The effect of herd mentality on dairy heifers conditioned to traffic through audio cues

The objective for the present trial was to understand whether dairy heifers could be trained to respond to an audio cue paired with a feed reward. The use of acoustic conditioning to induce cattle movement has not previously been tested with animal-mounted devices to call cattle both individually and as a group. Five heifers underwent testing for 6 days as part of an 18-day field trial (12 days of conditioning). The 6-day testing and data-collection period involved the heifers being called via a smartphone device mounted on the cheek strap of a halter. Heifers were called either as individuals or as a group. When the audio cue was sent, heifers were expected to traffic from a group-holding area to a feeding area (~80-m distance) to receive an allocation of a grain-based concentrate. Heifers were significantly (P = 0.001) more likely to approach the feeding area when called as a group (91% response rate) than when they were called as individuals (67% response rate). When heifers did respond to being called, their time to traffic to the feed area was quicker (P < 0.001) when they were called as a group (77.9 ± 55.4 s) than when they were called as individuals (139.3 ± 89.2 s). The present trial has shown that animals can be trained to respond to an audio cue paired to a feed reward, highlighting the potential for acoustic conditioning to improve voluntary cow movement with an animal-mounted device. It also highlights the limitations of cattle responding to being called individually compared with being called as a group.