Variation in the Respiratory Virus Status of Large Bovine Units in Belgium

Abstract

Cattle in six large bovine units in Belgium were studied for five years. Blood and colostrum samples from cows near parturition, as well as blood samples from the calves before colostrum feeding and at different ages, were checked for the commonest viruses. Paired sera were also examined when respiratory infections occurred.

Results of this study were as follows:

• 1. Clinically and economically, the incidence of viral respiratory disease was important only in the beef units. Dairy units suffered only mild outbreaks of pneumo-enteritis caused by adenovirus.

• 2. Of the autumn respiratory infections, by far the most important identified viruses were RSV, reo. 1 and 2, PI3 and IBR.

• 3. Before feeding colostrum no calf had antibodies against adeno, reo. 1 and 2, IBR or RSV viruses but 10% of these calves had antibodies against BVD virus.

• 4. Antibody titres in colostrum were not related to the circulating antibodies of the cows, except for PI3. There was also no relationship between the antibody titres in colostrum and in the blood of calves two days old.

• 5. Variations, in the serum antibodies, with age were considerable but apparently unrelated to the clinical history on the farms.