The risk of milk fever (hypocalcemia) and other metabolic issues will be on the rise as calving kicks off.
In general, the first few weeks never have too many issues as younger cows and heifers tend to calve first, and they are not as high risk as older cows.
This stems back to older cows going in calf later than the younger ones in the herd, which often results in them putting on too much condition during the longer dry-period.
Over-conditioned cows should be grouped and separated from the rest of the herd, where they may be fed a well-managed restricted diet that will not cause issues with negative energy balances.
Ideally they should be restricted to 10-11kg DM to ensure they do not go beyond a body condition score of 3.5.
However, more importantly, cows should be fed dry cow minerals during this pre-calving period, a task that is often overlooked during calving.
The transition period for cows must be correct as any lapse in management may lead to metabolic issues and subsequently, poor animal performance throughout the lactation.
Preventing metabolic issues
Dry cows should be 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 (Mg) included and high levels of vitamin D of about 14,000 units or more – 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 sub-clinical milk fever;
- Ketosis;
- Retained cleanings;
- Low dry matter intake;
- Displaced abomasum;
- Fertility problems.
If dusting minerals on silage, they 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 them.
This is particularly important where feed space is limited.
Daily magnesium supply from pre-calver mineral – depending on magnesium inclusion level and feed rate – is as follows:
What it says on the bag
20% Mg
25% Mg
100g feed rate
20g Mg
25g Mg
120g feed rate
24g Mg
30g Mg
Magnesium has an important role to play in supporting a number of the pathways in which calcium is mobilised – both from skeletal calcium reserves and re-absorption of dietary calcium.
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 that are kept indoors and left apart 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.
