Power of the draft

Last week we drenched our young ram and ewe lambs, as they were showing signs of brown scour worm and needed prompt attention. While we were drenching, it occurred to me how much genetic progress could be made towards worm resistance in the flock, by the power of the draft gate. Not all the lambs showed signs of worm and were still gaining weight, others had dirty back ends. If we drafted all the dirty bums out, and checked their parentage, we would start to build a picture of worm susceptibility in our various family lines. A useful start before looking into genetic testing. We have finally reached the numbers in the stud flock to begin refining them on qualities other than phenotype.
A useful resource for worms is http://www.wool.com/Grow_WormBoss.htm