Effective grazing management reduces the exposure of sheep to worms. There are three methods:
Weaners and hoggets are the class of sheep most susceptible to worms, especially when they go through their second winter as hoggets. Paddocks used by young sheep in late autumn and winter should be of the highest quality pasture as the first priority, ideally they should also be of low worm-risk. Pastures grazed after the autumn break (before the ‘hogget winter’) should be the lowest worm-risk on the farm. This will give hoggets a good start, in many cases allowing them to build immunity without suffering high initial worm burdens.
On winter hogget paddocks most contamination occurs in late summer and autumn.
Lambing ewes are the next most susceptible group, as they temporarily lose some of their immunity to worms at and after lambing. As a result, they contribute to the seasonal increase in worm numbers and subsequent infection of lambs.
The following practices to prepare or choose low worm-risk paddocks are most important in the South-East and Higher Rainfall Mediterranean zones, but can also be used in the Lower Rainfall Mediterranean zone.
The following practices or a combination of these can create paddocks with less worm contamination and lower worm-risk:
Choose the least contaminated lambing paddocks for the most susceptible lambing ewes (maidens, oldest ewes and earlier lambing ewes). Base this on results from WormTests from these paddocks over the last 6 months.