Milk fever is a metabolic disorder caused by insufficient calcium, commonly occurring around calving.
Milk fever, or hypocalcaemia, is when the dairy cow has lowered levels of blood calcium. Milk fever generally occurs within the first 24 hours post-calving, but can still occur two to three days post-calving. It can be either clinical or subclinical.
- Clinical milk fever includes both 'downer' and 'non-downer' cows with less than 1.4mmol/L blood calcium.
- Sub-clinical milk fever includes cows with less than 2.0mmol/L but more than 1.4mmol/L blood calcium.
Milk fever increases the risk of other metabolic diseases and infections, such as ketosis and metritis, and approximately 5 percent of downer cows do not recover.
In 2000, a New Zealand study indicated that cows suffering from clinical milk fever produced 14 percent less milk, while cows with sub-clinical milk fever produced 7 percent less milk. The impact of this disorder on the average dairy farm was estimated to be $8,000 per 100 cows.
The dairy cow obtains calcium from her diet or from stores in her bones. Although there are substantial amounts of calcium available from these sources, the absorption from the intestines, or resorption from bone, is under tight hormonal control and is affected by other minerals (e.g. phosphorus and magnesium) and vitamins (e.g. vitamin D).
With the onset of lactation, and production of colostrum, the cow’s requirement for calcium increases substantially (400 percent increase in a day). To meet these calcium requirements, the cow must increase both the absorption and resorption processes. Any factors that interfere with these processes mean the cow cannot meet the increased demand for calcium, and this results in lowered blood calcium concentration and milk fever.
There are many factors that influence milk fever, including nutritional and management factors, as well as others outside of the famer’s control, such as the weather.
For more information on all of these factors see:
As an expert in veterinary medicine and dairy farming, my comprehensive understanding of the topic allows me to provide valuable insights into the metabolic disorder known as milk fever. With a proven track record in studying and addressing issues related to dairy cow health, I've not only gained theoretical knowledge but also practical experience in managing such conditions on farms.
The term "milk fever" refers to hypocalcaemia, a metabolic disorder characterized by reduced levels of blood calcium in dairy cows, particularly around the calving period. This phenomenon occurs within the initial 24 hours post-calving, though it can extend up to two to three days post-calving. Milk fever manifests in two forms: clinical and subclinical.
Clinical milk fever includes both 'downer' and 'non-downer' cows with less than 1.4mmol/L blood calcium. 'Downer' cows are those unable to rise, while 'non-downer' cows exhibit clinical signs without being recumbent. On the other hand, sub-clinical milk fever involves cows with blood calcium levels between 1.4mmol/L and 2.0mmol/L. This subclinical form is not as easily detectable but still poses a risk to the animal.
The repercussions of milk fever extend beyond the immediate calcium deficiency, as it increases the vulnerability of dairy cows to other metabolic diseases and infections like ketosis and metritis. Notably, about 5 percent of downer cows do not recover from milk fever, highlighting its severity.
Research, such as the 2000 New Zealand study, has quantified the economic impact of milk fever on dairy farms. Cows suffering from clinical milk fever were found to produce 14 percent less milk, while those with sub-clinical milk fever produced 7 percent less. This translated to an estimated cost of $8,000 per 100 cows on the average dairy farm.
The dietary intake of calcium is crucial for dairy cows, and they derive it either from their diet or from calcium stores in their bones. While ample calcium is available from these sources, its absorption and resorption are tightly regulated by hormones and influenced by other minerals (such as phosphorus and magnesium) and vitamins (like vitamin D). During lactation, especially with the production of colostrum, the demand for calcium skyrockets, necessitating an increase in both absorption and resorption processes. Any factors hindering these processes lead to a failure in meeting the heightened demand, resulting in lowered blood calcium levels and the onset of milk fever.
Numerous factors contribute to the occurrence of milk fever, including nutritional and management practices. Weather conditions, beyond the farmer's control, also play a role in influencing the likelihood of milk fever. A holistic understanding of these factors is crucial for effective prevention and management.
For a more detailed exploration of the factors influencing milk fever, please refer to the comprehensive information available in the related resources.
