Associative learning by cattle to enable effective and ethical virtual fences

Abstract

An ability of cattle to readily associate a non-aversive audio cue (conditioned stimulus) with an aversive but non-noxious electric shock (unconditioned stimulus) should enable virtual fences to control cattle in an ethical manner similar to conventional electric fencing. The first study was conducted to identify an effective audio cue. Audio (784 Hz tone) and shock (600 V, 250 mW) stimuli were delivered by remote control to GPS collars on five heifers to prevent access to an exclusion zone surrounding a feed trough. An audio cue was administered when the animal entered the exclusion zone, followed by a shock if the animal continued to proceed. There was an increase in the proportion of heifers responding favourably to the audio cue by turning, backing up or stopping in sessions 3 and 4 (73%) compared with sessions 1 and 2 (44%). This indicated that cattle associated the audio cue with the electric shock and learnt to avoid the trough. The main study examined whether cattle location can be controlled by an audio conditioned stimulus without the presence of a visual cue. Weeks 1 and 2 tested heifers’ learning of the association between an audio conditioned stimulus and an electric shock reinforcer. In week 3, the effect of dispensing with the conditioned stimulus was tested. Heifers were allocated to two treatments ( n = 11). Treatment 1 received an audio cue and an electric shock on exclusion zone entry, as in the first 2 weeks. Treatment 2 received no audio cue and only an electric shock on exclusion zone entry. There was a difference in the behaviours shown in response to both the audio and shock stimuli between weeks 1 and 2, with more heifers turning in response to the audio cue in week 2 than in week 1. When the virtual fence was moved in week 2, 80% of animals ignored the first audio cue, but the proportion failing to respond to the second audio dropped to 46%, indicating that animals had learnt to avoid the electric shock by responding to the audio cue alone to remain within the virtual fence boundary. In week 3, heifers received significantly fewer shocks when a conditioned stimulus was used. There were no differences between treatments in scores for effectiveness of the fence, appropriateness of the stimulus and adverse responses. This study demonstrates that the appropriate use of an audio cue is an effective conditioned stimulus for virtual fencing of cattle.