Abstract Evidence that 5-min contact with a calf immediately post partum is sufficient for the formation of a strong, specific maternal bond with that calf is presented. Using a choice of two calves as a basis, it was found that this bond lasts, even if the calf is removed for 12 h and then returned. After 24 h of separation the cow still shows signs of distress but can no longer recognize her own calf. If no contact is allowed between mother and young for periods of up to 5 h post partum, this maternal bond is not formed in 50% of the animals. The results suggest that there is a sensitive period for the development of maternal responsiveness in dairy cattle.