文摘
In animal welfare science there is a strong need for objective parameters for the assessment of animal welfare. Anticipatory behaviour is a potential indicator of welfare since it reflects reward-sensitivity which is in its turn related to previous experiences of animals: negative experiences are positively correlated with reward-sensitivity and vice versa. In rats and several other species, anticipatory behaviour is reported to be characterized by an increase in activity. As a first step for future use of anticipatory behaviour as a welfare indicator in horses, the aim of this research was to characterize the equine anticipatory response to a reward. Both behaviours and parameters on autonomic heart rate (HR) and heart rate variability (HRV) have been measured in order to provide a full characterization of the anticipatory response. Anticipatory behaviours, HR and HRV of 13 horses were recorded in two separate experiments: 1. Before arrival of concentrate feeding during their normal daily routine and 2. During a standardized experimental set-up in which anticipation was evoked by means of a conditioning paradigm. Thus, in the first experiment the already existing anticipatory behaviour was investigated, whereas in the second experiment a new association between an unconditioned and conditioned stimulus was induced. An extensive ethogram was used to score all behaviours, afterwards behavioural elements were grouped in four different categories i.e. maintenance behaviour, standing, locomotion, and arousal and investigation. It was apparent that equine anticipatory response could be characterized as an increase in activity together with an increase in heart rate. In addition, both frequency and duration of standing, locomotion and arousal and investigation were significantly increased, while a significant decrease in time spent on maintenance behaviour was shown during anticipation. The increase in activity during anticipation was not influenced by individual differences, i.e. expression of specific anticipatory behaviours in some horses. Since the main characteristic of anticipation is an increase in activity, reflected by the number of behavioural transitions, results of this study are promising for future research on anticipatory behaviour as an equine welfare indicator.
