This avoids a long 'tail' in the lamb flock, with small lambs at weaning remaining as the runts of this lamb drop. Worm control Life cycle of sheep worms Adult worms in the sheep's gut lay eggs which pass out in the droppings. Once on the pasture, and provided it is not too cold or too dry, the eggs hatch into first stage larvae within one or two days. Once inside the sheep the third stage larvae develop into adult egg-producing worms in about three weeks, and so the cycle continues. During winter, eggs and larvae are capable of surviving for several months on the pasture.
Egg production varies with the type of worm present.
Since the eggs of Nematodirus are capable of surviving for 12 months, lambing and weaning on the same paddock year after year can result in an accumulation of these worms. The lambing paddock Normally, adult dry sheep do not produce many eggs even if they have high worm burdens, because their acquired immunity suppresses the production of worm eggs. The immunity of the lambing or lactating ewe on the other hand is markedly reduced, therefore they can have a very high egg output. The lambing paddock very rapidly becomes highly contaminated. This is not a problem for the lamb until it begins to eat a significant amount of pasture.