The Moocall calving sensor is the best tool a farmer can have in their arsenal at calving time.

However, if this farmer doesn’t know how to use it, it will be of limited value to them.

Timing is key when it comes to attaching your moocall sensor. The sweet spot most users have found is around 3-4 days before calving.

You shouldn’t attach your Moocall any more than 10 days prior to the the due date.

However that depends on the accuracy of your birth records.

Moocall Calving Sensor Waco Mobile Vet

After 4 days of having the sensor on the tail of your pregnant cow, she will need a break for an hour or two.

You don’t want to be caught in one of these blind spots so be vigilant during the hours your cow hasn’t got it on.

Most people judge whether they should attach the calving sensor on physical signs of calving.

Pins Drop

If a cow has her ‘bones loose’, aka, if the pin bone ligaments on either side of the tail on her upper pelvis relax, then she is getting close to calving.


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Because of this the tailhead could appear to stick up and it will appear loose/relaxed when the animal walks.

Just to note, on beef cows or fat cows it will be much harder to use the ligaments as a determining sign.

Bagging up

Another sign to look for is the cow ‘bagging up’, or having her udder full of milk.

This doesn’t suggest that calving is imminent but it does happen anywhere from a week out from calving.

This can depend on breed – dairy cows are almost permanently bagged up.



Springing, aka a cows vulva becoming swollen, is a telltale sign that calving will start soon.

The vulva will appear loose, floppy and swollen.


If you attach the sensor too tight, you may end up getting false alarms from your cow. If you attach it too loosely, it could end up falling off.

This is where the new red rubber for the calving sensor comes in handy. In comparison to the grey rubber we used before, it leads to much fewer false alarms and instances of devices falling off tails.