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Ketosis: The tip of the iceberg

by
01 January 2014, at 12:00am

David Campion discusses a common condition and explains that for every cow showing signs of clinical ketosis there will be many who fail to reach their full potential but do not show clinical signs

IF the captain of the Titanic had paid more heed to the “tip of the iceberg” concept, the most well- known disaster in maritime history may have been averted and many souls would not have perished in the icy waters of the North Atlantic.

This expression has entered into everyday usage to illustrate an apparently small problem that hides a hugely significant issue and in many walks of life businesses and dreams have foundered because people forget the importance of the “tip of the iceberg”.

Equally there is no better expression to illustrate the problem of ketosis within the dairy herd. There are few dairy farmers who have never had a good cow suffer from milk drop and inappetence.

Closer examination reveals that the cow has lost condition since calving and indeed they may notice a sweet “pear drop” smell on the breath of the cow. The cause of this is the infamous “energy gap” of early lactation.

To understand this energy gap we have to go all the way to the dry period. During this critical period in the cow’s year she has a large calf filling her abdomen, reducing the space that can be occupied by the rumen; this in turn reduces the amount of food the cow can eat.

Genetically programmed

At calving the cow is genetically programmed to produce large volumes of milk which requires a lot of energy to produce. At the same time she is, perhaps, a little sore after calving, is stressed by having to change groups and establish herself in the hierarchy of that group.

Her diet has changed significantly and the microflora of the rumen is not able to deal with this change with maximum efficiency. Thus, it is very unlikely, even in the best case scenario, that the modern dairy cow can eat enough to meet her energy requirements.

As a consequence she starts to use the fat that she has stored through late lactation and the dry period as a source of energy. This provides her with energy but as a by- product she produces ketones. If these reach too high a level then appetite is suppressed significantly, milk yields drop and the cow is deemed to have clinical ketosis. 

Treatment involves trying to reverse the changes by giving propylene glycol as a glucose precursor, boosting appetite with vitamins and trying to reverse some of the metabolic changes with steroids. The cow may go on to develop fatty liver which is very challenging to treat or she may respond to treatment but have lower than expected yields, poorer fertility and other health problems.

Although fat mobilisation is a reality for most, if not all modern dairy cows, not every cow will develop ketosis. However, some factors increase the likelihood of ketosis developing.

Fat cows at dry off have a reduced dry matter intake throughout the dry period and this further suppresses the appetite post-calving. It is of paramount importance to manage the late lactation cow to avoid excessive fat deposition. This is best done by avoiding a prolonged lactation (by getting them in calf earlier) and feeding for yield (especially difficult in smaller herds feeding TMR).

Any post-calving problems such as retained foetal membranes, mastitis or metritis are also likely to reduce voluntary food intake after calving and increase the risk of ketosis. To avoid post-calving problems careful management of the transition cow is essential with regards to mineral intake, etc. Early detection and aggressive treatment of any problem is of paramount importance.

Sub-clinical cases

Now for the “tip of the iceberg” lesson. For every cow showing signs of clinical ketosis there will be many cows who fail to reach their full potential but do not show clinical signs. These cows are described as suffering from sub-clinical ketosis.

They show no signs but are nonetheless held back by the ketones in their body. Not only will their yields be reduced but their fertility will be suppressed and they will be more prone to other conditions such as LDAs, mastitis and metritis.

These cows are very difficult to identify. As a result they often escape without treatment and end up with a long calving interval or culled for a variety of reasons, with scarcely a thought as to why these problems have developed.

Glucometer

To detect cows suffering from ketosis we need to measure the amount of ketones in the blood. This can be done using blood samples and a simple glucometer such as is used by diabetics.

This works well but is a little bit of a hassle and requires an ability to blood sample cows.

Another method is to take a milk sample and use the wonderfully- named Rothera’s reagent which turns pink when ketones are present in the milk. This is good for clinical ketosis cases but does not detect many of the sub-clinical cases. Test sticks that detect ketones in urine have also been used with some success but it can be somewhat time-consuming waiting for a cow to urinate.

Recently Elanco has launched a test strip that can be used on milk. As cows are milked at least twice daily, sample collection is easy and the strip gives a colour change that varies in intensity depending on the amount of ketones present in the milk. This semi-quantitative test is quick, easy and accurate enough to give a measure of the incidence of ketosis within the herd.

Samples taken from many herds throughout the UK have shown that there is an incidence of around one in three cows in the UK. This is causing significant financial loss to the farmer through reduced yields, increased disease incidence and also an increased culling rate.

Elanco has also recently launched a treatment aimed at preventing ketosis and thus reducing the losses associated with the problem.

It comes in the form of the Kexxtone bolus, which is designed to be given to dairy cows or heifers 3-4 weeks before calving and releases monensin for 95 days once it’s placed in the rumen.