As we progress further into the calving season for the autumn calving herds, the risk of milk fever (hypocalcemia) and other metabolic issues, increases.
For many autumn calving farms, calving is well underway, with the likelihood of a lot of the younger cows and heifers calving down first.
In general, younger cows and heifers are not at risk when it comes to metabolic issues, but older cows and late calving cows are at risk.
Older cows tend to go in calf that bit later than younger cows and are at a high risk of getting milk fever as they can put on too much condition due to longer amount of time dry.
At this time of the year, the main focus is on getting cows calved and due to this business, feeding dry cow minerals can be forgotten or overlooked.
Preventing milk fever
It is crucial that dry cows are receiving the correct amount of minerals per cow, which should be about 100 – 120g/cow.
The dry cow mineral should have at least 22% magnesium included and high levels of vitamin D of about 14,000 units plus – older cows are going to need high levels of vitamin D to prevent milk fever.
Cow health problems from inadequate mineral supplementation include:
- Clinical and subclinical milk fever;
- Ketosis;
- Retained cleanings;
- Low dry matter intake;
- Displaced abomasum;
- Fertility problems.
If dusting minerals on silage, minerals should be offered twice daily (60g/cow in two feeds) to try to ensure that intake is controlled and that all cows can have access to minerals and is particularly important where feed space is limited.
Trace minerals like copper, selenium, zinc and so on should be fed from at least six weeks pre-calving in order to achieve adequate levels for when they are calving down.
Some farmers benefit from running a freshly calved group of cows where they are kept indoors and left separate from the milking herd for three to four days until the colostrum period is finished.
This should be continued so freshly calved cows can get that bit of extra nutrition and care.
Later calving cows should be restricted to 10-11kg DM in November to keep body condition score (BCS) under 3.5, and if they are already over-conditioned, it may be difficult to rectify and should be managed and monitored at the point of calving.
If there has been a history of health issues, such as milk fever at calving, the mineral content of your silage should be tested.
High potassium (K) silage can often be the cause of the problem, so the farmer should target a low K silage of less than 2.2% from four weeks pre-calving.
A high calcium bolus with vitamin D is recommended instead of straight calcium bottles under the skin for the purpose of preventing milk fever at the point of calving.
