Genetic research into the heritability of flystrike susceptibility in sheep, and its expression in different operating environments, is set to be incorporated into new tools to assist breeders make more informed selection and flock management decisions.
Tracie Bird-Gardiner, from the NSW Department of Primary Industries, has spent the last four years collecting and analysing data from fly-struck sheep in the industry’s Information Nucleus Flock (INF), under a postgraduate study scholarship provided by the Cooperative Research Centre for Sheep Industry Innovation (Sheep CRC).
Mrs Bird-Gardiner’s analysis has provided industry with a deeper understanding of the genetic heritability of flystrike resistance, including how to identify susceptible sheep using indirect markers, and how the trait responds to the environment and interacts with other genes that drive flock productivity.
Her findings are set to feature in an app under development by the Sheep CRC to assist producers to monitor the health and productivity of their flock, and predict when individual animals may be at risk from disease and weather events.
“My thesis focused mainly on breech strike data collected at the Trangie and Cowra INF sites, where conditions can result in longer periods of flystrike risk compared to the summer and winter dominant rainfall areas,” Mrs Bird-Gardiner said.
“The research identified potential indicator traits for breech strike which could be used for indirect selection in breeding breech strike-resistant sheep in a non-seasonal rainfall environment. For example, yearling breech wrinkle was identified as a key indicator trait for breech strike.
“Although selection for reduced breech strike and breech wrinkle was found to have a small unfavourable correlation with fleece weight, this can be taken into consideration when making selection decisions.
“The repeatability of susceptibility to breech strike was also evaluated and it was found that there is a fairly high likelihood that ewes struck at their first lambing are likely to be struck again in following years. It is therefore important for producers to carefully consider whether they want to keep these sheep in their breeding flock.”
Mrs Bird-Gardiner received her Masters degree at a graduation ceremony last week at the University of New England, Armidale. She chose flystrike as her research topic due to its importance for the sheep industry and its significance as an animal welfare issue. Flystrike is estimated to be the fifth largest cost to the Australian sheep industry.