44 research outputs found
Controlling Grass Tetany
Grass tetany is a nutritional
disease that occurs in beef and
dairy cattle and sometimes sheep.
Deficient levels of magnesium in
the diet cause the disease, which is
responsible for the deaths of many
cows in the United States and
other countries. Grass tetany is
sometimes called hypomagnesemic
tetany, lactation tetany, grass staggers,
or winter tetany.
Cows are particularly susceptible
to tetany when nursing a calf or
producing milk. Sometimes pregnant
animals die from the condition.
Older cows are more susceptible
than those with their first or
second calves. Also, cows that are
herded or worked may be more
susceptible to the disease
Shade-induced Grass-Tetany- Prone Chemical Changes in Agropyron desertorum and cinereus
Grass tetany, a magnesium (Mg) deficiency in grazing ruminants, often
occurs simultaneously with periods of reduced solar radiation levels. The objective of
this study was to determine if reduced radiation levels produce a chemical composition
in grass indicative of a tetany-prone forage. Two grass species were exposed to three
radiation levels (8, 25, and 100% of actual) by shading with burlap cloth. The vegetatively
growing forage was harvested at weekly intervals over a 5-week period during
early spring.
Shaded forage had higher concentrations of Mg than did unshaded forage. However,
shaded forage compared to forage grown in full sunlight would likely result in less Mg
being available to the animal. The hypothesized inverse relationship between radiation
and the incidence of grass tetany in Idaho, Nevada, and Utah is supported by field
observations
Forage Crops: Grass Tetany
Grass tetany is a magnesium (Mg)
deficiency in cattle and other ruminants that has
caused many livestock deaths in the United States
and throughout the world. The occurrence of grass
tetany depends greatly on forage constituents that
reduce the availability of dietary Mg. Recent research
findings are increasing our understanding
of this difficult nutritional problem
Magnesium Concentration in Agropyron desertorum Fertilized with Mg and N
Grass tetany, a Mg deficiency in ruminants, is responsible
for large economic losses throughout temperate regions.
Significant livestock losses occur in the semiarid
western United States primarily when livestock are grazing
the spring growth of Agropyron desertorum, an introduced
grass species which provides much needed early
spring forage.
The objective of this study was to increase forage Mg
to about 0.2% by Mg and N fertilization and thus meet
animal needs and reduce losses from death. The field
study was located on A. desertorum grassland which had
previously produced grass tetany. Two calcareous aridisols
were each fertilized with 0, 90, 200, and 600 kg Mg/
ha as MgSO?•7H?O, having split plots with 0 and 150
kg N/ha applied as NH?NO?. Forage was harvested at
regular periods intended to bracket the spring occurrence
of tetany for three seasons following fertilization.
Fertilization with 600 kg Mg/ha was necessary to increase
forage Mg to the recommended level (0.2%). Applying
150 kg N/ha increased forage Mg concentration
as much as did 200 kg Mg/ha. The N and Mg fertilizers
were additive in increasing forage Mg concentrations.
Forage Mg concentrations decreased with increasing age
of vegetatively growing grass, and the benefits from fertilization
were less with each successive season following
fertilization. Little residual effect of 600 kg Mg/ha or 150
kg N/ha fertilization on plant Mg concentration would be
expected after 5 years. Rapid decreases in water-soluble
soil Mg with the resulting formation of some unknown
insoluble phase, as well as high investment costs, preclude
Mg fertilization of these ranges to meet Mg requirements
of grazing animals
Controlling Grass Tetany
Grass tetany is a magnesium deficiency that occurs in
beef and dairy cattle and sometimes sheep. It has been
responsible for a large number of deaths of cows in the
United States as well as in other countries. It is sometimes
called hypomagnesemic tetany, lactation tetany,
grass staggers, wheat pasture poisoning, or winter tetany.
Cows are particularly susceptible when nursing a calf
or producing milk. Sometimes pregnant animals die from
the condition. Older cows are more susceptible than
those with their first or second calves. Also, cows that
are herded or worked may be more susceptible to
tetany
Soil-Climate-Plant Relationships in the Etiology of Grass Tetany (Chapter 6)
Hypomagnesemia is a metabolic disorder of ruminants not receiving
adequate utilizable magnesium, either because of low Mg concentration
in the forage or because of complicating factors affecting Mg availability.
The disorder is more likely to affect cattle than sheep or goats and generally
affects older, lactating animals. Magnesium deficiency may result in
decreased milk or beef production (Grunes & Mayland, 1975; Grunes et
al., 1970). An intensified hypomagnesemia, known as grass tetany, has
caused a large number of cattle deaths in the temperate regions of the
United States and other countries, resulting in losses of up to 3% in dairy
or beef herds in a bad year (Baker & Gould, 1976; Grunes et al., 1970;
Mansfield et al., 1975; Molloy, 1971). In some individual herds in some
years losses have been even higher. Reid et al. (1978a) estimated annual
losses in the United States at 1 to 2% of mature grazing animals. The
severity of the problem is quite sporadic.
