MAKING THE most of lush autumn grazing with dry cows has led to more cases of milk fever and its associated problems, reports Somerset-based vet Paddy Gordon.
“We’re seeing more uterine prolapses, downer cows and assisted calvings which happen because calcium affects muscle tone,” according to Mr Gordon of the Shepton Vet Group. These cows are also more likely to suffer from Whites, which is linked to poor fertility.
Autumn grass is high in potassium and low in magnesium which counteracts the milk fever control used in dry cows. “Feeding a high magnesium diet decreases calcium available to the cow and makes her more efficient at using it from the gut and mobilising it from her bones,” explains Mr Gordon.
Because the cow can’t store magnesium, she depends on her daily intake. “Each day she has low magnesium grass – or high potassium – the risk of milk fever increases.”
Mr Gordon advises not relying on grazing alone for dry cows, particularly when close to calving. Feeding round bale silage will dilute the effects of lush grazing.
“Where there is a single dry cow group, supplement with magnesium flakes in the water or top dress on silage.”