BOVINE SERUM TRANSFERRIN CONCENTRATION DURING ACUTE INFECTION WITH HAEMOPHILUS-SOMNUS

A novel, competitive immunoassay based on time-resolved fluorimetry wa s developed, and used to measure the serum concentration of bovine tra nsferrin during acute Haemophilus somnus pneumonia. Upper and lower li mits of normality were established using serum from healthy cattle (3. 72-1.37 mg mL(-1)). Following experimental infection with Haemophilus somnus, transferrin concentration was depressed in all calves but reco vered to pre-infection levels in groups of calves which had either no lesions, or mild lesions at necropsy between 5 and 6 days after infect ion. In a third group, which developed extensive lesions, the transfer rin concentration remained depressed. Transferrin levels remained with in the normal range for all calves during the experimental period. Tho se calves which had low transferrin concentrations pre-infection, deve loped extensive lung lesions following experimental infection with Hae mophilus somnus.