Understanding Grass Tetany: A Springtime Risk
As spring pastures begin to green up, so does a serious but often overlooked danger—grass tetany, or hypomagnesemia. This metabolic disorder can affect a wide range of grazing livestock, including:
- Beef and dairy cattle (especially older, lactating cows)
- Sheep and ewes nursing lambs
- Goats, particularly during periods of rapid grass growth
These animals are most at risk when grazing on lush, rapidly growing pastures—typically in early spring or after a flush of regrowth in fall.
What Causes Grass Tetany?
Grass tetany is caused by low levels of magnesium (Mg) in the bloodstream. The most common scenario is:
- Grazing on lush, cool-season grasses like ryegrass, wheatgrass, or fescue, which tend to be naturally low in magnesium.
- Soils rich in potassium or nitrogen, which can inhibit magnesium absorption by the animal.
- High-producing or lactating animals, who have increased nutritional demands.
Symptoms to Watch For 🐄🐑🐐
Grass tetany can strike quickly and fatally. Watch for:
- Nervousness, twitching, or stiff gait
- Unusual aggression or excitability
- Muscle spasms or staggering
- Grinding teeth, bellowing, drooling
- Sudden collapse or convulsions
- In some cases, animals may be found dead with no warning signs
Prevention Tips ✅
Here’s how to protect all your grazing animals during risk periods:
1. Magnesium Supplementation
- Offer magnesium oxide in mineral blocks, loose minerals, or feed rations.
- Cows should receive 10–15 grams of magnesium per day; ewes and does need proportionally less, but still adequate levels.
2. Strategic Grazing
- Delay turnout on early spring pastures until grasses mature a bit.
- Mix in legumes like clover or alfalfa to boost pasture mineral balance.
3. Fertilizer Management
- Avoid heavy applications of potassium or nitrogen on grazing fields.
- Conduct regular soil and forage testing to monitor mineral content.
4. Animal Monitoring
- Keep a close eye on older females in peak lactation—these are your highest-risk animals.
- Consider magnesium supplementation, injections or boluses 30 days prior to turning out on pasture for highly vulnerable individuals.
Emergency Action Plan ⚠️
Suspect grass tetany? Take immediate steps:
- Call your veterinarian right away.
- Administer magnesium and calcium under veterinary supervision.
- Move the rest of the herd or flock off the high-risk pasture.
- Begin supplementation immediately to prevent additional cases.
Don’t Let It Catch You Off Guard
Grass tetany is fast, deadly, and often invisible—until it’s too late. But with a solid prevention plan and careful observation, your cows, sheep, and goats can thrive during spring pasture season.
Questions or need help setting up a mineral program?
Contact your livestock nutritionist, veterinarian or local extension office—they’re here to help!
Check out our High-Quality Vitamin, Mineral and Protein Supplements to help maximize your herds health. https://livestocknutritionsupplies.com/shop/
Stay informed, stay proactive, and together, let’s safeguard the well-being of our livestock.
Happy Spring!
Tyler Stehlik
Livestock Nutrition Supplies LLC
Info@LivestockNutritionSupplies.com
(531)333-3150
https://livestocknutritionsupplies.com/shop
For any questions or further information, please do not hesitate to contact us. We’re here to help you provide the best care for your animals.