Milk fever control strategy vital on farms
Many successful farmers are putting a lot of effort into developing an effective management plan for their dry cows.
The aim is to have cows drying off and calving down at conditions core 3.0.
Adequate energy, minerals and trace elements are very important.
Feed companies have developed specific feeding and management systems for the dry cow period.
Dairymaster and Alltech have combined to offer an automatic feeding system known as “cow-centric” dry cow feeding system, to ensure that each cow gets her requirements.
Nutrition Related Health Problems
As well as infertility, mastitis and production problems, which are very obvious to farmers, there are many other very serious health problems associated with having dry cows being overfed or underfed, or not being properly supplemented with minerals or trace elements.
Dr Finbar Mulligan of the UCD School of Veterinary Medicine has frequently outlined some of these diseases, including milk fever, ketosis, fatty liver, acidosis, retained placentas, metritis, difficult calvings, laminitis, lameness, mastitis and displaced abomasums.
He emphasises that up to 90% of losses associated with some of these diseases can be sub-clinical or sub-acute and thus not obvious to herd owners.
Metabolic diseases around calving time and in early lactation cause major losses on many farms and account for much of the huge difference in profitability between similar type farms.
The risks are greater in cows bred for high yields.
He suggests that preventative measures are essential, as one problem is likely to lead to others.
For example, cows that get milk fever are eight times more likely to get other problems.
Dr Mulligan says that every farmer should have a milk fever control strategy.
This should include regular body condition scoring, ensuring magnesium supplement is fed (0.4% of diet) and access limited to high-potassium and high-nitrogen forage. He says that Irish silage averages 2.3% potassium; ideally, forage should have less than 1.8% potassium.
Poor nutrition status (including minerals/trace elements) increases culling rate, increases metabolic diseases, reduces fertility, increases lameness, increases mastitis, reduces milk yield and composition, and has enormous potential to reduce profit.
Having cows too fat can be as bad as too thin.
An extremely important time for proper nutrition is in the weeks leading up to calving and in early lactation until cows are back in calf.
Research has shown that a large reduction in feed intake and energy balance before calving, which usually occurs where management and feed quality are inadequate, is related to slow and difficult calving and retained placenta, ketosis and fatty liver, displaced abomasum, reduced feed intake and production after calving, reduced fertility, and immunosuppression, leaving animals susceptible to other diseases.
The following problems are associated with cows that are too fat during the dry period:
n Long period of low intakes and negative energy after calving.
nIncreased chances of milk fever, fatty liver, ketosis, difficult calving, retained placenta and displaced abomasum.
n 30% lower feed intake in early lactation .
So there is obviously no alternative to having dry cows at the correct condition score (CS).
Ideally, they should be dried off around CS 3.0 and be maintained at that until calving.
Cows that are too thin at calving will have low production and be vulnerable to many disease problems and infertility.
Loss of condition between calving and breeding has a major effect on fertility. Large scale Moorepark farm trials indicated that cows which lost a half CS. or more have a much lower conception rate than those losing only a quarter of a CS.
Transition feeding of a few kg of concentrates for a few weeks prior to calving is very successful in many high yielding herds, because it minimises the reduction in intake before calving, and conditions the rumen for high levels of concentrates after calving.
This is particularly important in high-yielding autumn calving herds where high levels of concentrates are fed after calving.
A sudden change in diet after calving can potentially lead to acidosis where high levels of concentrates are fed.
Concentrates should be introduced very gradually, especially where transition feeding is not practiced.
Rumen pH samples from 12 herds tested by UCD indicated that a quarter of herds may suffer from sub-acute (may not be obvious) acidosis. This often leads to laminitis, reduces feed intake, causes negative energy balance, excess loss of body condition in early lactation, and reduces mounting behaviour.
Sub-clinical Milk Fever
About 5% to 7 % of cows get clinical milk fever (hypocalcaemia), where they may go down and require veterinary treatment.
However, 20 to 39% of cows can be affected by sub-clinical hypocalcaemia (milk fever) around calving and later in lactation, with symptoms such as etained placenta, slow calving, low feed intakes after calving, reduced immune system, delayed ovulation after calving, reduced fertility, and low blood calcium for up to 45 days after calving.
It is likely that sub-clinical hypocalcaemia is causing a lot of unexplained problems on dairy farms.
Where problems are suspected, they should be thoroughly investigated with blood tests etc.
Dry cow diets should be properly supplemented with high quality minerals and trace elements (Teagasc formulation), especially for six weeks before calving.
They should have sufficient bulk in their diet and concentrates should be introduced to their diets a few weeks before calving.
This reduces the period of inadequate intake before and after calving.
