Grass tetany may be a problem this spring due to the excessive snowfall this winter and the recent spring rains. Grass tetany typically happens when cattle are grazing lush, green grass that is rapidly growing.
The cows suffer from magnesium (Mg) deficiencies as a result of the grass' quick growth and low magnesium content.
Low blood levels of magnesium are a symptom of grass tetany, a metabolic disorder. Because they might not be able to mobilize Mg from their bones as effectively as younger cows, older cows tend to be more vulnerable.
Due to the increased demand for Mg in the milk, cows in the early stages of lactation are most vulnerable to grass tetany.
In lush, green grass that is also rich in potassium and nitrogen, the risk of grass tetany rises. The rumen's ability to absorb magnesium can be hampered by both potassium and nitrogen.
Early lactation places a high demand on calcium as well, which when combined with a Mg deficiency could lead to more severe cases of grass tetany.
Cattle may go off feed for 1-2 days due to additional stress or bad weather, which may cause low Mg levels in the blood, which can cause grass tetany.
A higher water content in grasses during the early growing season will dilute the minerals and nutrients therein. Cows might not be able to consume enough grass to meet their needs on a dry matter basis.
As an illustration, a 1310-lb cow consuming 2.5% of her body weight in dry matter daily requires about 33 lbs of dry feed. She would need to eat 132 pounds of the lush, green grass in order to consume 33 pounds of dry matter if the grass is 75% water.
Table of Contents:
- Why are cows at risk of grass tetany in the spring?
- Grass Tetany - Causes
- Signs and Symptoms
- Treatment of affected cattle
- Prevention and Control
- Management ought to strive to
- Prompt actions
- Long-term measures
- Additional magnesium dietary supplement option
- Diseases similar to grass Tetany
- How a veterinarian can help
Why are cows at risk of grass tetany in the spring?
When beef animals have low magnesium (Mg) levels in their blood, grass tetany develops. Stumbling, convulsions, excitement, twitching, and death are among the symptoms. Although it can affect calves, older lactating cows are typically affected.
The diet's Mg requirement for a pregnant cow is 0.12% of dry matter and increases to 0.20% during lactation. Additionally, colostrum contains three times as much magnesium as the rest of the lactation's milk does. Therefore, early in lactation is when risk is highest.
Furthermore, Mg is not stored and mobilized in the tissues for times when it is lacking in the diet, unlike some other minerals.
The amount of magnesium that is absorbed across the rumen wall and circulates in the blood is directly related to how much was consumed.
Along with the fact that the Mg requirement rises during lactation, feeds high in potassium (K) or nitrogen (N), such as lush cool-season forages that grow quickly, can also reduce the absorption of Mg.
Therefore, more magnesium must be consumed to achieve the same blood levels of magnesium when cows are grazing lush cool-season pastures. Furthermore, the risk of grass tetany is frequently raised by cool, cloudy days that are related to wet springs.
Grass tetany - causes:
Cattle have stores of magnesium in their muscles and bones, but they are not easily accessible or usable when needed. Since the animal continuously loses magnesium through its urine, feces, and milk, it must be provided in its feed in order to meet daily needs.
A cow needs a consistent dose of magnesium during peak lactation (6–8 weeks after calving) to replenish the significant amount lost from the body through milk. The magnesium loss in milk doesn't change even when the magnesium content of the meal is low.
- Compared to legumes or weeds, cool season grasses and cereals have lower magnesium concentrations.
- In grasses grown in leached acid sandy soils, levels are low.
- Levels are low and growth is vigorous when potash and nitrogen fertilizers are used.
- Grass with a high moisture content has a quick gut transit and little uptake.
- Due to high rumen potassium and nitrogen levels and low rumen sodium, there is a reduced ability to absorb magnesium.
- Low caloric intake, fasting, or abrupt feed changes
- A bad climate, particularly winter storms
- Stress from yard work or transportation
- Low intake of roughage (young grasses have low roughage and frequently have a poor flavor)
- Low salt and phosphorus intake.
Signs and Symptoms:
Finding dead cows is typically a farmer's first indication of a grass tetany outbreak. The ground is typically rubbed while there is froth coming from the mouth and nose.where the animal's legs jerked wildly in front of her died. muscular spasms (tetany) and agitation are the most typical signs.
A cow may have abnormally low blood magnesium levels in the mildest form and not exhibit any symptoms. For days or even weeks, everything may go smoothly before she experiences stress from, say, yardwork, mustering, or trucking, at which point symptoms may appear.
