There were 10 calved the last time I checked in to Greenfield Farm, Kilkenny, but of course that can change very quickly at this time of the year. Official due date is not until 7 February.

Last week, I mentioned dry cow minerals and someone enquired if we had ever fed CalMag before calving to dry cows.

The answer is yes and I know many other farmers that have also.

Many farmers think CalMag is calcium but remember it’s magnesium. Calcined magnesite, commonly known as CalMag, is produced from the raw material magnesium oxide.

Nutrients

Why is it fed? In an effort to build soil nutrients we have spread a lot of potassium on silage ground and as a result some years we have had very high potash in silage.

High potassium can tie up magnesium. Milk fever is a common condition, predominantly occurring around calving time, and refers to a state of low blood calcium. If blood calcium levels are extremely low, clinical milk fever will be seen.

However, this should be seen as a warning sign for a larger problem as it is likely that there are many more animals on the farm with subclinical hypocalcaemia, ie sub-normal blood calcium, which will have knock-on effects on feed intake, disease and fertility.

Susceptible

Older cows tend to be more susceptible to milk fever as they have decreased ability to mobilise calcium from their bones. Fat animals are also more susceptible to milk fever.

Do three things if milk fever is a challenge now as calving starts:

  • Make sure dry cows are not getting over fat (especially March calvers).
  • Make sure dry cow minerals are going in and CalMag before calving might work.
  • If feeding dry minerals or CalMag before calving, you have to feed twice a day to ensure all cows have a chance.
  • As explained previously the first of the urea has been spread at €380/t list price.

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    Calving just about to kick off in Kilkenny