||Fences are crucial for successful grazing management of livestock. However, conventional fencing is expensive and lacks spatial flexibility. To date, this flexibility has been provided by electric fences, but these are not always efficient to erect and move and are not suitable for all locations. The development of virtual fencing could improve flexibility, but implementations often incorporate electric shock as a means to deter animals from crossing a defined line. Alternative deterrent methods may be required due to legal requirements in some countries. Therefore, the aim of the study was to test "irritating" sounds from the sonic range (8 kHz and a mix of 8-10 kHz) in order to establish if they could discourage beef cows from spending time in a specific area. A third treatment using "acute alarming" sounds as a comparison was also tested.
In our study, we created a virtual fence by placing loudspeakers at 10 m intervals across a small paddock. There were six groups of test cows: three groups were tested in a first observation session and three groups in a second session each day. Testing took place over three consecutive weeks, with two control days and two test days per week. In each week each group was tested with one of the three sounds in one of three paddocks.
The results indicated that irritating sounds are as effective as acute alarming sounds at discouraging animals, but not sufficiently effective for commercial application when played from loudspeakers mounted on posts. However, a highly significant effect of the use of sounds was identified, showing that sounds can be used as adverse stimuli. Moreover, reduction in use of zones closest to the loudspeakers and increased use of zones furthest away from the loudspeakers during the sound tests strongly indicates that the use of sound can influence cattle location.
In synthesis, the study has shown that the use of irritating sounds as aversive stimuli is a valid and potential option for the development of virtual fencing. Although, it does not have exactly the same effect as a conventional fence in terms of stock-proofing, this technology can open up new possibilities in grazing management, especially when low grazing pressure is favourable. However, for commercial applications, further research is needed to investigate the use of animal-borne devices to broadcast sounds so that the dB level for the sound is kept at a consistent level.