Worm Control Options this Autumn

After a rain event it can take a couple of weeks for the sugars to re-establish in grass and it is also an opportunity for parasite larvae to re-emerge and have a chance to complete their life-cycle. With dewy mornings and warm day-time conditions internal parasites have much faster development to the infective stage (7 days from egg hatch to infective larvae) and much better egg hatch rate. In these conditions worm control in lambs/hoggets, 2 tooths and lighter mixed age ewes is beneficial. For the most part an effective combination oral drench is sufficient.

For lambs drench interval needs to be every 28-30 days. DON’T LET YOUR DRENCH INTERVAL SNEAK OUT TO 5 WEEKS+ unless you monitor with an egg count. The worm burden on the ground can ramp up very quickly when drench intervals are stretched out and mobs are set stocked. If lamb feed has become “wormy” (e.g. under irrigation or constant lamb grazing since January) then persistent acting drenches can get your lambs out of a parasite rut. Trimox oral, Exodus or cydectin LA, capsules are options. For fine wool lamb traders long injectable drench is very appealing to keep them going well through the autumn.

New product just released is Bionic Plus Hogget for lambs 20-40kg. They are similar to a standard bionic capsule, just with the size and dose wound back. They will be most suited to fine wool lambs going through the winter, especially if on irrigation. Refugia is important I would recommend 50-100 undrenched ewes/mob to supply parasite turn-over without exposure to drench. Egg count monitoring at 60-80days essential.

Using a novel active drench on lambs/hoggets at some stage through March – May is recommended to clean out any resistant parasites that have accumulated. This practice is becoming mainstream as farmers realise we cannot keep hammering our existing drench families. Zolvix plus and Startect are the two options. Farms where certain drench resistance has been diagnosed then targeted use of novels on ewes pre-tup is advised (e.g. Startect to 2 tooths, light ewes).

In these conditions using adult cattle behind lambs, or ewes behind calves is a very good way of maintaining lower levels of parasite burdens through a “wormy autumn”.