A case of milk fever can have a detrimental effect on a cow, and her production during the subsequent lactation.
As autumn-calving herds are now in the last stages of preparation for calving, the prevention of milk fever should be of great focus to farmers.
Autumn calvers are often more prone to milk fever, but with good management most cases can be avoided.
Milk fever is characterised by reduced blood calcium (Ca) levels. It is most common in the first few days of lactation when the demand for Ca for milk production exceeds the body’s ability to mobilise calcium reserves.
It can also be seen in late-pregnancy, right up to the point of calving.
Proper management of cows in the lead up to calving is really important in order to prevent as many cases from occurring as possible.
Milk fever
Autumn calvers should be grouped based on body condition score (BCS) and fed accordingly.
During the late summer, cows can easily become overfat, which not only increases the risk of milk fever, but calving difficultly too.
Like spring-calving cows, feeding minerals is extremely important; feeding the correct minerals can help prevent a large number of issues.
Good-quality minerals should be fed four to six-weeks pre-calving, particularly when cows are dry at grass in late summer. A bolus cannot replace minerals being fed daily to cows pre-calving.
Steps to preventing milk fever in autumn-calving cows:
- Have cows in the correct BCS at calving (3-3.25);
- Reduce calcium intake before calving and avoid any added oral calcium. This will allow the cow to mobilise her own calcium from bone or blood immediately after giving birth;
- Avoid lush pasture for autumn-calving cows, as this grass is low in magnesium;
- Feed a good-quality dry cow mineral that is high in magnesium and has either no added calcium or low added levels;
- Feed forages that are low in potassium and have not received potassium fertiliser or slurry.