A successful transition from the dry period to lactation is one of the most critical moments in the life of a dairy cow.

Iowa State University Veterinary Medicine
College professor Dr Jesse Goff.

Dr Jesse Goff, a professor at Iowa State University Veterinary Medicine College, discussed how farmers can optimise their dairy herd’s transition period, focusing on hypocalcaemia and milk fever in cows.

He said: “I often think of hypocalcemia as a gateway disease, because it has fairly substantial effects on the immune system of the cow.

It affects dry matter intake, which is eventually going to cause, or exacerbate, negative energy and protein balance.

“And we know that hypocalcaemia is a risk factor for mastitis, displaced abomasum, retained placenta, and metritis of cows. So I think anything we can do to prevent hypocalcaemia will help minimise a lot of these secondary diseases of the cow.”

When cows begin to calve and lactate they lose a large amount of calcium from the bloodstream to the mammary gland which often causes a substantial drop in blood calcium concentration.

Dr Goff discussed various methods of adding lacking minerals to diets at different stages of the cow both before and after calving.

He said: “Now pre-calving, if you using an anionic product, almost every one of them has magnesium sulphate or magnesium chloride in them. And these are anions, but they’re also going to supply magnesium in a readily available, very soluble form. So you don’t have to worry about pre-calving magnesium.

“The problem arises post-calving, when most nutritionists are going to switch that cow to magnesium oxide as the source for magnesium. The problem is, magnesium oxide is not all the same.

“Also, farmers need to keep dietary phosphorus close to the cow’s requirements, about 0.23%,” he added.