Metabolic profiling cows during the dry period can help improve their health, production and fertility because the data it provides allows changes to be made to cow diet to ensure they have the correct energy balance when they are in milk.

If the energy status of the dry cow can be established, it is possible to adjust their diet to prevent energy deficiencies, says vet David Staak, of Market Hall Vets, St Clears.

Cows that enter lactation in a negative energy balance are more likely to show poor bulling behaviour, have lower conception rates and are more prone to becoming cystic, he points out.

Blood samples are taken from cows between day 10 and day 5 pre-calving when the level of non-esterified fatty acids (NEFAs) and beta hydroxy butyrate (Bhb) can be measured.

Cows with high levels of NEFAs may be mobilising fat at an excessive rate to compensate for low energy intakes in the pre-calving period, says Mr Staak.

“High levels of Bhbs or ketones will also indicate that cows are utilising ketones as an alternative energy source if they are not receiving adequate levels of energy before they calve.’’

Both BHbs and NEFAs would be raised in cows with fatty liver syndrome where the liver is unable to produce enough energy for the cows needs or where the cows are not receiving enough energy form their diet.

“Raised levels of NEFAs and ketones in the dry period would spell trouble for the cow in her forthcoming lactation in terms of being unable to produce enough energy for lactation and in order to resume normal reproductive activity again,’’ Mr Staak warns.

He suggests that the dry period is now accepted as the most important phase of production in a dairy cow’s lactation cycle.

During this period, the mammary gland has a chance to involute and repair any damage that occurred in the previous lactation. A dry period of six to eight weeks allows the mammary gland to rest, recover and regenerate in preparation for the next lactation, says Mr Staak.

The cow’s feet also have a chance to recover as she no longer needs to stand for lengthy periods before being milked.

Mr Staak says the dry period also gives the rumen an opportunity to have a break from producing large volumes of volatile fatty acids which are fed into the liver to produce energy for the lactating cow.

As the cow approaches calving and the next lactation, it is important that her body is in the correct condition to cope with the demands of the next lactation, he advises.

“If she is too thin, then her body will not have any reserves to cope with the massive demand from producing large volumes of milk during the next lactation,’’ he says.

“Even worse, if the cow is too fat then she will be likely to have a liver that is infiltrated with fat tissue which could have a very negative effect on the ability of the liver to produce energy for the cow and on her ability to produce milk.’’