Grass tetany, also known as grass staggers or hypomagnesemia, is a common metabolic disorder that affects ruminant animals such as cattle and sheep. It is primarily caused by a deficiency of magnesium in the animal's bloodstream, which can lead to severe health complications if not addressed promptly.
Understanding Grass Tetany
Causes and Risk Factors
Grass tetany typically occurs when there is an imbalance of minerals in the animal's diet, particularly a deficiency of magnesium. Factors that contribute to the development of grass tetany include:
- Low Magnesium Levels in Forage: Grazing on pastures with low magnesium content can lead to a lack of magnesium intake, making animals more susceptible to grass tetany.
- High Potassium and Nitrogen Levels: Pastures with excessive potassium and nitrogen can interfere with the absorption and utilization of magnesium in the animal's body.
- Rapid Grass Growth: During periods of rapid grass growth, magnesium availability in the plants decreases, further exacerbating the risk of grass tetany.
- Physiological Condition of the Animal: Sick and old or younger animals may be more susceptible to grass tetany due to compromised immunity.
Symptoms and Diagnosis
Identifying the symptoms of grass tetany is crucial for prompt treatment. Common signs include:
- Muscular Twitching: Animals affected by grass tetany may exhibit muscular twitching, particularly around the face, ears, and flanks.
- Staggering Gait: Infected animals may have an unsteady gait, struggle to maintain balance, and exhibit difficulty in moving.
- Nervousness and Agitation: Grass tetany can cause animals to become restless, agitated, and display signs of discomfort.
- Reduced Appetite: Affected animals may show a decreased interest in grazing or consuming feed.
- Convulsions and Collapse: In severe cases, grass tetany can progress to convulsions and even result in the animal collapsing.
If you suspect grass tetany in your livestock, it is vital to seek veterinary assistance for a proper diagnosis. Veterinarians often conduct blood tests to measure the magnesium levels in the animal's bloodstream and confirm the presence of grass tetany.
Resolving and Preventing Grass Tetany
Supplementation and Balanced Diet
One of the primary methods to resolve and prevent grass tetany is through magnesium supplementation and maintaining a balanced diet. This involves:
- Magnesium Supplementation: Providing magnesium supplements, such as mineral blocks or oral drenches, can help replenish the animal's magnesium levels. It is important to consult with a veterinarian to determine the appropriate dosage for your livestock.
- Balanced Forage: Ensuring that the animals have access to high-quality forage with adequate magnesium content is crucial. Regular soil testing and appropriate fertilization can help maintain optimal mineral levels in the pasture.
- Mineral Mixtures: Using mineral mixtures specifically designed for grass tetany prevention can be beneficial. These mixtures often contain a balanced combination of magnesium, calcium, and other essential minerals.
Pasture Management
Proper pasture management practices play a significant role in minimizing the risk of grass tetany. Consider the following strategies:
- Grazing Management: Implement rotational grazing practices to allow forage regrowth and reduce the intake of magnesium-deficient plants. This helps ensure a more balanced diet for the animals.
- Supplemental Feeding: Providing additional feed, such as magnesium-rich hay or silage, during periods when the risk of grass tetany is high, can help mitigate the deficiency. Cows need at least 2g/kg DMI per day.
- Timing of Grazing: Avoid grazing animals on fresh/ early season pastures that are still deficient of magnesium.
- Apply Magnesium to Pasture: Apply magnesium oxide to the pasture at the rate of 30kg/ha every 21 days during the risk period. You can also spray pasture with magnesium sulphate every 2 weeks (2% magnesium sulphate in 1000L per hectare = 20kg/h).
- Long-term Remedy: Apply dolomite (contains some magnesium) or lime to correct the acidity of the soil. Plant clover crops and apply phosphate fertilizers. You should also limit application of nitrogen and potash fertilizers until the soil acidity is corrected or the clovers established.
Monitoring and Regular Veterinary Care
To effectively manage and prevent grass tetany, it is essential to monitor the condition of your livestock and maintain regular veterinary care. Consider the following:
- Health Checks: Regularly assess the overall health and condition of your animals. Promptly identify any signs of grass tetany and seek veterinary assistance when necessary.
- Vaccinations and Deworming: Follow recommended vaccination schedules and deworming protocols to minimize additional stressors on the animals' immune systems.
- Record Keeping: Maintain accurate records of your livestock's health, diet, and mineral supplementation. This helps track their progress and enables better management strategies.
By ensuring adequate magnesium supplementation, maintaining a balanced diet, implementing pasture management strategies, and seeking regular veterinary care, you can minimize the risk of grass tetany and promote the overall health and well-being of your animals.
