Farmers who are interested to rear calves together with the dairy cows during the first weeks of life are confronted with problems of poor milk let-down during machine milking. Therefore it was investigated whether 3 calf-associated stimuli were capable to enhance milkability of the cows. In this contribution, the effect of the stimulations during milking on heart rate (HR) and agitation (rumination, posture of the head and behaviour during udder preparation)are presented. Olfactory (calf hair), tactile (teat massage) and acoustic(recorded calf calls)stimulation were tested on 15 dairy cows with permanent contact to their calves and 22 control cows. All cows were milked twice daily. Stimulation tests were conducted in 3 consecutive weeks during day 25–51 of lactation, each stimulus tested in 4 milkings versus 4 routine milkings. As HR was only measured at morning milkings there were only 2 repetitions per stimulus. Mixed models with the fixed factors stimulation (vs. routine milking), calf-contact, breed (German Red Pied vs. German Holstein) and parity (primiparous vs. pluriparous) and the random factor animal were applied for each parameter. Rumination and posture of the head were not influenced by any factor. Agitation behaviour and HR in the parlour were not affected by calf-contact. This questions stress as elicitor of problems with milk ejection. Tactile stimulation had an increasing, acoustic stimulation a decreasing effect on HR. German Red Pied showed more agitation behaviour during udder preparation and a higher HR in this phase compared to the German Holsteins. This could be due to differences in temperament or sensitivity to touching. According to expectations, primiparous cows showed more agitation during udder preparation than pluriparous, but this was not accompanied by an HR increase. The results did not indicate higher stress reactions in the parlour of dairy cows with calf contact. Acoustic stimulation led to a lower HR independent from calf-contact compared with HR at routine milking
