Milk fever is unfortunately an issue that will likely have to be dealt with on farms calving cows this autumn.
A case of milk fever can have a detrimental impact on a cow’s performance during her subsequent lactation, so cases should ideally be avoided.
Cases can occur prior to calving, but the majority of cases will be seen in the period shortly after the cow has calved when calcium demand is high.
Known as ‘the gateway disorder’, milk fever occurs due to the onset of lactation, placing a huge demand for calcium (1.2–1.5g/kg of milk) on the cow.
If calcium supply does not meet demand, the cow will become deficient in the mineral.
Milk fever is most common in the first few days of lactation when the demand for calcium for milk production exceeds the body’s ability to mobilise calcium reserves.
A primary role of calcium in the cow is in muscle contractions – therefore a cow with either clinical or subclinical milk fever is at increased risk of developing a host of problems.
The period from three weeks prior to calving and three weeks post-calving, is known as the transition period.
During this period, cows face a number of physiological challenges, which if not managed correctly, can result in metabolic issues.
Examples of issues that can arise during the transition period include: Udder oedema; milk fever; retained placenta; displaced abomasum (stomach); laminitis; metritis; ketosis; and fatty liver syndrome – all of which result in lost profits.
Management prior to calving is vital, which includes ensuring that cows are fed adequate minerals and that body condition score (BCS) is monitored.
Cows that are in too high of BCS should be classified as being high risk for developing issues during the transition period.
Early treatment of cows that suffer from milk fever is vital; a case will often occur when you are busy, or in an area that is not ideal for treatment, including the collecting yard or cubicle shed.
At a time of year when dairy farmers are already busy, such fever cases can increase stress levels on farms.
Because of this, any cows that may be at risk need to be monitored closely and treated promptly if symptoms appear.
Generally, cows recover quite quickly when they are given a calcium injection or bottle subcutaneously or true dissolving bolus.
In severe cases veterinary assistance may be required.
Once a cow is confirmed to have milk fever, it is important that she is closely monitored, as other metabolic disorders can then occur during the lactation.