Spring Calving and Magnesium: 5 Risk Factors for Grass Tetany

As they say, “spring has sprung!” That means the birds are out chirping, summer is on its way, baby calves are on the ground and lush, green pastures ready for grazing.  While this does paint a picturesque image, cattlemen know there’s a danger in those beautiful, green spring grasslands: a nutritional disorder known as Grass Tetany, Grass Staggers or Hypomagnesaemia.  Grass Tetany is a deficiency of magnesium in a cow’s body that causes them to stagger, look alert and become easily excitable and often results in death.  Magnesium is a required mineral for beef cattle.  It is involved in many enzyme activations and therefore important biological processes.  Magnesium is particularly involved in nerve and muscle impulse transmissions. There are 5 risk factors for developing this deficiency:

  1. Age or Maturity of the Cows

Older cows that have produced 2 or more calves in prior calving seasons are more at risk to develop a magnesium deficiency during lactation.  As a beef cow moves from the gestational to the lactational physiological state, magnesium requirements increase from 0.12% to 0.2% of the dry matter intake.  Older cows have a more difficult time mobilizing stored magnesium from bone to meet these increased requirements.  In beef cattle 65-70% of the body’s magnesium is stored in the bone. While the diet may technically meet requirements, without mobilization of stored magnesium grass tetany can develop.  More mature cows have more difficulty with this biological process.

  1. Fertilization Protocol of the Pasture

In soils, the fertilization protocol can greatly affect the minerals available in the grasses grown on that pasture.  High levels of potassium, nitrogen and to a lesser extent phosphorous in the soil can interfere with a plant’s ability to absorb magnesium.  This creates a forage that is low in magnesium and high in potassium and nitrogen.  Therefore, it is recommended that pasture fertilization protocols be managed with the use of soil testing at Ward Laboratories Inc. to prevent over use of nitrogen, phosphorous, and potassium (NPK) fertilization.

  1. Manure Management on the Pasture

Similar to over fertilization of pasture ground, over accumulation of manure from previous grazing seasons can also result in decreased magnesium in the grasses produced. Manure is going to add nitrogen, organic acids, and long chained fatty acids to the soil, which will also decrease the absorption of magnesium by growing grasses.  Resting a pasture,that has a high manure load, can help alleviate this risk for the next grazing occurrence.

  1. Species of Grasses

Plants deficient in magnesium tend to be rapidly growing cool season grasses.  Some species commonly involved with magnesium deficiency are orchard grass, rye grass, timothy grass, fescue grass, crested wheatgrass, brome grass, and small grain producing varieties such as oats, barley or triticale.  To decrease the risk of developing Grass Tetany, it has been recommended that producers introduce legumes to the pasture at a rate greater than 30% since species, such as alfalfa, are not typically deficient in magnesium with the NRC average being 0.37% of dry matter.

  1. Forage Nutrients

Pasture grasses with dry matter mineral concentrations of less than 0.2% magnesium and greater than 3.0% potassium are known to cause Grass Tetany.  Just like in soil, excess potassium in the diet interferes with magnesium absorption and forces cows to rely on mobilization of stored magnesium for lactation.  You can send your forage samples to Ward Laboratories Inc. to test for mineral concentrations to determine if your forage matches that profile.  If so, feeding a high magnesium free choice mineral may be necessary.  Magnesium concentrations in those minerals typically range from 8-12%.  Magnesium Oxide is typically the compound added to the mineral mix and is unfortunately unpalatable and therefore, as a producer if you may need to get creative with how you are going to get that magnesium into those cows, for example mixing it in with a protein supplement if free choice mineral intake is low.

In conclusion, there are 5 risk factors for development of Grass Tetany: maturity of cows, fertilization protocol on pasture, manure on pasture, species of grasses and forage mineral concentrations.  Ward Laboratories Inc. can help you manage your pasture with soil testing and your forage with feed analysis.

 

 

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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Quarrels About Quality: 14 Sources of Variation in Forage and Hay Testing

When it comes to hay testing, producers commonly grumble about the variation in Relative Feed Value (RFV) and protein content, based on their observations and what the lab reported.

Producers often have these concerns, because the RFV determines the price of a forage and how much customers are willing to pay.  An underestimated RFV can result in decreased profit for forage producers.  A couple weeks ago, I attended the NIRS Consortium annual meeting where Rocky Lemus gave a very informative talk about the importance of proper sampling, which addressed the producer concerns I often hear.  Variation in forage test results can come from in the field, storage, sampling, and in the lab. Here are 14 common sources of variation within a forage sample:

 

  1. The leaf : stem ratio, forages with a higher leaf : stem ratio are typically higher in protein and RFV. This is because the leafy portion of the plant contains more protein than the stems. Additionally, the stems are a structural part of the plant containing higher amounts of fiber.  Acid detergent fiber (ADF) and neutral detergent fiber (NDF) are used to calculate RFV therefore, forages and hays with more leaves and less stems are lower in ADF and NDF and higher in RFV.

