As we get ready to go to grass, many of us are starting to think about worming our cattle. For those of us in the south waiting for summer time temperatures to return to reduce the viability of worms, those of us in the northern areas, the warmer temperatures is the right environment for these troublesome parasites.
When we deworm it all comes down to timing. Improper timing lowers the efficacy of our treatments as well as increases the likelihood that a resistant population can form. Therefore, the best time to deworm is going to depend on your region. Again those to the south on intensively managed pastures should look at deworming in the fall and spring when temps are cool and moist. Those to the north should look at deworming in the spring at turn out or depending on calving season at that time. Another approach would be to select a drug to target dormant worms and hit them before they have a chance to mature and shed more eggs.
Time of deworming also varies with operation type. Stockers are one of the more complex systems, since you must consider multiple types of worms. Looking at which animals to deworm we must not forget our bulls, then first calf heifers. These animals are being physiologically stressed thus more susceptible to worms. The next class that would be most affected are our stockers. Finally our cow herd with calves at side would be the next group.
In reality though when dealing with worms, it’s all about numbers. Any attempt to control worm populations is beneficial. It is important to consult with your veterinarian to select the right drugs and develop a plan that works best for your operation.