Spring Turn Out and Grass Tetany Prevention

Cow calf producers are eager to turn cattle to pasture and get away from dry lot or hay feeding.  The transition to grass comes with some risk, especially for areas that had a cool, wet spring or utilized grazing of small grain crops.  Magnesium is an essential mineral, and the cow does not have a tissue reserve.  Using a magnesium supplement in the spring is critical to the health of the cow.

Magnesium is needed for nerve and muscle function as well as bone formation. Unlike calcium, there is not a bone reserve of magnesium which requires regular daily intake to meet the cow’s needs.   Grass tetany is due to low blood magnesium resulting in nervous behavior, twitching on the face muscles and unsteady movement.  Grass tetany progresses with increased excitability, poor coordination and eventual collapse and death.  Cattle will appear bloated and have scrap marks on the ground due to thrashing and attempting to stand.

Potassium level of the diet has a significant impact on magnesium absorption.  Spring grass is elevated in magnesium with bromegrass, fescue and small grain forages being extremely high in potassium. Magnesium is absorbed through the rumen wall and the absorption rate can be reduced due to high potassium levels in the diet.  Salt plays a crucial role in magnesium absorption, nerve function and magnesium metabolism.  Offering free choice salt is necessary during spring turn out.

The high protein of spring grass is also a contributing factor combined with low carbohydrate level in the grass.  The high protein of the grass will contribute to high ammonia levels in the rumen which inhibits magnesium absorption.  A low moisture molasses supplement like Nelson Tubs provides the needed magnesium and sugars to improve rumen and removal of the ammonia by improving rumen microbial function and microbial protein synthesis.

Magnesium is bitter and will not be readily consumed by cattle.  Salt is often used to mask the bitter taste and attract cattle to a free choice mineral.  It is common for high magnesium minerals to be formulated at 10 to 15% magnesium with a target intake of 4 oz per head per day.  It is common for actual intakes to be less than 4 oz/day.  Nelson Tubs uses dehydrated molasses in the tub manufacturing process.  Molasses has a sweet attractive taste which mask the bitterness of the magnesium.  This results in consistent, daily intake that is very predictable, which is essential in delivering magnesium to prevent grass tetany.

Nelson Tubs offers a Hi Mag Tub in the Nelson Tubs line and a Mag Boost Tub in the Cow Country Nutrition line.  These products should be fed prior to and during spring grazing to as an effective magnesium delivery system.  Free choice salt should also be provided.  Check out our website

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