There was no age difference between the groups (mean AE 1S.D.; 17.6 AE 7.4 h, range = 6-28 h, and 12.6 AE 8.1 h, range = 5-24 h, respectively; p = 0.24), and all calves had adequate plasma protein concentrations (inoculated calves, 73.3 AE 7.1, range = 64-85 g/L; controls, 63.5 AE 3.7, range = 60-70 g/L; p = 0.07) (Rea et al., 1996) .