Ketosis: The theory

Energy source

The body’s response to a lack of feed is to look for an alternative energy source, so she mobilises her stores of fat which are metabolised in the liver.

“These fats are a good fuel and their breakdown involves the production of ketone bodies – themselves a source of energy.” But ketone bodies have other effects on the cow, including appetite suppression, milk yield reduction and a negative effect on fertility as the body seeks to cope with its lack of energy intake.

“Ketones have an almost toxic effect on the developing egg,” says Mr Campion.

“You have to remember the egg you want to be fertilised, about 50- 70 days after calving, is an egg which was developing about two months or so earlier, at the height of negative energy balance.”

This means the time just before and around calving is critical to fertility, so everything should be done to minimise stress and condition-loss when the egg is developing.

“The other side of the story is the issue of fatty liver which is closely linked with ketosis and the chemical pathways involved,” he says. “If too much fat is mobilised, the liver will be unable to cope and it will ultimately lose its ability to metabolise anything well.

“Around calving, the immune system is compromised and any degree of negative energy balance will exacerbate this effect, leaving her more prone to metritis, mastitis and other infectious diseases, and in the worst cases leading to her death.”

However, Mr Campion says good management – including keeping the rumen full and minimising stress – can keep ketosis under control, and he comments on a new tool which can significantly improve a potentially difficult situation.

“We now have a bolus to help manage ketosis, which has been proven to reduce incidence in 74% of cows,” he says.

“It is something I would turn to whenever I suspect a problem – perhaps in fat cows, in those with a history of the disease or in those carrying twins. It is certainly helping many of our clients keep their ketosis rates down.”

• Next month: Ketosis in practice and prevention tips