Incorporating the data into a selection index improves the ease of selecting animals which are known performers in terms of clean fleece weights and fibre diameter. After worm resistant rams are selected the next step is to use them as breeders to increase the overall level of resistance in the flock. An alternative is to look for another ram source that provides the required information. Progress toward worm resistant flocks will only occur if producers use rams with a level of resistance better than their own flock mean. This will provide a measure of the success of the Nemesis programme.
Monitoring is now the heart of most worm control programmes.
The level of monitoring required varies on different farms but with young sheep a faecal egg count is best carried out several times a year. Despite the development of worm resistant sheep, drenching is still required but the number of drenches is expected to decline as selection proceeds. Prolonging the effective life of drenches is a major priority for the wool industry. Every time a worm strain becomes resistant to a drench more money is required to invest in the development of alternative control measures. It is worth taking an integrated approach to controlling internal parasites to prolong the effectiveness of existing drenches and increase their useful life.