event of an evacuation often the animals are unfortunately left to fend for themselves.  It is a challenge to put those access points back in place to get any operation up and running after the flooding.  There will likely be damage to other assets as well such as outbuildings and machinery.

Second, the flood waters may carry sand and other debris with it.  This debris will settle on top of fields and may result in a barrier to the soil, creating a challenge when trying to plant crops or maintain a pasture.  Removing the debris and sand can be financially exhaustive and labor intensive.

Third, heavy rainfall producing floods will likely erode the soil and carry away valuable top soil.  The erosion itself, will leave gaps and divots in fields making the next planting season more difficult with new obstacles in fields.  The loss of top soil means the soil in the field will have less nutrients and likely will have lost aspects related to a healthy soil including structure and beneficial microorganism populations such as mycorrhizal fungi.  It will be important for crop producers and pasture managers to consult with soil health experts such as Lance Gunderson or Emily Shafto at Ward Laboratories Inc. to replenish nutrients and rebuild soil health after a flooding event.

Fourth, if there were standing crops or forages in a field during a significant rain and flood event, those crops and forages likely are damaged.  Powerful rains and hail can physically damage plants.  Therefore, if harvesting for grain or planning to feed these crops or forages mold and mycotoxins should be tested.  Additionally, corn, sorghum, oats, and other nitrate accumulating forages should be tested for nitrates due to the additional stress from flooding.

Finally, field operations may be hindered.  Planting, and harvesting of crops may be delayed due to wet sloppy fields.  If the areas affected produce hay, harvesting, drying and baling all present unique obstacles.

In conclusion, rain is not always a good thing.  Too little leaves us with droughts and too much results in devastating floods.  Always consider the obstacles of these disastrous events and make a plan before they happen to avoid panic when natural disasters occur.

More Resources:

Flood List

Farming After Flooding 

The Impact of Extreme Weather Events on Agriculture in the United States

iGrow Flood Resources

 

Never a Dull Moment

Here at Ward Laboratories Inc there is always something happening.  This past month and the coming months include construction projects and new lab equipment.  This past week, we also became a zoo, I kid of course.

In the lab we are adding new fume hoods and expanding for new stations and lab equipment.  Once the construction is finished, we will be adding new tests including, enzyme testing for soil health, soil water holding capacity, and selenium in feeds.  In the mean time however, the air conditioning units can’t keep up as we are missing parts of walls, and technicians are providing their usual accurate and precise results dispite being a little displaced in the lab.  The remodel is quite a process.

Now I jokingly stated we are now a zoo, and while that may not be true we have had many visits from all kinds of creatures, kitties, bunnies, and a tiny toad.

A Comment on Rain Damaged Hay

The other day while it was raining cats and dogs outside, a customer asked how that rain would affect his freshly cut alfalfa hay.  Unfortunately, rain after cutting and before bailing only decreases the nutritional value of the hay. As the freshly chopped forage lays in the field getting rained on, water soluble compounds leach out of the plant.  These compounds include some nitrogen, some fat, minerals, vitamins, and water-soluble carbohydrates. The loss of the water-soluble carbohydrates results in an increase in the fibrous carbohydrates and therefore a decrease in the energy provided by the forage.  For more on that check out my previous post Carbohydrates and Forage Quality.  The loss of vitamins and minerals may also increase the importance of feeding those nutrients as supplements.

In addition to a poorer quality resulting hay, rained on alfalfa can support more mold.  If the mold count is significant, between 2-3 million spores per gram, it can be a contributing factor in respiratory and reproductive illnesses in livestock.

Furthermore, it is important to allow the rain damaged hay to dry to at least 12% moisture before baling.  If baled too wet, heat damage can occur, further reducing the quality of hay and nutrient availability of the hay for feeding.

Best of luck this harvesting season!

For more information check out this publication by the Iowa Beef Center:

Rain Damaged Hay can be Costly for Farmers

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

Silage for Beef Cattle 2018 Conference

Last week I attended the Silage for Beef Cattle Conference in Mead, NE.  For those of you who put up corn silage, or provide advice for those who do I would highly recommend listening to the online uploads from this conference as well as looking over the proceedings. Here are 8 key concepts I took away from the conference:

  1. Processing is crucial.

Processing of the grain is very important to the digestibility and therefore, energy availability of the corn silage.  It is recommended that there should not be a single intact corn kernel in the final silage product.  To monitor this, separate the forage portion of the silage from the grain and then closely inspect the grain.  Adequate and consistent monitoring through the chopping process is key.

  1. Determining when to harvest is difficult and varies by operation.

As the plant matures fiber increases, kernel hardness increases thereby decreasing the digestibility of the forage and starch portions of the plant.  However, at a more immature stage less corn kernels are present, and the moisture of the plant is too high for ensiling.  Therefore, the recommendation was to harvest a week before or at black layer when the dry matter content of the green chop is between 33 – 38%.  However, the best practices may differ from operation to operation.

  1. Ensiling time is important.

As fermentation time increases, starch digestibility also increases.  For the fermentation to go to completion, it is recommended to ensile at least 90 days, but 120 days would be optimal.

  1. Packing is key to minimize shrink and prevent spoilage.

Delayed packing increases risk of yeast and mold spoilage.  It is also important to pack with enough weight and consistency.  Check out this packing density calculator from University of Wisconsin extension.

  1. Proper covering is also key to prevent shrink and spoilage.

O2 barrier plastics are the best option for covering, however polyethylene coverings are also an option with about a 5% difference in dry matter recovery.

  1. There are lots of ways ensiling can go wrong.

Silage contaminants can come from many different sources including soil, damages plants from hail or insects, manure, wildlife, rodents and birds.  These contaminants can include infectious microorganism such as salmonella, listeria, clostridia and toxin producing molds or undesirable fermentation by-products such as toxic amines or ammonia.

  1. Feeding spoiled corn silage at any inclusion rate is detrimental to rumen health.

Both dry matter intake and digestibility of neutral detergent fiber decrease when spoiled corn silage is included in the diet.  Additionally, when cannulated cattle were examined, the forage mat in the rumen was completely destroyed, again at any inclusion rate of spoiled corn silage.

  1. Producers can determine if they have aerobic deterioration of silage on farm.

At Ward Laboratories, Inc, I often suggest producers who are unsure of their silage to test both mold count and pH.  On farm producers can take the temperature of the center of the pile and other outer locations.  Moldy spots will be 20-30°F hotter, with up to 8 times the coliform forming units of mold than the core of the pile.

Again, this is a snapshot of the important information shared at the corn silage conference.  Check out the online uploads and consider sending your silage samples to Ward Laboratories Inc. to test for nutrient contents, pH, moisture and mold count.

Backyard Bird Feeders

Recently, here at Ward Laboratories, Inc., birds have been the topic of conversation.  We have had birds in nest over our doorways:

babydove
Eurasian Collared Dove

birds in nests in surrounding trees:

babyrobin
Robin

and even birds in the ceiling!

bird in ceiling
Starling in the Ceiling

Additionally, being located in Kearney, NE, we see our fair share of avid bird watchers who are drawn to the area to view over half a million Sandhill Cranes that stop here in the Platte River Valley to refuel along their spring migration.  So, with all this talk about birds, of course I thought I should share our testing of bird food.

If you supply bird food to your backyard feathered friends, you have probably noticed there is a guaranteed analysis provided on each bag.  Commercial bird feed formulations are required to set minimum crude protein, minimum crude fat and maximum crude fiber levels.  Here at Ward Laboratories, INC., we test bird feed so the manufacturer can  ensure they are meeting set standards for each seed type or mixed feed.

 

birdseed
Bird Seeds