Following a trip to Minnesota and Wisconsin as part of Zinpro’s Three Trucks Trip, Anna Haigh has summarised Luciano Caixeta’s thought-provoking paper on negative balance in transition below:

Ketosis can be described as the maladaptation of a cow to the 300% increase in energy demand from peak milk yield. Ketosis can be diagnosed as a rise in blood ketone level (BHBA) above 3mmol/litre; however this only covers clinical cases. Subclinical ketosis, BHBA levels greater than 1.2mmol/litre, may not be seen visibly in the animal but it is an underlying problem costing around $117 (£89) per case.

The financial penalty associated with ketosis is not only due to a loss of milk (up to 110kg milk per case), but also as a result of the increase likelihood of ketotic cows having a higher susceptibility to other health issues. LDA risk may increase by up to 3.3 times and losses before 60 days in milk up to 2 times. Fertility is also affected, non-ketotic cows are 1.5 times more likely to achieve pregnancy at first service and have a shorter calving interval.

Negative mineral balance is also an issue surrounding calving and transition, for example a cow will experience a 60% increase in calcium (Ca) demand after calving. Colostrum contains 2.3g of Ca per litre and this has to be met by:

  • Increase in the mobilisation of Ca from the cow’s bones

  • Increase in absorption of dietary Ca

  • Increase in the absorption of Ca through the kidneys

It is difficult to determine a subclinical vs. a clinical case of milk fever by blood Ca level as not all clinical cases see a drop of blood Ca below 5.6mg/dL. As with ketosis, subclinical cases of milk fever can go undetected and can occur anywhere between 25 to 73% of the transitioning herd, costing around per case $246 (£185). Cows experiencing hypocalcaemia are 3 times more likely to develop and LDA, 2 times more likely to be culled less than 60 days in milk, lose milk and increase their chance of retained foetal membrane and uterine disease.

A DCAD diet can aid in the reduction of subclinical and clinical milk fever incidence. Caixto explains this using “the 3 W’s and the 2 H’s”:

  1. What is DCAD? The difference in dietary sodium and potassium ions (cations) and chlorine and sulphur ions (anions).

  2. Why use DCAD? To prepare the transitioning dairy cow for increased calcium metabolism from high Ca demands of colostrum production and early stages of lactation.

  3. How to use DCAD? A negative DCAD will acidify the blood, this will enhance mobilisation of bone Ca stores and gut absorption of Ca.

  4. When to use DCAD? DCAD should be achieved during the close up dry cow period, at least 10 days before calving.

  5. How to monitor if DCAD is working? This acidification can be measured as a drop in urine pH to 6.5-7 across the herd.

Although some state of negative energy balance may be harder to prevent in the high yielding herds we see today, milk fever can be prevented by the close management of the dry cow diet prior to calving. It is the close attention to detail and monitoring of the herd than will aid in the prevention of these disorders occurring in transitioning dairy cows.