[The serological investigation of milk samples for determination of cows' brucellosis and enzootic bovine leukosis]

animal diseases bovine leukosis brucellose brucellosis brucelosis cow milk cows dairy cows enfermedades de los animales enfermedades infecciosas infectious diseases lait de vache latvia leche de vaca letonia lettonie leucose bovine leucosis bovina maladie des animaux maladie infectieuse muestreo normas norme recherche research sampling standards vaca vacas lecheras vache