Nickers of horses as indicators of a positive affective state?
Summary
Abstract
In this pilot-study animal welfare is stated as a balance between positive and negative experiences. This balance may range from good to poor welfare. Many ways have yet developed to assess animal welfare; however, most of these methods are based on negative emotions and are contradictory or invasive. There is an increasing need for tools to assess animal welfare in an easy and non-invasive manner that is based on positive emotions. One of these tools is reward sensitivity. Anticipatory activity is expressed as hyperactive behaviour. Anticipating animals show an increase in activities, vocalizations might be one of them.
For animals, vocalizations are a way to communicate. Vocalizations are expressions of a distinct inner state of an animal and can contain information of the emotional state of an animal.
Much research has already been done on vocalizations during positive anticipation of animals, for example rats. Yet, we don’t know much of vocalizations of other species, like horses. Kiley (1972) and Waring (1983) described nickers of horses as vocalizations emitted prior to feeding and are suggested to announce anticipation (Waring, 1983: 283-300).
In this pilot-study positive vocalizations of horses that could indicate a positive affective state are being investigated. The aim of this pilot-study was to see if nickers are indeed emitted during positive anticipation. These vocalizations could then be an indicator of a positive affective state and might be used as a tool to assess animal welfare.
There will also be examined how horse vocalizations can be recorded in such a way that they are useful for bio acoustic sound analysis. Also, the context in which nickers are emitted will be investigated. The recorded nickers will be bio acoustically analysed to give a detailed description of nickers, to reveal parameters that could indicate the intensity of the emotion, and, when possible, to look for individual characteristics.
There were two experiments set up in this pilot-study: The “positive anticipation experiment” and the “context experiment”. Both experiments took place at horses’ stables.
In the first experiment horses were trained to anticipate for pieces of carrot. One horse emitted nickers during the anticipatory period, in the rest of the test group and the control group, no nickers were emitted. So, nickers were emitted during anticipation for food; however, they could not be related to positive anticipation. This was because no correlation could be made between the anticipatory behaviour and the nickers, since the data on anticipatory behaviour was not obtainable yet. However, the vocalization pattern of the vocalizing horse did support the expectation that nickers are emitted during positive anticipation. Furthermore, it was possible to give a detailed description of the nickers of the one horse that vocalized. No parameters were found that could be an indicator for the intensity of emotion. Based on this data, no conclusions could be drawn if nickers are indicators of a positive affective state.
In the second experiment, the “context experiment”, the context in which nickers are emitted were investigated. Therefore, 5 situations were created and recorded; control, human, carrot, silage, and concentrate. Significant more nickers were emitted when the horses were fed silage and concentrate, only one horse emitted nickers during the carrot test, and least nickers were emitted during human and control. There can be concluded that nickers are related to the context of food, and there is no indication that they are emitted to attract human social attention. However, whether nickers are also emitted when other positive stimuli are present, cannot be ruled out and requires further investigation. Due to background noise in this environment, no analysis could be done on the vocalizations and so no parameters that could be an indicator of the emotional state of a horse could be found.
In both experiments, no conclusions could be drawn about individual characteristics of nickers, because in the “positive anticipation experiment” there was only one horse that emitted nickers, and in the “context experiment” the recordings were of such low quality due to background noise, that they could not be used for bio acoustic analysis.
Finally, whether nickers could be tool to measure a horse’s welfare or not, cannot be concluded in this pilot-study, and requires further investigation.
Another aim of this pilot-study was to look for the best recording techniques. Sound tests indicated that the directional MKH 416T Sennheiser microphone is best suited in these environments. Furthermore, there can be concluded from the data that was obtained from the two experiments, that horses’ stables are not the suited environment to record horse vocalizations.