How to prevent milk fever in dairy cows
Clinical milk fever in dairy cows can cost around £200-£300 per case. The disorder can also exacerbate the risk of secondary issues such as ketosis and mastitis.
As part of our Time4Tranisitioning series, we have put together a reminder guide on the signs of milk fever, also known as hypocalcaemia, and how to prevent it below:
What is milk fever?
Milk fever is a metabolic disorder caused when the blood calcium levels of freshly calved cows drop below the normal range (2.1-2.4mmol/L). This drop is a result of the imbalance between the calcium demand post-calving and what is absorbed from the diet or mobilised by the cow.
Older cows respond more slowly to the rapid increase in demand for calcium post-calving so are typically more susceptible to milk fever. Those with a higher body condition score are also at greater risk.
Milk fever can either be clinical, determined by cows having less than 1.4mmol/L blood calcium, or subclinical, in which cows have between 1.4 to 2.0mmol/L blood calcium.
Symptoms of subclinical cases can be hard to identify, but the symptoms of clinical cases can be broken down into three grades of severity:
Symptoms of milder cases of clinical milk fever include:
- Lack of appetite
- A drop in milk yield
- Cold ears and nose
- Uncoordinated walking
Symptoms of more severe cases of clinical milk fever include:
- Low body temperature
- Difficulty standing
- Sternal recumbency – cows sitting on their brisket with their legs tucked underneath
Symptoms of the most severe cases of clinical milk fever include:
- Lateral recumbency – cows lying on their sides
- Rumen bloat
Ensuring a correctly balanced diet pre and post calving is the best way to prevent milk fever. Make sure you read our guide on dry cow nutrition and implement the following dietary measures:
- Limit the amount of calcium pre-calving. Aim for 30g/head/day. If too much calcium is supplied in the diet during the dry period, the mobilisation of calcium from the bones and absorption of calcium from the gut can be impaired post-calving
- Avoid feeding high potassium forages pre and post-calving, such as good quality grass silage and feed salts that contain chloride. This will help to keep the blood pH level from becoming alkaline which would reduce calcium mobilisation. Aim for potassium levels that are between 1.3-1.5% DM by providing whole crop, maize silage or straw as forage
- Make sure transition cows receive high levels of magnesium pre and post-calving to help with calcium mobilisation. Aim for 40g/head/day and consider providing a supplementary mineral block or bucket or adding powdered minerals to the TMR if this cannot be achieved by the inclusion of forage
- Consider bolusing high-risk cows immediately after calving
Don’t forget you can contact your local on-farm specialist if you would like assistance with forage analysis or formulating transition cow diets.
Although milk fever prevention should be a key priority for dairy farmers, treatment will be required should cows present symptoms.
Administer calcium via an oral drench, bolus or injection to cows with milder symptoms and monitor them closely. Those showing more severe symptoms will require veterinary attention and intravenous calcium salts.