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