Estimations suggest that 1% of cattle in the UK will experience clinical grass staggers, with up to 30% of all clinical cases resulting in death and significant direct losses. A far larger percentage of animals, including ewes, will experience sub-clinical cases that may affect overall animal performance.
Grass staggers, otherwise known as grass tetany or hypomagnesaemia, is a very real threat for suckler and dairy cows at turnout as well as ewes post-lambing. However, it is easily managed by assessing and managing the on-farm risks and farmers are urged to consider options early this year, as a result of the extreme winter weather the UK has seen and the expected rapid flush in grass growth as temperatures begin to increase.
Grass staggers is defined as a deficiency of available dietary magnesium. Magnesium is a key macro-nutrient in the diet and is essential for bone growth and maintenance, nervous system function and also as an aid to fibre digestion in the rumen.
Rapidly growing spring grass typically has a low magnesium content (0.1 to 0.2% in dry matter) which, combined with its low dry matter and rapid transit through the rumen, can result in very low levels of magnesium absorption into the animal’s bloodstream. Magnesium is predominantly stored in the bones of the animal and consequently is not readily available when dietary supply is compromised. Stock therefore rely on daily magnesium supplementation to maintain adequate blood magnesium levels at times where risk is increased such as spring, and autumn.
In addition to the low magnesium content of spring grass, a number of other dietary factors can compromise magnesium absorption in ruminants, further elevating the problem of grass staggers:
To help alleviate the risk of grass staggers long fibre should always be available in the form of hay or silage, to help slow the transition of wet spring grass through the rumen. It is also essential to maintain dietary energy levels (notably starch and sugar) to help prevent excess rumen ammonia, dry matter intake, an adequate supply of minerals, trace elements and vitamins, and to also ensure a suitable supplementary sodium (salt) source is available to readdress the sodium to potassium ratio. Finally, and most importantly, it is vital to ensure stock have daily access to a suitable magnesium supplement.
Magnesium is typically an unpalatable mineral, so by presenting it in a molassed free-access lick, farmers can be assured that their stock has a reliable supplement to complement their diet. Ideally, magnesium supplements should be offered up to two weeks pre-turnout to better prepare stock for changes. Then, by turnout, they are familiar with the supplements and are not faced with a deficit.
Grass staggers is a common, well-known challenge at turnout that can be fatal, however, it’s easily avoided by predicting where the main risks are and addressing them with suitable magnesium supplements.
DOWNLOAD the NWF Feed & Mineral Bucket Leaflet.
For a quotation contact your local NWF feed specialist or call us on 0800 756 2787 or email us at sales@nwfagriculture.co.uk
Whatever your farming system we provide expert advice and solutions to help farm businesses
Improving Feed Efficiency with NWF Protected Feeds
24th February 2026
For modern dairy farmers, performance and profitability depend on one crucial factor: feed efficiency. With volatile milk prices, unpredictable weather and increasing pressure to improve sustainability, getting the most from every tonne of feed has never mattered more.
Read MoreHow Grassland Management and Creep Feeding Boosted Lamb Growth
19th February 2026
For over 40 years, Grove Farm in Somerset has been home to the Gammon family’s beef and sheep enterprise. Run by Alan, his wife Tracey and his daughter Jess, Grove Farm is home to 130 head of store cattle and 250 Texel Mules, along with Jess’s 60 Dutch Spotted ewes. Alan chose to base the sheep side of the operation on Texels because of the breed’s versatility, with excellent growth rates, body conformation, high killing-out percentages and carcass quality.
Read More5th February 2026
Early life nutrition sets the foundation for a lamb’s entire lifetime performance. In those first days and weeks, growth is rapid, immunity is still in development, and the metabolic systems are finding their rhythm. Providing the right nutrients in the right form gives lambs the best chance of thriving – and energised lamb milk plays an important role in achieving that.
Read MoreContact Us
Contact Enquiries on: 0800 756 2787
for Orders: sales@nwfagriculture.co.uk
or call: 0800 262 397
Friday 14th & Saturday 15th March 2026
Borderway, Carlisle, Cumbria, CA1 2RS
Visit the NWF trade stand and meet the team at UK Dairy Expo 2026. The NWF Sales Team will be offering information and advice on dairy compounds, blends and associated products.
https://borderwaydairyexpo.uk/Thursday 4th June – Saturday 6th June 2026
Royal Cornwall Showground, Whitecross, PL27 7JE
Visit the NWF trade stand and meet the team at the Royal Cornwall Show 2026. The NWF Sales Team will be offering information and advice on dairy, beef & sheep compounds, blends and associated products.
Wednesday 29th July 2026
Reaseheath College, Nantwich, Cheshire, CW5 6DF
Visit the NWF trade stand and meet the team at Nantwich Show for information on our dairy, beef and sheep feed range and associated products.
https://www.nantwichshow.orgAgriScot 2025
Borderway Agri Expo
Brailsford Ploughing Match 2025
The Dairy Show 2025
Contact Us
Contact Enquiries on: 0800 756 2787
for Orders: sales@nwfagriculture.co.uk
or call: 0800 262 397
Contact Us
Contact Enquiries on: 0800 756 2787
for Orders: sales@nwfagriculture.co.uk
or call: 0800 262 397
