Prozone of the complement fixation test (CFT) in the diagnosis of bovine brucellosis

Sera of cows with brucellosis and those originating from heifers vaccinated with S19 strain, were investigated. A great negative relationship was observed between the frequency of CFT prozone occurrence and the living conditions of the animals; the individual properties of the animals were less significant, and the experimental error still lesser. No relationship was found between the kind of animal stimulation (field infection or S19 vaccination), the stadium and severity of the disease, the CFT titre level, and the animal age. The herd prozone frequency showed a normal distribution in the coordinate system.