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Controlling nematodes in calves
J. O'Shaughnessy, B. Earley, J. F. Mee, M. L. Doherty and others
INFECTIONS with nematodes including Ostertagia ostertagi and Dictyocaulus viviparous (lungworm) can impair the health and performance of dairy calves. This study, conducted in Ireland, evaluated the efficacy of targeted selective treatment (TST) – when individual nematode-infected animals are treated rather than the whole herd – on nematode control in dairy calves.
Ninety-six calves were randomised to two groups of 48. All calves in the control group were treated with ivermectin on days 0, 42 and 84. In the TST group, individual calves were treated with subcutaneous ivermectin if they tested positive for lungworm larvae.
Twenty calves were removed from the study due to ill health: 13 in the TST group and seven in the control group. Eight of the TST group calves that were excluded had shown signs of dictyocaulosis after day 50 of the study, and lungworm larvae were detected on faecal examination in these animals. The 35 calves in the TST group that completed the study period were given a total of 52 treatments. This was around half the number of treatments given to the controls. Calf performance was similar between the two groups, with an average daily weight gain of 0.5 kg per day in the control group and 0.47 kg per day in …