breed: a special variety of domesticated animals within a species
variety: (biology) a taxonomic category consisting of members of a species that differ from others of the same species in minor but heritable characteristics
acquired immunity: immunity to a particular disease that is not innate but has been acquired during life; immunity can be acquired by the development of antibodies after an attack of an infectious disease or by a pregnant mother passing antibodies through the placenta to a fetus or by vaccination