Lush grass casuing metabolic disorders

Grass staggers and milk fever cases in dairy cows and sucklers could hit a peak in the coming weeks given the sudden flush of grass, vets are warning.

Already in the past month vet Maarten Boers of The Livestock Partnership has seen a significant rise in milk fever cases in dry cows close to calving, which coincided with an increase in lush grass late in the season.

“Dairy farmers may be underestimating the sudden rise in grass growth which has led to a number of milk fever cases in cows around calving. The problem with milk fever is those cows affected by the metabolic disorder are more prone to uterine prolapse,” explains Mr Boers.

Farmers who are making the most of this late summer grass with dry cows are the ones likely to encounter problems, he says.

“Grass is high in potassium and low in magnesium at the moment and, because the cow can’t store magnesium, she depends on her daily intake. Each day a cow has low magnesium or high potassium grass the risk of milk fever increases,” he says.

Dietary cation-anion balance (DCAB) diets and magnesium supplementation can both help in its control, says Rob Howe of Lambert, Leonard and May, Lancashire. “DCAB diets are an intensive way of trying to reduce chances of milk fever and for this reason it’s important to involve a nutritionist. The classic way to control milk fever is by feeding dry cow rolls, but you can also add magnesium chloride in the water too,” he suggests.

Dairy and beef farmers also need to be on their guard for grass staggers (hypomagnesaemia), warns Andy Biggs of The Vale Vet Group. “Cattle most at risk will be suckler cows close to calving and potentially also dry cows, this is because the grass is low in magnesium and the cow requires a daily source. Adequate magnesium supplementation is, therefore, required to prevent cases from occurring.”

Adding straw or silage to the diet of sucklers and dry cows could also help slow down digestion, which will allow more time for the low levels of magnesium in the grass to be absorbed, adds Steve Borsberry of the 608 Vet Group.

Symptoms to look out for in the early stages of grass staggers include highly excitable cows, nervousness, trembling and later cows going down, adds Mr Boers.