Use of genetic resistance

It has been shown that some breeds of animal are less susceptible to worms than others. Thus indigenous fat-tailed sheep are often more resistant than exotic types. Where losses to helminths are difficult (or expensive) to control, the use of these animals can minimise the need for other control strategies. Using indigenous fat-tailed rams for crossing into an existing flock can produce not only an improved resistance to worms but also introduce the benefits of hybrid vigour and increased hardiness to other conditions.