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Food, fibre and pharmaceuticals from animals
RESEARCH ARTICLE

Sheep category can be classified using machine learning techniques applied to fatty acid profiles derivatised as trimethylsilyl esters

P. J. Watkins A B C F G , D. Clifford D , G. Rose B , D. Allen B , R. D. Warner A B , F. R. Dunshea A E and D. W. Pethick A C
+ Author Affiliations
- Author Affiliations

A Cooperative Research Centre for Sheep Industry Innovation, CJ Hawkins Homestead, University of New England, Armidale, NSW 2351, Australia.

B Department of Primary Industries, 600 and 621 Sneydes Road, Werribee, Vic. 3030, Australia.

C School of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, WA 6150, Australia.

D CSIRO Mathematics, Informatics and Statistics, Locked Bag 17, North Ryde, NSW 1670, Australia.

E Melbourne School of Land and Environment, University of Melbourne, Parkville, Vic. 3051, Australia.

F Present address: CSIRO Food and Nutritional Sciences, Private Bag 16, Werribee, Vic. 3030, Australia.

G Corresponding author. Email: peter.watkins@csiro.au

Animal Production Science 50(8) 782-791 https://doi.org/10.1071/AN10034
Submitted: 24 February 2010  Accepted: 10 June 2010   Published: 31 August 2010

Abstract

Eruption of permanent incisors (dentition) is used as a proxy for age for defining meat quality in Australian sheep meat. However, this approach may not be reliable. While not presently available, an objective method could be used to determine sheep age, and thus sheep category, which would then potentially remove any inaccuracies that may occur in classifying sheep meat product. Statistical classification algorithms have been successfully used in bioinformatics. In this paper we review the performance of three algorithms (support vector machines, recursive partitioning and random forests) for determining sheep age. The algorithms were applied to the measured fatty acid profiles of fat samples from 533 carcasses; 254 lamb (<1 year old), 131 hogget (~1–2 years old) and 148 mutton (>2 years old) samples. Three data pretreatments (range transformation, column mean centering and range transformation with mean centering) were also examined to determine their impact on the performance of the algorithms. The random forests algorithm, when applied to mean-centred data, gave 100% predictive accuracy when classifying sheep category. This approach could be used for the development of an objective test for determining sheep age and category.


Acknowledgements

This work was funded by the Cooperative Research Centre for Sheep Industry Innovation and this is gratefully acknowledged. We are grateful to Jan Gerretzen and Tom Bloemberg, of Radboud University in The Netherlands, for making an early version of the PTW package available to us. We are also grateful to Alec Zwart of CSIRO Mathematics, Informatics and Statistics, who made useful comments on the paper.


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