Ketosis is a metabolic disorder of dairy cows, which commonly affects animals during the transition period.
As cows enter the final stages of pregnancy and move into the early stages of lactation, energy demands are generally not met by dry matter (DM) intakes.
This results in cows entering a negative energy balance with a prolonged period – resulting in a clinical case or sub-clinical case of ketosis.
A study suggests that the energy requirements of cows then increases by 300% during early lactation, which is a big reason why cows struggle to get enough energy from their diet.
Although perceived by many to be an issue with high yielding cows, research has shown that this is also an issue within grass-based seasonal herds.
Research also indicates that up to 50% of freshly calved cows experience some sort of disease, and up to 75% of the diseases that occur on farms happen during the transition period.
Ketosis
Brian McConnell, a technical advisor with Elanco, speaking to Agriland, and explained that ketosis is a build-up of ketones or ketone bodies in the blood.
There are three different types of ketone bodies, and one of these is reasonably easy to test for on farms.
McConnell said that the test is looking for Beta-Hydroxybutyrate (BHB) i.e., excessive ketones in the blood due to a negative energy balance (NEB).
NEB is caused by cows having an excess demand or requirement for energy, compared to the DM intake of the cow.
The key time for the development of this issue is during the transition period, shortly before and after calving.
McConnell noted that energy requirements of cows increase significantly at the end of pregnancy due to foetal growth, colostrum production and in early-lactation due to milk production.
He said: “This is coupled by a decrease in DM intakes around calving, with the key being to keep DM intakes up during this period.
“Almost every cow will have an energy gap, and you are trying to minimise that gap as much as possible; the cows that struggle to minimise that energy gap between what they need and what they are eating, will enter into ketosis.”
McConnell explained that you can look at ketosis in two ways, with clinical and sub-clinical cases.
He said: “Clinical ketosis is what most farmers think of when you mention it – that will be a cow that has had a reduction in appetite, has gone off her feed and has dropped in milk production.
“But if you have clinical cases, that is a sign that you [probably] have a lot more [undetected] sub-clinical cases going on within your herd.
“Almost every herd will have sub-clinical ketosis to some degree, and you are trying to limit the number of cases – but it is going to very difficult to eliminate it altogether.”
Sub-clinical cases can be detected through monitoring with the help or your vet.
Irish study
A study completed by Elanco on Irish grass-based seasonal herds has determined that 27% of the cows in the herds included in the study had ketosis or sub-clinical ketosis.
This means that these cows were not reaching their full potential, with McConnell noting that a lot of these cows would go completely unnoticed.
McConnell said: “The reason we don’t want cows to be affected by sub-clinical ketosis, is that it has negative consequences for general health, fertility and milk production.
“If you limit the number of cows affected by sub-clinical ketosis, then you should improve the health status of your herd, especially related to the transition period – improve fertility and cows should be able to reach their full potential.”
Prevention
To identify cows that are most at risk to developing ketosis, McConnell said that farmers should used the acronym SOFT (Sick, Old, Fat and Twins).
This includes cows that have health issues, are older, over-conditioned or were carrying twins.
While it is important to monitor these cows, he noted there are other outliers that do not fit into the acronym.
Other at risk cows include those with longer dry periods (over two months), heifers that are calving down over 27-months-of-age, and those with a high fat/protein ratio early in the previous lactation, following calving.
Commenting on measures that farmers can adopt to prevent or reduce cases of ketosis within their dairy herds, McConnell said: “As important as being in the right body condition score (BCS) is, it is important to reduce the change in condition score during the transition period.”
He explained that cows losing excessive body condition is a sign that they are mobilising fat, which is the reason we get high ketones in the blood.
Consulting with a nutritionist is very important during that transition period in order to ensure that feed is tailored to the requirements of your cows.
Another important factor that McConnell noted, was that you could have the perfect ration or diet presented in front of the cow, but if DM intake is not where it needs to be, cows will have an energy gap.
Anything that could decrease DM intake needs to be assessed – whether that is housing, feed space, comfort of the bedding, social factors and lameness.