21 June 2002

Blood profiles spot energy gaps

Cow longevity and business

planning were some of the

topics discussed at the Dairy

Solutions 2002 conference,

held at the Royal Agricultural

College, Cirencester.

Richard Allison kicks off

with metabolic profiling

ENSURING cows consume adequate energy is one route to good fertility, but how do you know whether a ration is meeting their energy requirement before it is too late?

One solution is to ask cows being fed the ration in question, University of Edinburgh vet consultant David Whitaker told delegates at the joint SVG Intermol and farmers weekly conference. "This is the aim of metabolic profiling."

Dairy rations can be assessed by a number of methods, such as changes in milk output and composition, body condition and fertility. However, it is often too late once changes in body condition and fertility are observed.

Getting rations wrong during the first month of lactation will lead to reduced conception rates, as late as 100 days after calving, which is nearly two-and-a-half months after the nutritional imbalance was resolved, said Dr Whitaker.

"In addition to providing an early indication of nutritional problems, metabolic blood profiling provides information on what is wrong with the ration and what is about to go wrong."

But Dr Whitaker said it must be undertaken properly. "Blood sampling should be done soon after the ration change. Leaving it too late can result in a normal blood profile as the cow may be back into positive energy balance after the damage has been done.

"Selection of cows is also crucial. Ideally choose seven in early lactation, five in mid lactation and five in the early dry period.

"Cows in mid lactation offer a within herd comparison to indicate whether the problem is diet or poor intake."

He believes the most important compounds measured in blood are beta hydroxy butyrate, non-esterified fatty acids and glucose. They indicate whether cows are breaking down body fat and have a severe energy deficit. Urea is also useful, as a low value indicates a rumen energy deficiency.

"Of samples submitted to our lab, more than half of cows in early lactation are energy deficient. This goes down to 10% for later lactation cows and 35% for those in the early dry period."

The cost of testing 17 cows is £165, which excludes vet costs for taking the blood samples. He believes its cash well spent as modern high genetic merit cows need blood profiles to know what is happening each time the ration is changed. &#42

Blood profiling provides an early indication of nutritional problems, but it must be carried out properly, says David Whitaker.

&#8226 Early indication.

&#8226 Soon after ration change.

&#8226 Cow selection crucial.