Lambs (and ewes) should be checked for worm infestations with a worm egg count just prior to lamb marking. Lambs generally do not require drenching at lamb marking, unless a preventative drench for barbers pole worm is required.

Lambs are likely to require drenching at weaning, unless in low-rainfall pastoral areas. The need for a weaning drench (as shown by a worm egg count) is influenced by how well the ewes have been managed for worms. If the lambing paddock was well prepared and effective worm management strategies put in place, the lambs will have little if any worm burden.

Lambs and weaners are the sheep most susceptible to worms. Their immune systems have not yet started to function well.

Nutrition has a big effect on how well their immunity develops and how well they cope with worms. Low worm risk paddocks should be prepared for lambing and weaning months in advance. This can be done using 'smart grazing' or cross grazing with cattle.