We are now well into the time of year when the level of worm eggs on the pasture has begun to rise, creating a potential disease risk for grazing animals. However, while all such animals are likely to be exposed to the same worm larvae and eggs throughout the season, control strategies for different ages of cattle differ substantially. Pharmaceutical companies and merchants can often be quick to push their products to farmers; always be sure that what you’re being sold is the right product for your animals, and that treatment is actually necessary at all! Here are the facts about two of the most important worms- Ostertagia (Brownworm) and Dictylocaulus (Lungworm).
Ostertagia Ostertagii is a roundworm which lives in the abomasum (4th stomach) of cattle. It’s almost identical to the equivalent parasite in sheep, and was for some time thought to be the very same species. Heavy infestation with the worm leads to destruction of the glands in the stomach wall, impaired digestive capability and leakage of protein from the blood into the digestive tract. The resulting symptoms are pronounced weight loss and diarrhoea, most commonly seen in first season grazing cattle aged 7 – 15 months. With a well managed first grazing season, cattle will develop a good natural immunity to this parasite, meaning that in subsequent seasons it is unlikely to be production limiting and treatment for it should be unnecessary. Immunity is strengthened after further exposure to the parasite in the second season.
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