Many factors affect Mg uptake by plants and its subsequent availability
to animals. It is our objective to discuss the soil, climate, and plant
factors that may ultimately affect Mg intake and availability to
ruminants
Composition of lipids of cereal forages as related to tetany in cattle
Forage samples were collected from mixed winter
wheat and rye (Triticum nestivum L. and Secale
cereale L.) pastures, from December through April
at El Keno, Oklahoma, while they were grazed by 32
mature cows to determine if the concentrations and
speciation of naturally occurring higher fatty acids
(HFA) in forage were related to the incidence of
tetany. Forage samples were analyzed for N, K,
aconitic acid, total lipids and total and individual
C11 to C18:3 HFA. Total HFA and lipid values were
high in the very immature forage, but these values
decreased as the winter season progressed. In early
March, these values increased sharply coinciding with
rapid forage growth and were near maximum on the day
(19 March) when tetany occurred in five cows. Forage
N concentrations were also maximum on that day and
then declined rapidly with time. A positive
correlation (P <.05) occurred between forage N, total
lipids, HFA, K, aconitic acid, and C18:3. A negative
correlation (P4.05) occurred between total
lipids and C18:2 and C16; HFA and C18:2, and between
C18:3 and C18:2 and C16. Aconitic acid and K were
also negatively correlated with C16 and C18:2.
Linolenic (C18:3) was the predominant fatty acid
(62 percent), followed by palmitic (C16 at 15 percent)
and linoleic (C18:2 at 10 percent). Other
fatty acids (C12, 14, 16:1, 18 and 18:1) constituted
the remaining 13 percent. The fatty acid composition
was similar to that reported in other gramineae
forages. It was concluded that the naturally
occurring HFA could be a factor in tetany of grazing animals
Seasonal Changes in Trans-aconitate and Mineral Composition of Crested Wheatgrass in Relation to Grass Tetany
Grass tetany (hypomagnesemia) frequently occurs from March through
June in cattle grazing crested wheatgrass in western United States. High levels of trans-aconitate
and/or citrate, K, K/(Ca + Mg) ratios and low Mg in the grass are implicated
in the etiology of the disease. In the moist 1967 season, during periods of "flush"
growth following warming trends, trans-aconitate and K increased while Ca and Mg
decreased in crested wheatgrass. These characteristics may explain the incidence of
grass tetany during periods of "flush" growth. During the dry 1968 season, these
trends were not observed. Growth chamber studies confirmed some of the reasons for
changes in crested wheatgrass composition observed in 1967 and 1968
Grass Tetany Hazard of Cereal Forages Based upon Chemical Composition
The occurrence of grass tetany in cattle grazing small
grains pastures led us to examine the forage chemical
composition and to suggest the relative risk of grass
tetany to cattle grazing each forage.
Early spring vegetative growth of wheat (Triticum
aestivum L.) and crested wheatgrass (Agropyron desertorum
(Fisch.) Schult) was periodically sampled from 3 x
20 m plots established on a fertile Portneuf silt loam
(Durixerollic calciorthid). In addition, wheat, oats
(Avena sativa L.), barley (Hordeum vulgare L.), and rye
(Secale cereale L.) were grown in pots containing Portneuf
silt loam in the greenhouse and were harvested once while
still vegetative.
Forage samples were freeze-dried and the following
parameters determined: total N (Kjeldahl); NO-? (electrode);
Na, K, Mg, and Ca (atomic absorption); S and
Cl (x-ray); P (vanadomolybdate); aconitic acid (polarography);
higher fatty acids and ash alkalinity (both by
titration). Estimated blood-serum Mg values were calculated
from a generally unavailable Dutch nomograph
of forage N x K and Mg values. The nomograph is
included in this paper to enhance its availability.
Wheat forage seemed to pose a greater tetany hazard
than the wheatgrass because wheat had lower values for
Ca and higher values for K, K/(Ca + Mg), aconitic acid,
ash alkalinity, and HCA. The estimated tetany hazard
of the cereal forages was wheat > oats = barley > rye.
This ranking corresponded to the other of blood-serum
Mg levels predicted from the Dutch nomograph. Wheat
forage was lowest in Mg, while rye forage was highest
in Mg and Ca, and lowest in K and N. Aconitic acid
represented a large portion of the total organic acids in
oats, rye, wheat, and wheatgrass, but only traces were
found in barley.
The frequent occurrence of grass tetany in cattle grazing
wheat forage may result because of lower Mg and Ca
levels and higher K, N, ash alkalinity, and HFA levels in
this forage compared to other cereal forages
Composition of Lipids of Cereal Forages as Related to Tetany in Cattle
Forage samples were collected from mixed winter
wheat and rye (Triticum aestivum L. and Secale
cereale L.) pastures, from December through April
at El Reno, Oklahoma, while they were grazed by 32
mature cows to determine if the concentrations and
speciation of naturally occurring higher fatty acids
(HFA) in forage were related to the incidence of
tetany. Forage samples were analyzed for N, K,
aconitic acid, total lipids and total and individual
Cll to C18:3 HFA. Total HFA and lipid values were
high in the very immature forage, but these values
decreased as the winter season progressed. In early
March, these values increased sharply coinciding with
rapid forage growth and were near maximum on the day
(19 March) when tetany occurred in five cows. Forage
N concentrations were also maximum on that day and
then declined rapidly with time. A positive
correlation (P<.05),occurred between forage N, total
lipids, HFA, K, aconitic acid, and C18:3. A negative
correlation (P<.05) occurred between total
lipids and C18:2 and C16; HFA and C18:2, and between
C18:3 and C18:2 and C16. Aconitic acid and K were
also negatively correlated with C16 and C18:2.
Linolenic (C18:3) was the predominant fatty acid
(62 percent), followed by palmitic (C16 at 15 percent)
and linoleic (C18:2 at 10 percent). Other
fatty acids (C12, 14, 16:1, 18 and 18:1) constituted
the remaining 13 percent. The fatty acid composition
was similar to that reported in other gramineae
forages. It was concluded that the naturally
occurring HFA could be a factor in tetany of
grazing animals