April Snow Showers Bring Stress and Scours

This spring we have had some very untimely snow storms.  Some have even been historical, such as the blizzard that hit most of the midwest including Minneapolis as I was traveling to the Montana Nutrition Conference and Livestock Forum.  Unfortunately, I was not able to attend the conference as my airplane was diverted and the rebooked flights canceled, TWICE! So now here I am some how stuck over a thousand miles from my destination (Bozeman, MT) in the upper penensula of Michigan.  However, this was a minor inconvenience for me compared with the obstacles cattle producers face this season.  Through social media I have read countless stories about ranchers doing all they could to save calves and help cows in these snowy, windy, unseasonably cold conditions.  I have read about ranchers who were out rounding up newborn calves that were struggling as the storm began to roll in.  Some of those producers wrote of feelings of sadness and failure as they lost visibility and it became unsafe for them to be out in their pastures attending to their livestock. Other farmers, were able to get their calves in a hoop house shelter or barn to ride out the storm.

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Joeseph Skroch’s calves in a barn riding out the blizzard in central Minnesota.

While the storm has past, producers are not in the clear just yet.  Weather events such as this blizzard put extra stress on cattle.  The increased levels of cortisol in the animal’s system suppresses the immune system leaving them more susceptible to other infectious agents.

In mature cattle, the suppressed immune system is often taken advantage of by infectious agents resulting in a respiratory disease.  Bovine Respiratory Disease Complex (BRDC) can be caused by viral infectious agents (Bovine Respiratory Syncytial Virus (BRSV), Parainfluenza 3 (PI3), Infectious Bovine Rhinotracheitis (IBR)), bacterial agents (Pasteurella multocida, Mannheimia haemolytica, Histophilus somni, Mycoplasma bovis) or a combination of any of the above.  

In calves, this increased level of stress and suppressed immune system culminates as diarrhea, or calf scours.  With the storm, chances of calf scours increases if the dam is shortchanged nutritionally resulting in poor quality milk for the calf.   If the dam is low on protien and energy, she cannot produce milk containing the nessicary antibodies to protect the calf.  Therefore, especially after this storm event it is important to ensure a well formulated diet for the cow.  Opportunistic infectious agents can also play a role in calf scours and can be bacterial (Escherichia coli, Salmonella, Clostridia perfringens), viral (Rotavirus, Coronavirus, Bovine Viral Diarrhea (BVD), IBR) or parasitic (Cryptosporidium, Coccidia).

When cattle are already under extra stress due to the weather, it is important to not add any additional stress through poor nutrition.  Be sure to formulate precise and accurate diets for both the cow and calf through feed testing and consulting at Ward Laboratories Inc.  A good ration to avoid nutritional stress will provide ample protein, and energy to meet physiological requirements of the animal.  It is also important to provide minerals in the diet to support the immune system. When the immune system is supressed from stress due to the changing weather, absorption of minerals vital to immune function such as magnesium, selenium, copper and zinc are supressed.  A combination of stress and imporper nutirition can render a good vaccine schedule useless.  In addition to providing a high quality diet, avoid feeding questionable feeds containing mold or aflatoxin as these agents may not directly cause illness or death, they can contribute to the suppression of the immune system resulting in respiratory symptoms and reduced reproductive productivity.  While no one can truly be prepared for all adverse weather events.  Producers can always utilize all their knowledge and resources to move forward after an event such as this spring’s blizzard and snowstorms.  Now hopefully I will have made it back to Kearney, NE by the time you are reading this post and we are done with all of this cold weather and on to summer forage production!

 

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.