Early indications of the condition include stiff gait, wary appearance, and twitching of the face and ears. These early warning signs are frequently ignored.
The cow is wild, her front legs "goosestep," she dislikes being driven, her tail is held a little high, and she might even appear to be blind in the intermediate form.
At this point, some people recover, but without treatment, the majority will deteriorate and pass away.
In the most severe case, excitement, galloping, bellowing, and stumbling are frequent symptoms. The cow quickly collapses on her side, her stiff, extended legs flailing back and forth (leg paddling).
She froths at the mouth and slightly arches her back. If the animal is lying down and has already been attacked, any disturbance (especially if she is touched) could trigger a fresh leg paddling attack. If the animal is driven or stressed in any way, she may pass away shortly after being seen stumbling.
Treatment of affected cattle:
Magnesium levels in the blood must be raised. The best outcomes are obtained when a calcium and magnesium solution is administered intravenously to animals.
Producers can inject a calcium and magnesium solution under the skin, though, in urgent situations where time is of the essence.
To avoid relapses, farmers should also give affected herds oral sources of magnesium. These consist of:
- Using magnesium oxide powder to sprinkle on pasture or hay
- Blocking magnesium lick
- Capsules with a slow release
- Magnesium can be added to concentrates or pellets by adding magnesium sulphate or soluble magnesium chloride to hay or silage.
Your veterinarian, a feed distributor, or a company that provides rural supplies all carry these products.
Prevention and Control:
Management ought to strive to:
- Eliminate elements that hinder the absorption of magnesium
- Give magnesium supplements.
Prompt actions:
- Increase your intake of energy and roughage. Silage and high-quality hay are appropriate.
- If introduced carefully and cattle are accustomed to them, pellets or grain can be added.
- If a natural source is unavailable, provide salt.
- Place lactating cows (especially older animals) in pastures with high levels of dry matter and legumes.
- provide protection
- Reduce the stressors (transport, yard work)
- Supplement with magnesium as described below.
Long-term measures:
- Using lime or dolomite (which contains some magnesium) to reduce soil acidity
- Grow clovers.
- Apply fertilizer with phosphate.
- Potassium and nitrogen applications should be kept to a minimum until soil acidity is reduced and clovers are established.
- Plant tree lines to provide cover.
- Maintain accurate records to guide future management.
- Consider pasture leaf analysis for magnesium and potassium for problematic paddocks. For additional advice, speak with your veterinarian.
Additional magnesium dietary supplement options:
Applying magnesium sulphate to hay rolls:
- For every kilogram of dry matter, lactating cows require at least two grams of magnesium.
- To help make up any shortfall, add 3g of magnesium sulphate for every kilogram of hay (a 350kg roll of hay requires 1kg of magnesium sulphate).
- To make it more palatable, add molasses. 20 liters of hot water should be used to dissolve 1 kg of molasses and 1 kg of magnesium sulfate. Spray this on after the hay has been rolled out or soak it into the hay roll before feeding.
- During risky times, sprinkle dry magnesium oxide on pasture at a rate of up to 30 kg/ha every three weeks (the magnesium content of magnesium oxide is the highest of all supplements).
Diseases similar to grass tetany:
Due to the similar symptoms of several serious diseases, a veterinarian's accurate diagnosis of grass tetany is crucial. These consist of:
- Staggers brought on by nitrate/nitrite poisoning, which also affects young, rapidly growing, heavily fertilized grasses and cereals, include those caused by phalaris, perennial rye, paspalum, and annual rye-grass.
- Lead poisoning, which is typically caused by discarded batteries, rare illnesses like bovine spongiform encephalopathy (BSE) and Aujeszky's disease, as well as locally endemic viruses and bacteria.
How a veterinarian can help:
A veterinarian can look into whether grass tetany or another illness is present. Producers should speak with their private veterinarian or the DPIRD veterinary officer in their area if they notice any unusual symptoms or grass tetany in their livestock.
As part of the National Transmissible Spongiform Encephalopathies Surveillance Program (NTSESP), the producer may be eligible to receive compensation from DPIRD if a veterinarian autopsies cattle between 30 months and nine years old that exhibit neurological signs (such as grass tetany signs).
Private veterinarians can also receive incentive payments through the NTSESP. The National Transmissible Spongiform Encephalopathies Surveillance Program website has more details.
These payments encourage the reporting of neurological symptoms so that Australia can demonstrate that enough animals have been tested and the results have been negative, demonstrating that we are free of illnesses like bovine spongiform encephalopathy (BSE). For Australia to keep its export markets, it needs this evidence of freedom.
Tags:
cattle health
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