One of the issues with internal parasites is: Producers may not notice problems until sickness and profit losses have taken effect. In many cases, internal parasite issues have been persisting for months and potentially years.
No herd or cow is free of internal parasites, particularly in the Southeast. Working with your local veterinarian to develop a health protocol is the first part of a two-step approach for internal parasite management. The second step is pasture and nutrition management. Pasture management not only improves grass production but also improves animal health and welfare through both improved nutrition and by helping reduce parasite loads.
Cattle pick up parasites through grazing, particularly grass shorter than 4 inches. Overgrazed pastures and farms with only one main pasture without cross-fencing are very prone to internal parasite burdens. In these settings, the parasite’s life cycle is never broken and can rapidly proliferate. Internal parasites multiply by laying eggs that pass through the gut and into manure piles on the ground. The larvae find grass blades to climb on and then wait for their host for another generation to begin.
Many producers know parasites are an issue, and many apply a dewormer product as a solution. Problems arise when the same pour-on dewormer is given year after year, particularly generic brands. When these products are given, not all internal parasites are killed. The survivors lay eggs and produce another generation of resistant parasites. Eventually, these products are not effective, and parasite loads boom. These situations cause cattle to experience weight loss, sickness and poor reproduction.
Work with your veterinarian to do fecal egg counts to better understand herd parasite loads. Current research suggests a combination of both a white paste oral dewormer and an injectable product deliver best results. Using a two-step management approach will help reduce chronic issues and profit losses.
Another additional approach would be to use breeds that have good parasite resilience or target-treat cows based on need. Work with your veterinarian to find ways to target-treat and avoid parasite resistance problems. New dewormer products are not expected to be developed anytime soon. Judicious use is critical for your herd and the industry. 
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Jason Duggin
- Beef Extension Specialist
- University of Georgia
- Email Jason Duggin
