Vigilance as a measure of fear in dairy cattle

Abstract

Wild animals increase vigilance at the expense of feeding time in response to predation risk or threats from conspecifics. Increased vigilance may therefore indicate increased fear. We tested dairy cattle to determine whether time spent vigilant changed in response to the novelty of their location, the presence of a dog or the presence of an aversive, gentle or unfamiliar handler. We conducted 12 3 min trials per cow on 40 cows tested individually in a large outdoor enclosure containing an attractive food source. The feeders restricted the animal’s view so that it could not feed and scan simultaneously, so vigilance time was defined as any time the animal’s head was raised. During the initial trials, the degree of vigilance was high, but the amount of vigilance decreased significantly with number of trials. Time vigilant was significantly higher in the presence of a dog than in the presence of a human or when neither was present. In a second experiment, 20 cows, that had been trained to recognise an aversive and a gentle person for 3 weeks prior to testing, were tested in an indoor pen containing an attractive food source with the aversive, gentle, or an unfamiliar person nearby. The presence of the aversive person significantly increased vigilance time compared to the unfamiliar and gentle people. However, vigilance time did not decrease with repeated exposure to the enclosure, perhaps because the testing barn was already familiar. These results suggest that cows alter their vigilance according to their degree of fearfulness toward people and toward different environments, and that measures of vigilance may provide information on the degree of fearfulness of the animals.