26 April 1996

Higher urea levels neednt be a worry

INCREASED milk urea levels seen at turn-out need not cause concern except when trying to get cows in calf or when milk yield drops.

ADAS nutritionist Bruce Cottrill issues his advice on the basis that spring grass will improve in quality and protein content over the next few weeks.

"The type of protein in this grass is very soluble and degradable so that the cow cannot use it all. This increases blood and milk urea," says Dr Cottrill.

The greatest influence on milk ureas, he stresses, is the balance between effective rumen degradable protein and fermentable metabolisable energy supplied to rumen bugs.

"High milk urea reflects excess ERDP that can arise from either too much ERDP or not enough FME – or both," he says. As a result dietary protein is not used efficiently. "A yield drop with high milk urea points to an imbalance of energy to protein," says Dr Cottrill. Check the amount and type of energy going into the diet.

High milk ureas in spring due to excess protein in the diet are a warning that it could be difficult to get cows in calf. To reduce proteins he advises offering low protein supplements such as sugar beet pulp or compounds.

The amount of urea present in milk is normally very small – typically under 400mg/litre (0.04%), he says.

He cautions that results from bulk milk samples reflect the situation within a herd where cows often eat widely different diets. And because the results only reflect nutrition during the previous day or so, variation may be due to short-term diet changes. &#42