Transition & Metabolic Health
Cows & Buffaloes
Grass Tetany — The Spring Grazing Danger of Lush Pastures
Updated 26 Aug 2026 • By Falah Nutrition Desk, Animal Nutrition Advisor
When animals move onto fast-growing spring grass after a long dry winter, a hidden mineral trap opens: lush young pasture can run critically low in magnesium. Milking cows drained daily by the pail are most exposed, and severe cases strike with frightening speed.
Common Signs
- Nervous, twitchy behaviour on new spring grazing — flicking ears, staring, easily startled
- Stiff, stilted walk progressing to staggering
- Muscle trembling, especially face and shoulders
- Sudden collapse with paddling limbs in severe cases — an emergency
- Milder ongoing form: irritable animals, reduced intake, sagging yield in the lush season
Possible Causes
- Rapid spring growth low in magnesium and fibre
- High-yielding milkers losing magnesium daily in milk with tiny body reserves
- Sudden full-time turnout onto lush pasture after winter stall-feeding
- Cold, wet spells on lush grazing worsening the imbalance
- Little dry fodder alongside — nothing slowing the watery grass through the gut
What the Farmer Should Check
- Has grazing shifted suddenly to lush young growth?
- Are the affected animals the heavy milkers — the classic victims?
- Is any dry fodder being fed before or alongside turnout?
- Is a mineral mixture with magnesium being fed daily through spring?
- Any twitchiness or stiffness in the herd since the grazing change?
Feed Guidance
Make the spring transition boring and mineral-backed: dry fodder into animals before turnout so lush grass lands on a working rumen, grazing hours increased gradually over a couple of weeks, and daily mineral mixture continued without a break through the flush — spring is the season it earns its keep most. Keep concentrate feeding steady for milkers (it carries minerals and slows the all-grass surge), and watch the heaviest milkers closest, especially in cold wet spells on new pasture. Where tetany has ever occurred locally, ask your veterinary doctor about magnesium-fortified supplementation for the risk weeks.
Relevant GOKA Products
Dairy Cows & Buffaloes
15-22 liters/day
Peak milk with high FAT & SNF
Dairy Cows & Buffaloes
10-15 liters/day
Maintains milk fat, prevents repeat breeding
When to Contact a Veterinary Doctor
A staggering, trembling or collapsed animal on spring grazing is a true emergency — call your veterinary doctor immediately; injectable treatment works, but only in time.
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