By Dwayne Summach, M.Sc., PAg., Regional Livestock Specialist, Kindersley
Efficient livestock production requires taking steps to minimize the demands generated by parasitic entities – round worms, liver flukes, tape worms, sucking lice, biting lice and flies. The use of macrocyclic lactone pour on products has been very effective at controlling parasites. However, the repeated use of products has resulted in the effectiveness being reduced.
In 2007 and 2008, Donald Bliss and his associates quantified the reduction in efficacy by collecting 4,765 fecal samples from 58 vet clinics across 19 states. The results of the study are reported in the proceedings for the forty first meeting of the American Association of Bovine Practitioners. Injectable products had an average efficacy of 72.5 per cent with a range of 42.6 per cent to 98.1 per cent. Efficacy of pour on products averaged 66.1per cent with a range of 59.7 per cent to 78.9 per cent.
One possible strategy to overcome the reduction in efficacy is to use a combination of products. When one combines the macrocyclic lactones with a benzimidazoles product, efficacy of the combination exceeds 99.9 per cent.
Another strategy to overcome parasite resistance to the pour on products is to use the benzimidazoles at different times to strategically reduce the internal parasite load. Consultation with your veterinarian will help you decide which parasite control strategy is optimal for your operation. The only way to know if your parasite control strategy is working or requires adjustment is to have your veterinarian conduct a fecal egg count reduction test.
For advice regarding parasite control on your operation, contact your veterinarian. To receive a link to the presentation titled “New Strategies for Internal Parasite Control in Cattle” made by Dr. Bliss to the 2016 Ranchers Forum, contact a Saskatchewan Ministry of Agriculture Regional Livestock Specialist, or call the Agriculture Knowledge Centre at 1-866-457-2377.