Gut parasitism is a major problem for sheep farming.  It has been estimated that upto 30% of modern sheep production is reliant on effective parasite control.  The shift from wool production to lamb production, and increasing intensification, are all increasing the pressure of worms on the farming system. 

Unfortunately chemical control of worms (drenching) is deteriorating rapidly with the spread of multiple drench resistant worms through sheep flocks.  Triple drench resistance in worms is now not uncommon and although “new actives” are available they are much more expensive and will only have a limited life before resistance get to them as well.  The only sustainable solutions are through management, and worm resistant sheep is a major tool for this.

We know that there is a genetic component to resistance, so it can be selected for.  As with all genetic traits the rate of progress depends on a number of

factors including, how long you have been selecting for this trait and how serious you are about it (how much emphasis you put on this trait as opposed at all the other traits that you are selecting for). 

When selecting a breeder you need to ask the hard questions about when they started selecting, how they are selecting and what future plans do they have.  A group of ram breeders who are serious about selecting for parasite resistance have formed WormFEC Gold. WormFEC gold members have a track record and a passion and the knowledge to produce rams with a genuine genetic advantage.  Remember however that using one “resistant” ram will not suddenly mean that you do not have to drench the lambs.  This is a long project with incremental gains but one that could ultimately keep you able to farm sheep profitably.