A survey of post-weaning mortality of sheep in Australia and its association with farm and management factors
Angus J. D. Campbell A F , Annefleur Broekhuizen B , Kimbal Curtis C , Keith P. Croker C , Ralph Behrendt D and Andrew N. Thompson C EA Mackinnon Project, Faculty of Veterinary Science, University of Melbourne, 250 Princes Highway, Werribee, Vic. 3030, Australia.
B Quantitative Veterinary Epidemiology Department, Wageningen University and Research Centre, Wageningen, the Netherlands.
C Department of Agriculture and Food Western Australia, 3 Baron Hay Court, South Perth, WA 6151, Australia.
D Department of Environment and Primary Industries Victoria, Hamilton, Vic. 3300, Australia.
E School of Veterinary and Life Sciences, Murdoch University, 90 South Street, Murdoch, WA 6150, Australia.
F Corresponding author. Email: a.campbell@unimelb.edu.au
Animal Production Science 54(6) 783-790 https://doi.org/10.1071/AN13149
Submitted: 16 April 2013 Accepted: 6 August 2013 Published: 24 September 2013
Abstract
A cross-sectional telephone survey of post-weaning sheep management and mortality was conducted involving 1410 farmers from across Australia. The average reported post-weaning mortality was 4.6%. Mortality was greatest in Queensland and Western Australia, and least in New South Wales, Victoria, and South Australia. Weaner mortality was also greater in the pastoral zone than in the sheep–cereals or high-rainfall zones. Overall, 44% of farms had mortality identified as ‘high’, exceeding the suggested benchmark of ≤4% per annum. High mortality was reported on 50% and 32% of farms with predominantly Merino and crossbred weaners, respectively. There was no statistically significant association between high mortality and the main month of lambing for a flock. Larger sheep flocks, flocks with a smaller proportion of weaners, and farms of smaller area were associated with a greater likelihood of high weaner mortality. The odds of high mortality in weaner flocks that were routinely separated according to bodyweight or condition score was half that of flocks that were managed as one group. Overall, 84% of farmers regularly provided supplementary feed to weaner sheep, but the kind of supplement offered and the proportions of farms routinely supplementing differed between states and sheep production zones. Only high-protein supplementary feeding was associated with lower odds of high mortality. This survey confirms that poor post-weaning survival remains a widespread issue for the Australian sheep industry but identifies farm and management factors associated with reduced weaner mortality.
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