Body condition scoring of sheep: intra- and inter-observer variability

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New Zealand Society of Animal Production (INC)
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Body condition scoring (BCS) is a hands-on tool that farmers can use to make decisions about their animal feeding and management. BCS, however, is a subjective measure of the muscle and fat cover of the lumbar spine. Observers, therefore, may show variability in scores both across time and from other observers. This study aimed to determine the intra- and inter-observer variation of both farmers and research technicians as part of a learning exercise of a farmer-learning group based at Massey University between 2011 and 2015. Nineteen farmers and three research technicians condition scored 45 mixed-age ewes on two consecutive days. Data from both farmers and technicians were analysed to determine the intra- and inter-observer variability using a weighted kappa. The results indicate that the majority of farmers and technicians had ‘excellent’ agreement (21 of the 22 observers had kappa values greater than 0.75) between days. Similarly, among pairs of observers the agreement was also ‘excellent’ (212 of 231 comparisons had kappa values greater than 0.75). The distribution of scores that contributed to each median condition score, however, indicated that lower scores (1, 1.5 and 2) has less variability than did higher scores (2.5 or greater). These results suggest that BCS is a robust farm-management tool that can be used with a high degree of repeatability. Keywords: body condition scoring; intra-observer variability, inter-observer variability.
body condition scoring, intra observer variability, inter observer variability
New Zealand Journal of Animal Science and Production, 2020, 80 pp. 107 - 112 (6)