The objective of this experiment was to investigate the therapeutic efficacy of feeding a supplemental bovine serum protein blend to calves challenged with virulent coronavirus. Twelve Holstein bull calves were orally challenged with 1 x 107 PFU of virulent coronavirus isolate. Infection was allowed to progress for a period of 24 h prior to the initiation of treatment. On d 1, treated calves began receiving 160 g of a blood serum protein blend (16 g IgG) mixed into milk replacer powder (67 g) at both the AM and PM feedings. Control calves received only milk replacer powder (227) at both feedings. Response to coronavirus challenge and dietary treatment was monitored prior to AM and PM feeding by the collection of multiple clinical measures. Fecal consistency was decreased (P<0.01) by coronavirus challenge, but was not affected by dietary treatment. Mean daily rectal temperature and heart rate were not affected by dietary treatment. Average packed cell volume was higher (P<0.01) in rreated calves compared to control (35.0 and 27.0 %). Coronavirus challenge resulted in an immediate increase in respiration rate, decreasing by d 7. Control calves tended to have a greater (P=0.06) average respiration rate compared to treated (28.7 vs. 26.8 breaths / min.). Treated calves had a higher (P=0.02) average feed intake versus control (0.57 vs. 0.44 kg/d). These data suggest that bovine serum supplemented milk replacer may decrease the severity of disease in young calves exposed to coronavirus. The ability of a dietary treatment to potentially alleviate symptoms of a viral enteric disease is of great importance to the dairy industry.