We evaluated the effects of storage temperature (-20 or -80°C) and handling procedure on plasma concentrations of bovine haptoglobin and ceruloplasmin. Within each temperature, whole blood samples were: centrifuged within 2 h of collection and plasma kept frozen until analysis (control); refrigerated at 4°C for 24 h before plasma harvest and freezing (24H); or plasma harvested and frozen within 2 h after collection, but then plasma samples were thawed and refrozen 1 wk (1X), 1 and 2 wk (2X), or 1, 2 and 3 wk (3X) before analyses. Haptoglobin concentrations were greatest at 24H, but similar among remaining treatments. Ceruloplasmin concentrations were not affected by the handling procedures. Storage temperature did not affect haptoglobin concentrations, but ceruloplasmin concentrations decreased when stored at -20 versus -80°C. Except for greater concentrations after 24 h storage at 4°C, haptoglobin concentrations remained stable at either freezing temperature and through freeze-thaw cycles. Ceruloplasmin concentrations decreased after 3 freeze-thaw cycles and required lower freezing temperatures to remain stable.
Keywords: Acute-phase proteins; beef cattle; ceruloplasmin; haptoglobin; stability.