'Spring Cleaning': De-Worming

I think most Virginia Dairy producers are welcoming the signs of spring-warmer days, thawed water troughs and green grass-but the first tender sprigs of grass that our animals are picking at may harbor parasite larvae that have the potential to decrease the growth and health of our cattle.

This spring's milk prices can be a distraction to management activities such as de-worming. Young stock are particularly susceptible to parasites, and most of our dairy young stock are kept in pastures at high stocking rates that are not intensively rotationally grazed.

Strategic de-worming not only reduces the parasite load in the animal but can also reduce the parasite load of the pasture. Proper timing of de-worming can maximize the efficacy of your product meaning more "bang for you buck." For example de-worming heifers in mid spring reduces the parasite load that they have begun to accumulate during the early warm, moist days of spring.

Depending on your individual situation a second de-worming 3-7 weeks later may be warranted to take care of adult parasites that have matured since the initial de-worming Generally by early Summer (June-July) the hot dry weather and hopefully a good de-worming program has reduced pasture parasite loads to a low level. An additional de-worming in the fall may be beneficial for external parasite control and to reduce internal parasites before winter-feeding.

 Research regarding de-worming the lactating herd is still unclear. The system in which you house and feed your lactating cows will be a determinant to your individual operation's risk and if you should consider de-worming.

For example, Table 1, compares different cow housing scenarios and parasite loads. As always you should consult with your herd veterinarian about your de-worming program and the products that you wish to use.