Slow milking cows are keeping farmers in the pit for up to 10 hours extra a year.
Data compiled from the milk recording of more than 10,000 cows showed that the difference between slow and fast milking cows was often as high as one minute per cow.
When multiplied up over a typical 300-day lactation, this equates to at least 10 hours extra time in the milking parlour for the farmer.
As a result, the latest dairy bull proofs now include scores for milking speed, along with other new traits such as temperament, mastitis and lameness. ICBF researchers were careful to ensure that the measurement of milking speed took account of milk yield, in order to avoid a scenario where lower yielding cows would be rewarded for having shorter milking speeds.
They concluded that the heritability of milking speeds had no correlation with milk yield or udder health.
As a result, it is one of the latest traits that has been incorporated into the EBI index.
Along with management traits such as temperament and health traits such as mastitis and lameness, the new sub-indexes account for 8pc of a bull's overall score.