Managing Lush Pastures: Preventing Grass Tetany & Supporting Cattle Performance

Lush Pastures, New Challenges.

This winter brought above-average rainfall across coastal New South Wales and parts of Northern Queensland. While this rainfall has transformed paddocks into lush green pastures, it also presents unique nutritional challenges for livestock. The high quality of the pasture directly affects feeding strategies, supplement use, and ultimately cattle health and performance.

In Australia, when the rain arrives, so does the grass. Farmers welcome the growth, but fresh, fast-growing pasture often contains an imbalanced nutrient profile. Without proper management, this can compromise animal health and productivity.

The Challenge: Grass Tetany

Rapidly growing pastures such as ryegrass can be low in magnesium. Furthermore, high potassium levels in these pastures can further reduce uptake of magnesium by the animal. In addition, their high moisture and low fibre content lead to rapid gut transit, limiting the time available for magnesium absorption and worsening the deficiency risk. Low magnesium levels in the body can lead to Grass Tetany affecting the animals' nervous system and reduced milk production and in severe cases death.

Common signs of grass tetany include:

Hyper-excitability
Muscle twitching
Staggering or stiff movements
Nervousness
Aggressiveness
Reduced milk production
Falling down, convulsions, and sudden death

Early recognition and prompt management are essential to minimise losses and protect animal health. In cases of grass tetany, ensuring adequate magnesium intake through daily supplementation is the most effective strategy to prevent and control the condition.

Why Supplementation Matters

Supplementing lush pasture with balanced nutrition provides multiple benefits:

Nutrient Imbalance in Pastures: Lush, fast-growing green pastures, common during high-risk periods like early spring, may contain an imbalance of nutrients. Providing a supplement containing magnesium will increase the uptake and absorption of magnesium, to meeting the animal’s requirements.
Deficiency Prevention: Providing nutrients to meet the animal’s requirements, will not only assist production, but also help maintain good health, fertility and well-being.
Increased Magnesium Demand: Lactating cows have higher requirements for magnesium due to the output of magnesium in milk. Animals under stress (e.g. due to calving or cold weather) will also have higher magnesium requirements to cope with the stress.

Pasture Management Insights

Allowing grass to grow before grazing increases available feed and improves nutritional value. Timing grazing correctly ensures pastures supply adequate nutrients while maintaining long-term productivity.

Choosing The Right Feed Solution

Milk Maker Premium Dairy Pellets/Meal – A supplement for lactating dairy cows and beef cows with calves grazing pasture, hay, or silage. Milk Maker Premium Dairy are important on lush pastures because even abundant grass can contain a imbalance of the essential nutrients required for optimal milk production and cow health. Supplementing with Milk Maker ensures cows receive consistent energy, protein, vitamins and minerals for optimal performance and fertility.
XLR8 Pellets – Formulated for growing beef or dairy calves (12 weeks and older, 100–350kg liveweight). XLR8 Pellets play an important role on lush pastures by providing consistent, balanced nutrition that young calves’ may struggle to obtain from high-quality forage alone. The feed provides essential energy, protein, vitamins and minerals to support rapid growth, and promote the development of a strong, healthy rumen setting calves up for long-term productivity.

Every farming operation is different. That’s why Riverina’s team of nutritionists are available to help tailor feeding programs to suit your herd’s specific needs.

Want expert advice? Submit Website Enquiry by clicking this link and one of our nutritionists will be in touch.

Two happy Riverina customers on an on-farm visit preparing for warmer months.

Return to Knowledge Base All Categories