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Victoria worms, flies and lice update - January 2021

VIC WormBoss Worm Control Programs

VIC WormBoss Drench Decision Guides

Sheep

Goats

Sheep

Goats

Hamilton: Lexie Leonard, Livestock Logic (l.leonard@livestocklogic.com.au)

Summer is yet to arrive it seems in the southwest of Victoria. There has been plentiful cool weather and rain events, which amongst other things means it has been a perfect growing season for worms. There have been a lot of very high worm egg counts (WEC) in the past three weeks, most have been mobs that were drenched in late November–early December and have not been monitored since.

Short green feed will be the source of major worm burden pickup in mobs since the start of January. As there have not been any stretches of hot weather to kill worm larvae on pasture, there will still be large amounts of infective larvae on pasture. Tall standing feed with short green pick underneath will also be a source of infection for stock, and standing feed provides excellent protection for larvae in pastures to survive. Looking forward, even with a few days of hot weather here and there we expect a lot of pasture larvae to survive well into February. This is important to keep in mind when planning paddock rotations. If you have had high WEC results in the previous year, it is likely the contamination remains high. Removing standing pasture by heavy grazing before a run of hot, dry weather to allow larvae to die (1,000 kg dry matter should be adequate) will help decrease surviving worm larvae.

I cannot stress enough the importance of continued WEC monitoring, especially if you have had a run of high WEC results since the end of November. It is not uncommon to see mobs spike high results after periods of rain or cooler weather, and mobs returning high WEC results 4–5 weeks after drenching. Weaner sheep and cattle mobs should be having a WEC every 3–4 weeks, and adult ewes every 4–5 weeks.

Flies are beginning to become more than a one-off issue as fly control wears off from November and the weather is (hopefully) warming up. Early and decisive fly control will help keep local fly populations low as well as minimize production loss. Always double check wool withholding periods and export slaughter intervals for any chemical you use, and consult with a veterinarian if you are changing dilutions or doses, as this will change the withholding periods for meat and wool.

With high WEC results come an opportunity to do a drench resistance test if you have not done one in the previous three years. Good drenching management cannot be done without knowing what you are working with, so updating your resistance results will help set up 2021 to be a great year for parasite control!

For January 2021 state outlooks, please follow the links below:
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