Etiology and predisposing factors in respiratory disease of milk-fattened veal calves

Abstract By far the most important economic losses in rearing milk-fattened calves result from respiratory disease. A brief description is given of the epidemiology of infectious diseases and of the management methods used on Swiss farms producing milk-fattened veal calves. The paper summarises the results of several surveys and experiments carried out to clarify the etiology and predisposing factors of respiratory diseases. Pure and (more frequently) mixed infections with BVD-virus, PI-3-virus, Adenoviruses, T-mycoplasmas, P. multocida and P. haemolytica can be shown to be present. Fatal cases of pneumonias are frequently associated with the presence of pasteurella. The effect of factors predisposing to the development of clinical disease has been studied: calves weighing less than 40 kg when purchased (14–28 days old) as well as weak and apparently sick animals are disease-prone and will perform poorly. Presenting the calves at a livestock market and shipping them under bad conditions impose additional stresses at the time of buying. The stable should be kept at a constant temperature and constant relative humidity, the normal values of which are given. These values seem to be of great importance for maintenance of resistance against respiratory infections. Milk-fattened calves are very susceptible to draught. Fattening with only milk substitutes and milk causes anaemia and leukopenia, which reduce the general resistance of the calves. The effects of all these factors are significantly increased by bad management, especially if there is insufficient attention to the animals and poor hygiene.