North Dakota State University Extension Service - Burke County
Burke County AgAlert
May 8, 2008
Watch for Grass Tetany This Spring
Grass tetany is more likely in pastures with little litter or standing
forage from last year, according to Greg Lardy, North Dakota State
University Extension Service beef cattle specialist and professor in the
NDSU Animal Sciences Department.
Early grass growth often contains low levels of magnesium. When cattle or
other livestock consume these forages, they can develop a condition called
grass tetany, or hypomagnesia. As the term implies, cattle with this
condition have low blood levels of magnesium.
The most common symptoms associated with magnesium deficiency are excessive
urination, muscle spasms and staggering, as well as erratic and nervous
behavior.
The
onset of symptoms usually is quite rapid and affected animals simply may be
found dead in the pasture. Cows in early lactation may be more severely
affected since the demands of lactation further contribute to mineral
imbalances, Lardy says.
Cool-season grasses, such as crested wheatgrass or bromegrass, and annual
forages, such as ryegrass or wheat, often have been associated with grass
tetany. They generally have high protein and potassium levels, which can
worsen the problem, and low levels of magnesium. In some cases, native
pastures with limited amounts of litter also can result in grass tetany
cases.
“If grass tetany is a common problem in your herd, consider increasing the
magnesium level two weeks prior to the spring turnout date by adding
magnesium oxide to the diet,” Lardy advises. “It is not particularly
palatable, however, and should be blended with more palatable feedstuffs to
encourage adequate consumption.”
Producers should offer their cattle commercial mineral mixes containing 10
percent to 15 percent magnesium when the animals are grazing lush forages.
“The good news is that problems with grass tetany generally diminish as
summer approaches and forages begin to mature,” Lardy says.
DRY, DUSTY CONDITIONS AND GLYPHOSATE
Dry, dusty conditions have become a concern with preplant and PRE
applications of glyphosate. The dry conditions could result in weeds being
more difficult to control. Glyphosate is susceptible to being tied-up in
dust. If this is a concern adding additional water at 2 to 4 gallons per
acre can help reduce the potential concern with dust.
If weeds are under moisture stress increasing the rate of glyphosate is
recommended. There are many herbicides that can be added to glyphosate to
help improve control of hard to control broadleaf weeds in a burndown
application. Aim can be added to glyphosate to improve kochia control prior
to the emergence of many crops. Affinity or 2, 4-D can be added to improve
winter annual and wild buckwheat control. Always consult the glyphosate
label in question for approved tank-mix options and for what crops they are
labeled on.
Algae Growth in Sprayer Nurse Tanks
I often get calls from producers who are having problems with algae growth
forming a scum in their water tanks which plugs screens and nozzles in their
sprayers. Most herbicide dealers either have or can get algaecides which can
be added to the water to prevent algae growth. Most algaecides, like K-Tea™,
Super Algaecide Plus®, or Strike Out®contain a form of liquid copper which
does not cause any
antagonism or protagonism problems with herbicides. Other algaecides
sometimes contain various types of chlorine compounds which should not cause
problems either at the very low rates of use necessary to prevent algae
growth. If your local Ag supplier does not carry an algaecide try a spa or
swimming pool dealer.
Dan Folske
Extension Agent/Burke County
Soil Conservation Technology Specialist
PO Box 280
Bowbells, North Dakota 58721
dan.folske@ndsu.edu
701-377-2927