الكاتب: Multiple References

At the peak incidence of respiratory disease in a group of 115 housed beef calves, strategic injection of 25 calves with tilmicosin did not significantly reduce the incidence of respiratory disease in the following 30 days compared with 29 untreated control cattle (32 vs 24%, respectively). These results challenge whether strategic tilmicosin injection of normal cattle can be recommended in the control of respiratory disease in housed beef calves. Respiratory disease is common in young beef calves following housing, changes in weather conditions and other stressful events. The control of undifferentiated respiratory disease can be attempted by vaccinating calves against the common respiratory disease virus infections, including infectious bovine rhinotracheitis (IBR), para-influenza 3 (PI~) and bovine respiratory syncitial virus (BRSV) (Thomson et al., 1986) but such a programme is expensive and difficult to complete before housing of autumn-born calves. More often cattle which display dyspnoea, tachypnoea or frequent coughing indicating respiratory disease, are treated with antibiotics to control bacterial infection of the respiratory tract. The success of such a control programme relies upon high standards of stockmanship with early recognition of every case of respiratory disease. In an attempt to simplify the control of secondary bacterial infection, strategic injection of all cattle with a long-acting formulation of oxytetracycline has been recommended when more than one-third of animals in the group show clinical signs of respiratory disease (Andrews, 1983). This regimen was considered beneficial during an outbreak of respiratory disease (Laven & Andrews, 1991), but no calves were left as untreated controls. The present study investigated the efficacy of strategically-timed, single-dose tilmicosin injection on the subsequent incidence of respiratory disease in a single group of 115 housed beef calves.