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Title: Equine obesity : linking predictions from evolutionary biology with the ingestive behaviour and subsequent body condition of UK horses and ponies
Author: Giles, Sarah Louise
ISNI:       0000 0004 5917 1103
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2014
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This thesis assessed the factors influencing body condition and subsequent obesity risk in UK horses and ponies, using an interdisciplinary approach. It was novel in considering social and behavioural risk factors for obesity, using modelling to generate testable predictions, epidemiological risk factor studies to quantify the relative role of behavioural versus other factors, and behavioural fieldwork studies to support model predictions. In a partially outdoor-living population the prevalence of obesity was 27% at the end of winter, rising to 35% during summer. Regional nuchal crest adiposity had the opposite seasonal pattern. Breed was the most important factor in determining obesity risk. As horses and ponies became obese, usual seasonal variation in body condition was reduced, something not previously reported. The role of social and behavioural risk factors in determining body condition and subsequent obesity was highlighted. Dominance was strongly associated with body condition in two studies, where more dominant individuals tended to have a higher body condition score and greater obesity risk. Theoretical modelling predicted that differences in foraging efficiency could lead to stable and predictable body condition differences within pairs and trios of individuals. When tested empirically, foraging efficiency was associated with both dominance and body condition in domestic herds. Animals with a greater foraging efficiency generally had a higher body condition and were more dominant. A potential 'fattening cycle' is described whereby a greater body condition leads to a higher dominance status, allowing for a greater foraging efficiency, and further body condition increase. Herd dynamics and social relationships could therefore determine obesity risk. The direction of association between dominance, body condition and foraging efficiency requires future longitudinal investigation. Social and behavioural risk factors should be considered in future clinical investigations in group-living animals. A series of practical recommendations for horse owners are detailed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available