Flow diagram on the dynamical transmission of brucellosis among dairy cattle.

<p>Solid arrows represent transfer orientation of population (the department from one subclass and incoming to another subclass). For a subclass, the incoming solid arrows (point to the subclass) represent the recruitment of cattle to this subclass, and the outgoing solid arrows (point to other subclass) represent the runoff of cattle or brucella from this subclass. Dash arrows only represent incoming of brucella to environment discharged by and .