Relationship between serum immunoglobulin values and incidence of respiratory disease in calves.

Severe respiratory disease, with high morbidity and high mortality, occurred in 2 groups of bull calves (14 to 64 days old) raised in th same facility. Necropsy findings included lesions of acute or chronic bronchopneumonia. Serum immunoglobulin G (IgG) values were determined for all calves at 3 to 6 days of age. Calves that died of respiratory disease had an average IgG value of 1,267 mg/100 ml, whereas calves that lived had an average IgG value of 2,698 mg/100 ml. Calves with low serum IgG values had higher morbidity, had to be treated earlier in life, and had to be treated more frequently per day, when compared with calves that had high serum IgG values.