 

  1. The weed content of a forage can affect the RFV. Weeds are high fiber plants, so the more weeds contaminating the forage or hay the lower the RFV. Weeds also tend to be lower in protein, thereby also affecting the nutritional content of the forage.

 

  1. Baling conditions can also affect the RFV of a hay. If hay is baled under moist conditions or after having been rained on, the water-soluble sugars have been removed from and plant. The percent of ADF and NDF are increased due to the absence of sugars.  The result is a RFV and lower energy forage.

 

  1. Species of forage also affects RFV. This is not news to hay producers or livestock feeders.  It is well understood that legume forages such as alfalfa and clover are typically higher protein and higher RFV, than grasses.  This is a result of the leaf : stem ratios.

 

  1. The maturity of a plant can also affect the feed value. Older more mature plants are more fibrous, and they typically have a lower RFV than a lush growing forage.                     plant maturity

 

  1. Fertilization can result in higher protein in a forage and lower ADF and NDF. Fertilization management may help produce high quality forages. Be cautious to avoid creating a high nitrate forage by applying too much fertilizer.

 

  1. Proper storage of a baled hay is very important. Reduce ground contact as this will result in accumulation of moisture from the ground and a decreased RFV. Protect your baled hay from the elements to avoid losses of soluble sugars and protein.  Wind and rain alike can remove the leafy portion of the plant thereby decreasing protein and RFV.

 

  1. Division of forages into separate lots can affect the accuracy and representation of a forage sample. Lots should be defined by both species and field from which it was baled. For example:  If there are three fields two alfalfa and one grass, the lots need to be separated by not only species, but also field as one location may have a differing quality that the other based on management, precipitation differences, or topographical differences.  Therefore, I would send three separate hay samples to Ward Laboratories, INC. for NIR testing.

 

  1. Proper sampling procedure is very important. Using a hay probe is the key to ensuring a representative sample. Hay probes can accurately represent the leaf : stem ratio, whereas using a hand grab can result in the leafy portions falling through fingers and obtaining an overrepresentation of stems and a lower RFV.  Additionally, with a hand grab only one layer of the bale can be grabbed and to ensure a representative sample it is important to sample several inches inside the bale.  For more guidelines and to become a certified hay tester visit the National Forage Testing Association.

 

  1. The number of cores taken is another source of variation when testing. The recommendation is to combine 20 randomly selected cores. The difference between taking 20 cores and 10 cores can cause variation in crude protein by up to 5%, meaning taking only 10 cores could either over estimate nutrient values or under estimate them.

 

  1. It is very important to ensure proper treatment of samples in delivery. If the sample is hay, it is typically dry enough to not have cause for concern. If it is a fresh forage clipping, check the moisture, if it is very damp rotting can occur on its way to the lab in just a few days stuffed in a box with other samples or envelopes.  Of course, the portion of the plant that rots first is the leaves, so the RFV decreases when this happens on the way to the lab.

 

  1. Splitting in the lab can also affect RFV. Ward Laboratories, INC. uses the cone and quarter method on all forage samples that come in the lab. It is very important that when the lab splits the sample for the portion to be tested it represents the sub sample given to us.  Sometimes, it is requested to send the sample on to other labs, when this happens, the sample is split into two – three sub samples and the NIR scans are checked to ensure the sub samples nutritional values repeat.  This way we can keep some sample in our lab in case further testing is requested and it is a good way to check that our sub-sampling procedure is accurate.                                                                                                                                                                                                                                                      img_2506-e1517945202593.jpg

 

  1. Drying of the sample in the lab can result in heat damage to the sample therefore again decreasing RFV. Ward Laboratories, INC dries samples in an oven at 64°C before grinding, the typical dry matter after grinding is between 95-97% dry matter. Other labs use microwave ovens for faster drying time, however using a microwave does result in higher incidence of heat damage to samples.

 

  1. Grinding of the sample can also make a difference as to how it scans NIR. Ward Laboratories, Inc. grinds samples through a 1mm screen. More coarse grinding can cause inaccurate results on the NIR instrument.

 

When questioning results of a forage or hay sample, consider all the sources of variation that went into that sample. Sampling plants is tricky business as it is a variable material.  Always do your best to take a representative sample.  Call the lab if you have questions or concerns before taking your sample or interpreting your results.