Production and Persistence of Antibodies in Chickens to Sheep Erythrocytes. 1. Directional Selection

Two bidirectional selection experiments were conducted to measure antibody response to sheep red blood cells. Selection in one pair of lines was for high and low 5-day antibody titers to antigen(s), and in another pair of lines for persistence and nonpersistence of antibody titers between 5 and 21 days after the antigen(s) was given. Response to selection demonstrated additive genetic variation for high and low antibody titers at 5 days and for the persistence of titers. There was no response to selection for nonpersistence of titers. Crosses of the selected populations indicated a heterotic effect for both selected traits and reciprocal effects for the persistence/nonpersistence of the antibody titers.