Feeding DC X-Zel for over 7 years
Neil & David Kidd of Booth Hall, Lancashire, feeds…
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:
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:-
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:
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.
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