RESUMO
The serum immunoglobulin levels were studied in 215 calves born on 4 farms. Each farm had at least 60 cows. There was a great variation in the immunoglobulin levels at 48 hours. In those cases where the quantity and Ig concentration of colostrum was measured it was found that the serum Ig level was correlated with the total amount of Ig ingested. Where only the serum level was measured it was found that suckled calves had higher levels than bucket-fed calves. Immunoglobulin levels were not correlated with the incidence of diarrhoea or pneumonia nor with the viability of calves although calves with less than 8 mg/ml IgG1 showed a slightly higher incidence of diarrhoea. The globulin concentrations in colostrum were not influenced by the breed, the season, the number of calvings, the length of the dry period and the level of feeding during this period but the time of the first feeding or milking proved to be of prime importance.
