In the present study the hypothesis that fear of humans is long-lasting and may influence milk production in Holstein cows was tested. One person (the aversive handler) carried out two daily sessions of an aversive treatment during 21 days, where each cow received two slaps on the rump and a strong yell. The control handler walked around the cows not menacing the cows. Flight distance from both handlers was measured before the treatments were imposed and 14 and 180 days later. Total and residual milk (measured after an i.v. oxytocin injection in the caudal vein) were measured when either the aversive or the neutral handler carried out the milking, between days 14 and 24 of the experiment. All the cows were used in both treatments in a cross-over design. Except for the day before treatments started, the cows kept a larger distance from the aversive than from the neutral handler, even after 180 days without contact with these handlers. Nevertheless, there was no effect of treatment on total milk yield or residual milk. The results corroborate others that show that cows can discriminate between aversive and neutral individuals. Under the conditions of the present study, the fact that milking was done by the aversive individual did not influence total milk yield and residual milk.
bovine; ethology; animal welfare; human-animal interactions; fear
