While getting cows out on grass brings many management benefits, early spring grazing can also be the source of a significant health challenge in dairy cows. Lush, green, low mineral, early season grass is often lacking magnesium and when lactating cows are turned out onto this grass to graze, they risk developing hypomagnesaemia – also known as grass staggers. This is a serious metabolic disorder and can ultimately result in a cow’s death.
What is staggers?
“Staggers is triggered by low magnesium levels in the blood and usually occurs on cold and wet days, when grass intakes are suppressed,” explains Sue Cowell, ForFarmers Product Manager. “The lack of magnesium reserves in a cow’s skeletal structure makes hypomagnesaemia a very difficult condition for cows to try and control themselves."
“While the low mineral content of early season grass is the most common cause of grass staggers, it can also be brought on by underfeeding, low magnesium content in a cow’s overall diet, stress, or excessive wet weather leaching magnesium from grazed grassland.”
What are the early warning signs?
Grass staggers can be a difficult condition to spot, and the condition often comes on so rapidly that a cow will show no prior symptoms.
“A sudden reduction in milk yield can be an early warning sign, but visual symptoms include restlessness, twitching muscles, grinding of teeth, convulsion, loss of appetite and even paralysis,” continues Sue. “If one cow is displaying symptoms, farmers need to be hyper-vigilant across the whole herd. While only one cows may be displaying major symptoms initially, the likelihood is that low magnesium levels will be negatively affecting more cows.”
How to prevent grass staggers?
General management steps can be taken to help reduce the risk of grass staggers, such as slowly transitioning cows on to spring grass and avoiding sudden reductions in supplementary feeding. However, the core principle to follow is to provide cows with access to a regular supply of magnesium in their diet – especially during the early grazing period.
“Cows can be fed free access high-magnesium minerals or supplementary feeds with minerals already mixed in,” continues Sue. “ForFarmers supplies a range of different minerals, including the Minline Grazer Mineral that has been specifically formulated to complement grazing systems. This mineral contains 20% magnesium, so a typical feed rate of 100g per cow/per day provides 20g of high-quality magnesium."
“One other consideration to take is to ensure adequate levels of sodium in a cow’s diet. The absorption of magnesium into the blood stream is reliant on sodium, so ground rock salt, PDV salt or lump rock salt must be fed alongside any magnesium supplement.”
Complementary grazing compounds
As well as hypomagnesaemia, the early grazing period poses several other challenges that dairy farmers must manage. While grazed grass is a low-cost feed option, its nutritional value is highly variable, so accurately balancing a cow’s nutritional intake during the grazing period is far from straightforward.
“Grazed grass is a fantastic resource, but to ensure that cows are getting all the nutrition they need to help support milk solids, good health and fertility, feeding with supplementary compounds during the grazing period is a good idea,” explains ForFarmers’ Product Manager, Bruce Forshaw. “Spring grazing also provides cows with grass that is very high in energy and crude protein, and this can cause significant challenge to rumen function.”
ForFarmers’ GrazeMate compound feed has been specifically formulated to complement spring grazing and help cows get their grazing period off to a good start. “GrazeMate includes Levucell, which is a rumen specific live yeast that helps to stabilise rumen function,” continues Brue. “Recent trials have shown that Levucell helps to improve digestion, firms dung and improves milk solid production in cows at grass.
“The compound is also rich in starch to ensure that cows are provided with a good level of glucose, that mobilisation of body reserves is reduced and dry matter intakes are supported. The aim is to provide grazing cows with all the key nutritional elements they need to support high performance, while also utilising grazed grass.”