Development of validated cognitive and behavioural indicators of welfare in pigs towards a predictive early warning system for poor welfare.

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Statistics, physics, engineering and psychology utilise a wide-range of methods that can be adapted for use as animal-based welfare measures if only they could be validated in a model animal system. Validated indicators could then be used to develop a predictive early warning system so that potential welfare problems can be detected and mitigated in advance. Previous research has shown pigs to be an ideal model system for such a project, showing significant welfare improvements when provided with enrichment, and extent of skin injuries sustained reliably indicating welfare state. In this study, categories of pigs of different welfare status will be created using both physical and environmental factors to develop and validate novel welfare indicators, based methods used in statistics, physics, engineering and psychology. Large White x Landrace pigs will be kept in groups of 20 in one of two environmental conditions: (1) deep straw pen, and (2) part-slatted floor. A total of 800 pigs (10 batches of 4 groups of 20) will be observed for 6 week periods. CCTV video cameras will record the pens for 12 hours per day once a week throughout the experiment. Every pig will be individually marked so that they are identifiable from the camera. At intervals over the first 4 weeks, each pig will be assessed and given a 'welfare' score based on measures of injury (to body and tail separately). The 4 pigs from each pen with the highest average % body injury score will be the 'Low welfare' group and the 4 with the lowest average % score will be the 'High welfare' group. This will give four groups: (a) High welfare on deep straw; (b) High welfare on part-slatted floor; (c) Low welfare on deep straw; (d) Low welfare on part-slatted floor. Before each trial starts, 5 pigs will be selected at random from each pen and will be trained and tested throughout the trial using 3 cognitive behaviour tests: cognitive bias (to determine the individual's level of optimism or pessimism), functional memory (to assess how well individuals can keep track of a pattern) and interval timing (to determine the perceived passage of time by different individuals). Cognitive bias has been shown to be affected by the welfare state of the animal. Functional memory and interval timing have not been utilised in animal welfare studies; this project will aim to validate these methods as new useful tools to assessing the impact of welfare on cognitive processing. In addition, the 4 pigs with the highest and lowest % injury from each pen will be tested using the three cognitive behaviour tests at the end of the trial. We will also record acoustic communication both within a pen and of selected individuals within a pen. From the recorded video footage, each of the focal pigs will be retrospectively tracked and their behaviours recorded for differences in individual activity budgets over the course of the trial. In addition, a number of tools will be used to investigate the social group dynamics within each pen. Fractal analysis of movement and semi-hidden Markov-chain analysis will identify repeating sequences of behaviour, social network analysis will determine the relative positions of each pig within its pen network and the overall level of connectedness within the group, levels of clustering will be assessed to determine whether individuals in a pen are crowding together more than expected given the space available to them, and finally we will assess the levels of synchronous behaviour within each pen. We will analyse each of indicator to look for differences between the 4 stated group types. Finally, a predictive statistical tool will be developed based on the entire data set, which can be used as an early warning system for welfare problems. The aim of the predictive model will be to predict which pens and which individuals within them, are likely to develop welfare problems at a later stage and hence permit mitigation strategies to be put in place.