Parasite treatment timing is important to effective control
Producers should determine parasite infestation levels in their herd before deciding when to deworm.
It’s common practice to treat for warbles and lice in fall, when cows come in from summer pasture, although action in both fall and spring can bring more effective results.
“Spring treatment and fall treatment will probably give better control,” said John Gilleard, a parasitology professor in the University of Calgary’s veterinary medicine department.
“(But) people should be looking at their own individual situation rather than just taking a blanket piece of advice. My advice at the moment is to try and move towards a more evidence based approach. In reality, many producers will be treating when they don’t need to treat. Other producers will be treating in a way that’s not giving them full efficacy and production gains.”
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Gilleard advises producers to treat animals and then test fecal samples in spring. The results can guide their decisions on treatment and timing.
Shelley Andrews, co-owner of Hillbilly Cattle Co. near Asquith, Sask., said she deworms with a pour-on product in fall and again in spring before the cattle are turned out.
“You can fill the whole alley up and do the cows, where if you use injectable, you’ve got to kind of catch them one at a time,” she said.
“Anything with low stress on the cattle is better for us.”
Gilleard agreed that pour-on is the easiest, but it’s not as effective as oral or injectable treatments.
There are two main types of products in Canada: benzimidazole (Safeguard) and macrocyclic lactone or avermectin (Ivomec, Dectomax and others). Safeguard, an oral product that can be given as a paste or in crumble form, kills internal parasites. Ivermectin kills both external and internal parasites.
