Of 31 uniquely abundant proteins in HF cattle, 24 proteins showed increased abundance after exposure to BFs, for example, complement factor proteins (C2 [Q0V7N2], C4 [P01030] and C9 [A0A3Q1MU98]), coagulation factor V (F1N0I3; F5) and mannose-binding lectin protein (O02659; MBL). Here, C4A is linked to hydrops fetalis.