Heat detection systems involving activity monitoring present too many false positives.
On a farm call to county Cork today with a large dairy herd encompassing both dairy cows and maiden heifers for smart scan. On this farm heat detection system involving activity monitoring using collars on the cows to identify cows for AI in both dairy cows and maiden heifers with the primary mode of heat detection. Smart scan today revealed almost 15% of cows being presented for AI were not in heat. Indeed, cows were being presented for AI while pregnant, in the middle of their heat cycle and in addition, smart scan revealed that there were cows that had been in heat the previous week and had failed to be detected by the heat detection system.
Heat detection systems involving activity monitoring with a pedometer are an aid to heat detection but unfortunately, they should not be relied on totally. It is essential that visual aids or in addition the use of either tail chalk scratch cards are used as a supporting aid to accurately define cows that are in heat.