Milk Fever - A Vet's Perspective


Clinical milk fever incidence is currently running close to 10% in UK dairy herds. It's costing approximately £200 per cow, while subclinical milk fever can affect up to 75% of the herd, it's unrecognisable and generally remains untreated according to Advanced Nutrition's Veterinary Nutritionist, Debby Brown.


Milk Fever - A Vet's Perspective

Milk fever - both clinical and subclinical, occurs when a cow calves. Calving is probably the most stressful time in a cow's life: she will be changing environment, diet and group all at the same time, as well as undergoing massive physical challenge. Milk fever incidents also increase with the number of lactations.

That's not all. Cows suffering from milk fever are between four and nine times more likely to suffer from a miscellany of other metabolic disorders, many of which are related to each other. They each come with a significant price tag, not only in treatment and vet costs, but also with losses from future milk production and fertility delays.

During the final six to eight weeks of pregnancy, most dry cow diets contain more calcium than is required, consequently the cow is only passively absorbing calcium for colostrum production and also for muscle contractions relating to calving and udder function, and that required level simply cannot be met by passive absorption alone.

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.

Treatment

Intravenous calcium will give a quick response to a clinical case and often save a cow's life however, it doesn't reduce the problem; intravenous calcium, may cause fatal cardiac problems and perhaps more significantly, shut down the cow's own ability to mobilise the calcium she requires at this critical time. Cows treated with intravenous 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.

Prevention

Since both clinical and subclinical milk fever and consequently 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 and maximise liver health. This also improves ovarian development for the next lactation and fertility cycle.

1. Maintaining cow condition is critical:

Target condition score 3 at driving off and calving will prevent fat being laid down inside the cow, particularly 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, a calcium binding additive containing synthetic zeolite - a product initially designed to reduce the build-up of limestone from hard water in washing machines. Since then, X-Zelit has been developed to bind calcium from the diet during the 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" around 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 suffer fewer metabolic issues.

- DCAB diets work reasonably well. However, they require good management and monitoring and are not suitable for all farms. They can also reduce appetite at this critical time.

3. Paying attention to detailed feed management

Housed dry cows should be stocked at approximately 75% normal rate, ideally 10m2 for the average Holstein cow. At least 80cm trough space should be provided per cow with food pushed up at least four times per day.


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