The susceptibility to body strike under high rainfall conditions of flocks selected for and against fleece rot

Abstract

The susceptibility of Merino sheep to fleece rot and body strike was examined in a high risk environment. The ewes were a representative sample from 2 selection lines selected solely for increased (susceptible) and decreased (resistant) expression of hogget fleece rot in a low risk environment with the aid of induced fleece rot. A total of 244 fleece rot and body strike observations were made over 3 years. Ewes from the resistant flock had significantly fewer fleece rot lesions (P<0.05) of less severity (P<0.01) than ewes from the susceptible flock. The prevalence of body strike was high in all 3 years, with 11.3% affected in the resistant flock and 20.0% in the susceptible flock. The prevalence of fleece rot lesions was strongly correlated (P<0.001) with the prevalence of body strike. Results confirm the close phenotypic and genetic relationship between resistance to fleece rot and body strike, and show the potential of selection for reduced fleece rot in a dry environment to improve resistance to body strike in a wet environment.