Abstract
In 28 calves experimentall yinfected with Dictyocaulus viviparus alone, first-stage larvae disappeared from feces 83.2 ± 33.3 days after infection. In 9 calves, they did not disappear from feces within 100 days after infection. They disappeared on the 186th day at the latest.
In an experiment one calf moderately infected with D. viviparus was grazed together with 4 susceptible calves. In another experiment one mildly infected calf and 4 susceptible calves were grazed together. In the former and latter experiments, 3 and 2 calves, respectively, became infected during the grazing period. There was no difference in the severity of infection among the calves between the two experiments. The infected calves showed lower body weight gain than the uninfected.
