Why we need a perfect calcium balance at calving

Calcium levels at calving are crucial for easier calving, successful future lactations and the general health of your cows. More importantly the consequences of not having the correct balance of calcium can have a costly effect on the farm, through sub-clinical milk fever that's rarely seen or treated.

Why we need a perfect calcium balance at calving

Our key focus at Advanced Nutrition is animal health and the dry period is a significant part of the cow's life cycle where improvements in cow health can provide significant gains. One particular part that the team looks at is the calcium levels at calving, because these levels not only effect the cow at the point of calving but if calcium levels are low it can affect both the heifer and the calf for the rest of their productive lives. Low calcium levels are also associated with a wide range of metabolic issues that can be costly to the farm, even resulting in a cull cow.

The correct balance of calcium at calving is crucial for proper muscle function and the immune system. At this point there is a sudden demand for calcium and the resultant drop in the required level can impair the cow’s health status and productivity.

During the final stages of pregnancy, most dry cow diets contain more calcium than is required, consequently the cow is only passively absorbing calcium. However, at calving when there is a sudden demand for calcium for colostrum production and also for muscle contractions relating to calving and udder function, and the required level simply cannot be met by passive absorption. Active calcium absorption and mobilisation is required, yet it takes between 24 and 48 hours for her to change to active absorption, consequently there is always a drop in calcium levels around calving.

This dip in calcium levels is known as hypocalcaemia or milk fever in dairy cows. It's defined as situations where the blood calcium concentration is below normal (normal plasma Ca being 2.1-2.8 mmol/l). Cows suffering from hypocalcaemia can be divided into two groups:

  • Clinical milk fever
    Dairy cows experience milk fever and display well know symptoms

  • Sub-clinical
    Dairy cows show no clinical signs of milk fever, however blood calcium concentrations drop below 2.0mmol/l and cows become highly susceptible to secondary conditions.

Cows suffering from milk fever are between four and nine times more likely to suffer from a range of other metabolic orders, many of which are related to each other. Each come with a serious cost implication not only in treatment and vet costs, but also with losses from future milk and fertility delays. 

Research has also shown that cows with milk fever are likely to suffer:-

  • 6 times more dystocia/ calving difficulties
  • 4 times more cases of retained placenta
  • 9-fold increase in the incidence of ketosis in cattle
  • 4-fold increase in the incidence of left displaced abomasum

What's also not considered, is even a very small reduction in normal calcium levels can seriously impact production and profitability.

A small decrease in blood calcium can increase the risk of:

  • Displaced abomasum
  • A negative energy balance
  • Reduce reproductive performance
  • Lower milk production

How to treat low blood calcium

Quite often intravenous calcium is used and although this will give a rapid response to a clinical case and often save a cow’s life, it doesn’t reduce the problem. Additionally IV calcium, may cause fatal cardiac problems and perhaps most significantly, shut down the cow’s own ability to mobilise the calcium she requires at this critical time. Cows treated with IV calcium often suffer a hypocalcaemic relapse 12 to 18 hours later.

Subcutaneous and oral calcium supplementations can be given around calving but are often not given as required and there is only a small amount of absorption. Energy drenches can be used to provide a quick response to energy deficiency. Neither of these offer a preventative effect and both are poor for reducing subclinical hypocalcaemia/ milk fever.

Since both clinical and subclinical milk fever and consequential metabolic disorders are mainly related to the cow’s diet, the challenge is to maintain her feed intake and rumen balance around and shortly after calving. However, it is important to manage the cow carefully during the entire dry period to minimise fat deposition in the liver, maximise liver health and therefore also improve ovarian development for the next lactation and fertility cycle.

  1. Maintaining cow condition is critical 
    Target condition score 3 at drying off and calving to prevent fat being laid down inside the cow, especially in her liver otherwise it will reduce her ability to control her own mineral balances, in particular calcium. During the dry period, target feeding 9MJ/kg ME with a 12kg DM intake.
  2. Achieving the correct calcium balance around calving – X-Zelit
    X-Zelit is a calcium binding additive containing synthetic zeolite. This product binds calcium from the diet during the last two weeks prior to calving. The additive stimulates the cow’s hormonal system to actively absorb and mobilise calcium to ensure she is fully ‘fired up’ at the time of calving. Cows are subsequently more energetic, have higher feed intakes and are ‘ready to go’. Consequently they are less likely to fall in to energy deficit and also suffer fewer metabolic issues. This is a scientifically proven strategy, that has been working for farmers for over 10 years.
  1. Paying attention to detailed feed management
    Housed dry cows should be stocked at approximately 75% normal rate, ideally 10m2for the average Holstein cow and at least 80cm trough space should be provided per cow with food pushed up at least four times per day.


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