Risk factors for Merino ewe mortality on the Northern Tablelands of New South Wales, Australia

Title
Risk factors for Merino ewe mortality on the Northern Tablelands of New South Wales, Australia
Publication Date
2014
Author(s)
Kelly, Gareth A
Kahn, Lewis
( author )
OrcID: https://orcid.org/0000-0002-3679-4530
Email: lkahn3@une.edu.au
UNE Id une-id:lkahn3
Walkden-Brown, Steve W
( author )
OrcID: https://orcid.org/0000-0002-0638-5533
Email: swalkden@une.edu.au
UNE Id une-id:swalkden
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
Wiley-Blackwell Publishing Ltd
Place of publication
United Kingdom
DOI
10.1111/avj.12145
UNE publication id
une:17940
Abstract
Objective: To measure the association of worm egg count (WEC), body weight (BW) and fat score (FS) with mortality in Merino ewes. Methods: On six farms, Merino ewes (n = 1440) were yarded at approximately 3-month intervals for 2 years for a range of experimental measurements. Mortality was defined by failure to present at two consecutive measurement days and at next shearing. Survival analysis was conducted with phenotypic traits measured both as continuous variables and categorised appropriately for industry guidelines. Results: Overall mortality was 10%, with most deaths occurring in autumn followed by winter. Age class (2006 drop vs mature-age ewes) did not affect mortality. High WEC, low BW and low FS significantly increased the risk of mortality. WEC > 1200 epg significantly increased risk of mortality in summer (risk ratio 3.76) and autumn (risk ratio 3.61) compared with the reference group. Risk of mortality increased 1.1-fold for each kilogram unit decrease in BW and 7-fold for each unit decrease in FS. Conclusions: Mortality of Merino ewes can be significantly reduced by management methods that reduce WEC, maintain BW and increase the FS. For Merino ewes on the Northern Tablelands of NSW, improved animal welfare and economic benefits may be achieved by maintaining sheep with WEC < 1200 epg, BW > 35kg and FS > 2.5.
Link
Citation
Australian Veterinary Journal, 92(3), p. 58-61
ISSN
1751-0813
0005-0423
Start page
58
End page
61

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