Animal Production Science Animal Production Science Society
Food, fibre and pharmaceuticals from animals
RESEARCH ARTICLE

Sheep death and loss of production associated with flystrike in mature Merino and crossbred ewes

B. J. Horton A B E , R. Corkrey A C and A. K. Doughty A D
+ Author Affiliations
- Author Affiliations

A CRC for Sheep Industry Innovation, Armidale, NSW 2350, Australia.

B Tasmanian Institute of Agriculture, University of Tasmania, Launceston, Tas. 7250, Australia.

C Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tas. 7005, Australia.

D University of New England, Armidale, NSW 2350, Australia.

E Corresponding author. Email: brian.horton@utas.edu.au

Animal Production Science - https://doi.org/10.1071/AN16153
Submitted: 11 March 2016  Accepted: 6 January 2017   Published online: 28 February 2017

Abstract

In eight well-managed Australian Merino and crossbred sheep flocks the adult ewes were monitored frequently for flystrike. Occurrences of flystrike and severity of strike scores were recorded, whereas bodyweights and condition scores were recorded regularly across two wool production and reproduction cycles. In these unmulesed flocks, 17% of Merino and 5% of crossbred ewes were struck, with 2% of those struck dead within 7 days of detection of the strike. For those adult ewes that survived the immediate period of the strike, the rate of loss over the following year was slightly greater than for ewes that were never struck, particularly for those with a high severity strike. Flystrike also contributed to losses of up to 2.7 (Merino ewes) and 5.2 (crossbred ewes) kg of bodyweight, and 0.3 condition score units at the time of the strike. Bodyweights were still 2 kg lower by 3 months after the strike occurred for Merinos, although condition scores returned to average levels. For ewes struck between mating and lambing, flystrike was associated with significant losses of lambs. Flystrike at severity level 1 (light) had only minor effects on wool production, but severity score 3 (heavy) reduced clean fleece weight.

Additional keywords: body strike, mortality, reproduction, sheep blowfly, wool.


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