Genetic Analysis of Flystrike in Sheep

Abstract

Flystrike in sheep is a parasitic disease where eggs or larvae are deposited onto the host and is predominantly caused by the sheep blowfly 'Lucilia cuprina'. Flystrike can cause production losses, chronic disease and death in sheep. There are many predisposing factors which contribute to flystrike occurring and these include: environment, management and physical attributes of the sheep. Flystrike is estimated to be the fifth largest cost to the Australian sheep industry, with breech strike identified as the most significant type of flystrike. Various management practices are used to control breech strike, including mulesing, shearing and chemical application. Increasing pressure from animal welfare groups and consumer resistance to purchase wool products derived from mulesed sheep has contributed to identifying alternative methods to control breech strike. One alternative method is breeding sheep resistant to breech strike. As the expression of flystrike is environment dependent, and direct selection is ethically and economically undesirable, indicator traits which can be used for indirect selection offers an alternative method to breed for resistance to breech strike.